Copyright (c) 1998 Association of Mizar Users
environ vocabulary BOOLE, ARYTM_1, FINSEQ_1, MATRIX_1, MATRIX_2, PRE_TOPC, EUCLID, ARYTM_3, TOPREAL1, METRIC_1, RELAT_2, JORDAN1, CONNSP_1, PCOMPS_1, SPPOL_1, MCART_1, GOBOARD1, TREES_1, PSCOMP_1, SPRECT_1, COMPTS_1, JORDAN3, RELAT_1, SPPOL_2, FUNCT_1, TARSKI, RFINSEQ, GROUP_2, SEQM_3, GOBOARD5, GOBOARD9, SUBSET_1, TOPREAL4, JORDAN5D, GOBOARD2, SPRECT_2, ABSVALUE, CARD_1, ORDINAL2, TOPS_1, JORDAN5C, FINSEQ_5, FINSEQ_4, ARYTM; notation TARSKI, XBOOLE_0, ENUMSET1, ZFMISC_1, SUBSET_1, ORDINAL1, XREAL_0, REAL_1, NAT_1, ABSVALUE, BINARITH, CARD_1, RFINSEQ, FUNCT_1, FINSEQ_1, FINSEQ_4, FINSEQ_5, MATRIX_1, MATRIX_2, STRUCT_0, METRIC_1, PRE_TOPC, TOPS_1, COMPTS_1, CONNSP_1, PCOMPS_1, EUCLID, TOPREAL1, TOPREAL4, JORDAN1, PSCOMP_1, GOBOARD1, GOBOARD2, SPPOL_1, SPPOL_2, GOBOARD5, GOBOARD9, JORDAN3, JORDAN5C, JORDAN5D, SPRECT_1, SPRECT_2; constructors SPRECT_2, PSCOMP_1, REALSET1, SPRECT_1, SPPOL_1, COMPTS_1, REAL_1, GOBOARD2, BINARITH, JORDAN3, TOPREAL2, TOPREAL4, GOBOARD9, CONNSP_1, TOPS_1, JORDAN1, JORDAN5C, TOPS_2, MATRIX_2, ENUMSET1, JORDAN5D, ABSVALUE, RFINSEQ, FINSEQ_4, TOPMETR, MEMBERED; clusters STRUCT_0, RELSET_1, SPRECT_1, SPRECT_2, EUCLID, SPPOL_2, GOBOARD2, XREAL_0, FINSEQ_5, ARYTM_3, MEMBERED, ZFMISC_1; requirements REAL, NUMERALS, BOOLE, SUBSET, ARITHM; definitions TARSKI, SPRECT_2, JORDAN1, TOPREAL4, GOBOARD1, XBOOLE_0; theorems FINSEQ_4, TARSKI, FINSEQ_3, FINSEQ_1, SPRECT_2, GOBOARD7, PSCOMP_1, SPRECT_1, TOPREAL3, AXIOMS, REAL_1, REAL_2, SPPOL_2, NAT_1, SPPOL_1, EUCLID, ZFMISC_1, TOPREAL1, GOBOARD5, JORDAN5D, FINSEQ_5, AMI_5, FINSEQ_6, JORDAN4, JORDAN3, TOPREAL5, TOPS_1, GOBRD11, GOBOARD9, TOPMETR, GOBOARD6, JORDAN1, CONNSP_1, SUBSET_1, GOBRD12, JORDAN5C, JORDAN6, CQC_THE1, MATRIX_2, SCMFSA_7, GOBOARD1, ENUMSET1, CARD_2, GOBOARD2, SQUARE_1, BINARITH, NAT_2, ABSVALUE, GOBOARD8, RLVECT_1, PARTFUN2, FUNCT_1, XBOOLE_0, XBOOLE_1, XREAL_0, XCMPLX_1, FINSEQ_2; schemes DOMAIN_1; begin :: Preliminaries reserve i,j,k,n,m for Nat; canceled; theorem for A,B,C,p being set st A c= B & B /\ C = {p} & p in A holds A /\ C = {p} proof let A,B,C,p be set such that A1: A c= B; assume A2: B /\ C = {p}; then p in B /\ C by TARSKI:def 1; then A3: p in C by XBOOLE_0:def 3; assume p in A; then A4: p in A /\ C by A3,XBOOLE_0:def 3; A /\ C c= { p } by A1,A2,XBOOLE_1:26; hence A /\ C = {p} by A4,ZFMISC_1:39; end; theorem Th3: for q,r,s,t being Real st t >= 0 & t <= 1 & s = (1-t)*q + t*r & q <= s & r < s holds t = 0 proof let q,r,s,t be Real such that A1: t >= 0 and A2: t <= 1 and A3: s = (1-t)*q + t*r and A4: q <= s and A5: r < s; A6: 1*s = ((1-t) + t)*s by XCMPLX_1:27 .= (1-t)*s + t*s by XCMPLX_1:8; assume t <> 0; then A7: t*r < t*s by A1,A5,REAL_1:70; 1-t >= 0 by A2,SQUARE_1:12; then (1-t)*q <= (1-t)*s by A4,AXIOMS:25; hence contradiction by A3,A6,A7,REAL_1:67; end; theorem Th4: for q,r,s,t being Real st t >= 0 & t <= 1 & s = (1-t)*q + t*r & q >= s & r > s holds t = 0 proof let q,r,s,t be Real such that A1: t >= 0 and A2: t <= 1 and A3: s = (1-t)*q + t*r and A4: q >= s and A5: r > s; A6: 1*s = ((1-t) + t)*s by XCMPLX_1:27 .= (1-t)*s + t*s by XCMPLX_1:8; assume t <> 0; then A7: t*r > t*s by A1,A5,REAL_1:70; 1-t >= 0 by A2,SQUARE_1:12; then (1-t)*q >= (1-t)*s by A4,AXIOMS:25; hence contradiction by A3,A6,A7,REAL_1:67; end; theorem Th5: i-'k <= j implies i <= j + k proof assume A1: i-'k <= j; per cases; suppose A2: i >= k; i-'k +k <= j + k by A1,AXIOMS:24; hence i <= j + k by A2,AMI_5:4; suppose A3: i <= k; k <= j + k by NAT_1:29; hence i <= j + k by A3,AXIOMS:22; end; theorem Th6: i <= j + k implies i-'k <= j proof assume i <= j + k; then i -' k <= j + k -' k by JORDAN3:5; hence i-'k <= j by BINARITH:39; end; theorem Th7: i <= j -' k & k <= j implies i + k <= j proof assume that A1: i <= j -' k and A2: j >= k; i + k <= j -' k + k by A1,AXIOMS:24; hence i + k <= j by A2,AMI_5:4; end; theorem j + k <= i implies k <= i -' j proof assume A1: j + k <= i; per cases by A1,AXIOMS:21; suppose j + k = i; hence k <= i -' j by BINARITH:39; suppose j + k < i; hence k <= i -' j by Th5; end; theorem k <= i & i < j implies i -' k < j -' k proof assume that A1: k <= i and A2: i < j; A3: k <= j by A1,A2,AXIOMS:22; i -' k + k = i by A1,AMI_5:4; then i -' k + k < j -' k + k by A2,A3,AMI_5:4; hence i -' k < j -' k by AXIOMS:24; end; theorem i < j & k < j implies i -' k < j -' k proof assume that A1: i < j and A2: k < j; per cases; suppose k <= i; then A3: i -' k = i - k by SCMFSA_7:3; j -' k = j - k by A2,SCMFSA_7:3; hence thesis by A1,A3,REAL_1:54; suppose k > i; then i - k < 0 by REAL_2:105; then A4: i -' k = 0 by BINARITH:def 3; j -' k <> 0 by A2,JORDAN4:1; hence thesis by A4,NAT_1:19; end; theorem for D being non empty set for f being non empty FinSequence of D, g being FinSequence of D holds (g^f)/.len(g^f) = f/.len f proof let D be non empty set, f be non empty FinSequence of D, g be FinSequence of D; A1: len(g^f) = len g + len f by FINSEQ_1:35; len f <> 0 by FINSEQ_1:25; then len f >= 1 by RLVECT_1:99; hence thesis by A1,GOBOARD2:5; end; theorem Th12: for a,b,c,d being set holds Indices (a,b)][(c,d) = {[1,1],[1,2],[2,1],[2,2]} proof let a,b,c,d be set; thus Indices (a,b)][(c,d) = [:Seg 2,Seg 2:] by MATRIX_2:3 .= [:{1},Seg 2:] \/ [:{2},Seg 2:] by FINSEQ_1:4,ZFMISC_1:132 .= [:{1},Seg 2:] \/ {[2,1], [2,2]} by FINSEQ_1:4,ZFMISC_1:36 .= { [1,1], [1,2]} \/ {[2,1], [2,2]} by FINSEQ_1:4,ZFMISC_1:36 .= {[1,1],[1,2],[2,1],[2,2]} by ENUMSET1:45; end; begin :: Euclidean Space theorem Th13: for p,q being Point of TOP-REAL n, r being Real st 0 < r & p = (1-r)*p+r*q holds p = q proof let p,q be Point of TOP-REAL n, r be Real such that A1: 0 < r and A2: p = (1-r)*p+r*q; A3: (1-r)*p+r*p = ((1-r)+r)*p by EUCLID:37 .= 1*p by XCMPLX_1:27 .= p by EUCLID:33; r*p = r*p + 0.REAL n by EUCLID:31 .= r*p + ((1-r)*p + -(1-r)*p) by EUCLID:40 .= r*q + (1-r)*p + -(1-r)*p by A2,A3,EUCLID:30 .= r*q + ((1-r)*p + -(1-r)*p) by EUCLID:30 .= r*q + 0.REAL n by EUCLID:40 .= r*q by EUCLID:31; hence p = q by A1,EUCLID:38; end; theorem Th14: for p,q being Point of TOP-REAL n, r being Real st r < 1 & p = (1-r)*q+r*p holds p = q proof let p,q be Point of TOP-REAL n, r be Real such that A1: r < 1 and A2: p = (1-r)*q+r*p; set s = 1 -r; r + 0 < 1 by A1; then A3: 0 < 1 - r by REAL_1:86; p = (1-s)*p+s*q by A2,XCMPLX_1:18; hence p = q by A3,Th13; end; theorem for p,q being Point of TOP-REAL n st p = 1/2*(p+q) holds p = q proof let p,q be Point of TOP-REAL n; assume p = 1/2*(p+q); then p = (1 - 1/2)*p + 1/2*q by EUCLID:36; hence p = q by Th13; end; theorem Th16: for p,q,r being Point of TOP-REAL n st q in LSeg(p,r) & r in LSeg(p,q) holds q = r proof let p,q,r be Point of TOP-REAL n; assume q in LSeg(p,r); then consider r1 being Real such that A1: 0<=r1 and A2: r1<=1 and A3: q = (1-r1)*p+r1*r by SPPOL_1:21; assume r in LSeg(p,q); then consider r2 being Real such that A4: 0<=r2 and A5: r2<=1 and A6: r = (1-r2)*p+r2*q by SPPOL_1:21; A7: (1-r1)+r1*(1-r2) = (1-r1)+(r1*1-r1*r2) by XCMPLX_1:40 .= (1-r1)+r1-r1*r2 by XCMPLX_1:29 .= 1 - r1*r2 by XCMPLX_1:27; A8: (1-r2)+r2*(1-r1) = (1-r2)+(r2*1-r2*r1) by XCMPLX_1:40 .= (1-r2)+r2-r2*r1 by XCMPLX_1:29 .= 1 - r2*r1 by XCMPLX_1:27; A9: q = (1-r1)*p+(r1*((1-r2)*p)+r1*(r2*q)) by A3,A6,EUCLID:36 .= (1-r1)*p+r1*((1-r2)*p)+r1*(r2*q) by EUCLID:30 .= (1-r1)*p+r1*(1-r2)*p+r1*(r2*q) by EUCLID:34 .= (1 - r1*r2)*p+r1*(r2*q) by A7,EUCLID:37 .= (1 - r1*r2)*p+r1*r2*q by EUCLID:34; A10: r = (1-r2)*p+(r2*((1-r1)*p)+r2*(r1*r)) by A3,A6,EUCLID:36 .= (1-r2)*p+r2*((1-r1)*p)+r2*(r1*r) by EUCLID:30 .= (1-r2)*p+r2*(1-r1)*p+r2*(r1*r) by EUCLID:34 .= (1 - r2*r1)*p+r2*(r1*r) by A8,EUCLID:37 .= (1 - r2*r1)*p+r2*r1*r by EUCLID:34; A11: r1*r2 <= 1 by A1,A2,A4,A5,REAL_2:140; per cases by A11,REAL_1:def 5; suppose A12: r1*r2 = 1; then 1 <= r1 or 1 <= r2 by A1,A4,REAL_2:139; then 1*r1 = 1 or 1*r2 = 1 by A2,A5,AXIOMS:21; hence q = 0 * p+r by A3,A12,EUCLID:33 .= 0.REAL n+r by EUCLID:33 .= r by EUCLID:31; suppose A13: r1*r2 < 1; hence q = p by A9,Th14 .= r by A10,A13,Th14; end; begin :: Euclidean Plane theorem Th17: for A being non empty Subset of TOP-REAL 2, p being Element of Euclid 2, r being Real st A = Ball(p,r) holds A is connected proof let A be non empty Subset of TOP-REAL 2, p be Element of Euclid 2, r be Real such that A1: A = Ball(p,r); A is convex proof let w1,w2 be Point of TOP-REAL 2; assume w1 in A & w2 in A; hence LSeg(w1,w2) c= A by A1,TOPREAL3:28; end; hence A is connected by JORDAN1:9; end; theorem Th18: for A, B being Subset of TOP-REAL 2 st A is open & B is_a_component_of A holds B is open proof let A, B be Subset of TOP-REAL 2 such that A1: A is open and A2: B is_a_component_of A; A3: B c= A by A2,SPRECT_1:7; A4: TOP-REAL 2 = TopSpaceMetr (Euclid 2) by EUCLID:def 8; reconsider C = B, D = A as Subset of TopSpaceMetr Euclid 2 by EUCLID:def 8; for p being Point of Euclid 2 st p in C ex r being real number st r>0 & Ball(p,r) c= C proof let p be Point of Euclid 2; assume A5: p in C; then consider r being real number such that A6: r > 0 and A7: Ball(p,r) c= D by A1,A3,A4,TOPMETR:22; reconsider r as Real by XREAL_0:def 1; take r; thus r>0 by A6; the carrier of TopSpaceMetr Euclid 2 = the carrier of Euclid 2 by TOPMETR:16; then reconsider E = Ball(p,r) as Subset of TOP-REAL 2 by A4; A8: p in E by A6,GOBOARD6:4; then A9: B meets E by A5,XBOOLE_0:3; E is connected by A8,Th17; hence Ball(p,r) c= C by A2,A7,A9,GOBOARD9:6; end; hence B is open by A4,TOPMETR:22; end; theorem Th19: for p,q,r being Point of TOP-REAL 2 st LSeg(p,q) is horizontal & r in LSeg(p,q) holds p`2 = r`2 proof let p,q,r be Point of TOP-REAL 2; assume LSeg(p,q) is horizontal; then A1: p`2 = q`2 by SPPOL_1:36; assume r in LSeg(p,q); then consider t being Real such that 0 <= t & t <= 1 and A2: r = (1-t)*p+t*q by SPPOL_1:21; thus p`2 = 1*p`2 .= (1-t+t)*p`2 by XCMPLX_1:27 .= (1-t)*p`2+t*p`2 by XCMPLX_1:8 .= ((1-t)*p)`2+t*q`2 by A1,TOPREAL3:9 .= ((1-t)*p)`2+(t*q)`2 by TOPREAL3:9 .= r`2 by A2,TOPREAL3:7; end; theorem Th20: for p,q,r being Point of TOP-REAL 2 st LSeg(p,q) is vertical & r in LSeg(p,q) holds p`1 = r`1 proof let p,q,r be Point of TOP-REAL 2; assume LSeg(p,q) is vertical; then A1: p`1 = q`1 by SPPOL_1:37; assume r in LSeg(p,q); then consider t being Real such that 0 <= t & t <= 1 and A2: r = (1-t)*p+t*q by SPPOL_1:21; thus p`1 = 1*p`1 .= (1-t+t)*p`1 by XCMPLX_1:27 .= (1-t)*p`1+t*p`1 by XCMPLX_1:8 .= ((1-t)*p)`1+t*q`1 by A1,TOPREAL3:9 .= ((1-t)*p)`1+(t*q)`1 by TOPREAL3:9 .= r`1 by A2,TOPREAL3:7; end; theorem for p,q,r,s being Point of TOP-REAL 2 st LSeg(p,q) is horizontal & LSeg(r,s) is horizontal & LSeg(p,q) meets LSeg(r,s) holds p`2= r`2 proof let p,q,r,s be Point of TOP-REAL 2 such that A1: LSeg(p,q) is horizontal and A2: LSeg(r,s) is horizontal; assume LSeg(p,q) meets LSeg(r,s); then LSeg(p,q) /\ LSeg(r,s) <> {} by XBOOLE_0:def 7; then consider x being Point of TOP-REAL 2 such that A3: x in LSeg(p,q) /\ LSeg(r,s) by SUBSET_1:10; A4: x in LSeg(r,s) by A3,XBOOLE_0:def 3; x in LSeg(p,q) by A3,XBOOLE_0:def 3; hence p`2 = x`2 by A1,Th19 .= r`2 by A2,A4,Th19; end; theorem for p,q,r being Point of TOP-REAL 2 st LSeg(p,q) is vertical & LSeg(q,r) is horizontal holds LSeg(p,q) /\ LSeg(q,r) = {q} proof let p,q,r be Point of TOP-REAL 2 such that A1: LSeg(p,q) is vertical and A2: LSeg(q,r) is horizontal; for x being set holds x in LSeg(p,q) /\ LSeg(q,r) iff x = q proof let x be set; thus x in LSeg(p,q) /\ LSeg(q,r) implies x = q proof assume A3: x in LSeg(p,q) /\ LSeg(q,r); then reconsider x as Point of TOP-REAL 2; x in LSeg(p,q) & x in LSeg(q,r) by A3,XBOOLE_0:def 3; then x`1 = q`1 & x`2 = q`2 by A1,A2,Th19,Th20; hence thesis by TOPREAL3:11; end; assume x = q; then x in LSeg(p,q) & x in LSeg(q,r) by TOPREAL1:6; hence thesis by XBOOLE_0:def 3; end; hence LSeg(p,q) /\ LSeg(q,r) = {q} by TARSKI:def 1; end; theorem for p,q,r,s being Point of TOP-REAL 2 st LSeg(p,q) is horizontal & LSeg(s,r) is vertical & r in LSeg(p,q) holds LSeg(p,q) /\ LSeg(s,r) = {r} proof let p,q,r,s be Point of TOP-REAL 2 such that A1: LSeg(p,q) is horizontal and A2: LSeg(s,r) is vertical and A3: r in LSeg(p,q); for x being set holds x in LSeg(p,q) /\ LSeg(s,r) iff x = r proof let x be set; thus x in LSeg(p,q) /\ LSeg(s,r) implies x = r proof assume A4: x in LSeg(p,q) /\ LSeg(s,r); then reconsider x as Point of TOP-REAL 2; A5: p`2 = r`2 by A1,A3,Th19; x in LSeg(p,q) & x in LSeg(s,r) by A4,XBOOLE_0:def 3; then x`2 = p`2 & x`1 = r`1 by A1,A2,Th19,Th20; hence thesis by A5,TOPREAL3:11; end; assume x = r; then x in LSeg(p,q) & x in LSeg(s,r) by A3,TOPREAL1:6; hence thesis by XBOOLE_0:def 3; end; hence LSeg(p,q) /\ LSeg(s,r) = {r} by TARSKI:def 1; end; begin :: Main reserve p,q for Point of TOP-REAL 2; reserve G for Go-board; theorem 1 <= j & j <= k & k <= width G & 1 <= i & i <= len G implies G*(i,j)`2 <= G*(i,k)`2 proof assume A1: 1 <= j & j <= k & k <= width G & 1 <= i & i <= len G; per cases by A1,REAL_1:def 5; suppose j < k; hence G*(i,j)`2 <= G*(i,k)`2 by A1,GOBOARD5:5; suppose j = k; hence thesis; end; theorem 1 <= j & j <= width G & 1 <= i & i <= k & k <= len G implies G*(i,j)`1 <= G*(k,j)`1 proof assume A1: 1 <= j & j <= width G & 1 <= i & i <= k & k <= len G; per cases by A1,REAL_1:def 5; suppose i < k; hence G*(i,j)`1 <= G*(k,j)`1 by A1,GOBOARD5:4; suppose i = k; hence thesis; end; reserve C for Subset of TOP-REAL 2; theorem Th26: LSeg(NW-corner C,NE-corner C) c= L~SpStSeq C proof A1: LSeg(NW-corner C,NE-corner C) c= LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C) by XBOOLE_1:7; LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C) c= (LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C)) \/ (LSeg(SE-corner C,SW-corner C) \/ LSeg(SW-corner C,NW-corner C)) by XBOOLE_1: 7; then LSeg(NW-corner C,NE-corner C) c= (LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C)) \/ (LSeg(SE-corner C,SW-corner C) \/ LSeg(SW-corner C,NW-corner C)) by A1,XBOOLE_1:1; hence thesis by SPRECT_1:43; end; theorem Th27: N-most C c= LSeg(NW-corner C,NE-corner C) proof N-most C = LSeg(NW-corner C, NE-corner C) /\ C by PSCOMP_1:def 39; hence N-most C c= LSeg(NW-corner C,NE-corner C) by XBOOLE_1:17; end; theorem Th28: for C being non empty compact Subset of TOP-REAL 2 holds N-min C in LSeg(NW-corner C,NE-corner C) proof let C be non empty compact Subset of TOP-REAL 2; A1: N-min C in N-most C by PSCOMP_1:101; N-most C c= LSeg(NW-corner C,NE-corner C) by Th27; hence N-min C in LSeg(NW-corner C,NE-corner C) by A1; end; theorem LSeg(NW-corner C,NE-corner C) is horizontal proof (NW-corner C)`2 = N-bound C by PSCOMP_1:75 .= (NE-corner C)`2 by PSCOMP_1:77; hence LSeg(NW-corner C,NE-corner C) is horizontal by SPPOL_1:36; end; canceled; theorem :: JORDAN3:76 for g being FinSequence of TOP-REAL 2, p being Point of TOP-REAL 2 st g/.1 <> p & ((g/.1)`1 = p`1 or (g/.1)`2 = p`2) & g is_S-Seq & LSeg(p,g/.1) /\ L~g={ g/.1 } holds <*p*>^g is_S-Seq proof let g be FinSequence of TOP-REAL 2, p be Point of TOP-REAL 2 such that A1: g/.1 <> p and A2: (g/.1)`1 = p`1 or (g/.1)`2 = p`2 and A3: g is_S-Seq and A4: LSeg(p,g/.1) /\ L~g={ g/.1 }; set f = <*p,g/.1*>; reconsider g' = g as S-Sequence_in_R2 by A3; A5: 1 in dom g' by FINSEQ_5:6; A6: len f = 1+1 by FINSEQ_1:61; then A7: len f -' 1 = 1 by BINARITH:39; A8: f.len f = g/.1 by A6,FINSEQ_1:61 .= g.1 by A5,FINSEQ_4:def 4; A9: f is_S-Seq by A1,A2,SPPOL_2:46; A10: L~f /\ L~g ={ g/.1 } by A4,SPPOL_2:21 .={g.1} by A5,FINSEQ_4:def 4; mid(f,1,len f-'1) = <*f/.1*> by A6,A7,JORDAN4:27 .= <*p*> by FINSEQ_4:26; hence <*p*>^g is_S-Seq by A3,A8,A9,A10,JORDAN3:80; end; canceled; theorem for f being S-Sequence_in_R2, p being Point of TOP-REAL 2 st 1 <j & j <= len f & p in L~mid(f,1,j) holds LE p, f/.j, L~f, f/.1, f/.len f proof let f be S-Sequence_in_R2, p be Point of TOP-REAL 2 such that A1: 1 <j & j <= len f and A2: p in L~mid(f,1,j); A3: L~f is_an_arc_of f/.1,f/.len f by TOPREAL1:31; consider i such that A4: 1 <= i & i+1 <= len mid(f,1,j) and A5: p in LSeg(mid(f,1,j),i) by A2,SPPOL_2:13; A6: j -' 1 + 1 = j by A1,AMI_5:4; then A7: i+1 <= j by A1,A4,JORDAN4:20; A8: i = i + 1 -' 1 by BINARITH:39; i < j-'1+1 by A6,A7,NAT_1:38; then A9: LSeg(mid(f,1,j),i) = LSeg(f,i+1-'1) by A1,A4,JORDAN4:31; i+1 <= len f by A1,A7,AXIOMS:22; then A10: LE p, f/.(i+1), L~f, f/.1, f/.len f by A4,A5,A8,A9,JORDAN5C:26; 1 <= i+1 by NAT_1:29; then LE f/.(i+1), f/.j, L~f, f/.1, f/.len f by A1,A7,JORDAN5C:24; hence LE p, f/.j, L~f, f/.1, f/.len f by A3,A10,JORDAN5C:13; end; theorem :: JORDAN4:47 for h being FinSequence of TOP-REAL 2 st i in dom h & j in dom h holds L~mid(h,i,j) c= L~h proof let h be FinSequence of TOP-REAL 2; assume i in dom h & j in dom h; then 1 <= i & i <= len h & 1 <= j & j <= len h by FINSEQ_3:27; hence thesis by JORDAN4:47; end; theorem 1 <= i & i < j implies for f being FinSequence of TOP-REAL 2 st j <= len f holds L~mid(f,i,j) = LSeg(f,i) \/ L~mid(f,i+1,j) proof assume that A1: 1 <= i and A2: i < j; let f be FinSequence of TOP-REAL 2 such that A3: j <= len f; A4: 1 <= i+1 by NAT_1:29; A5: i+1 <= j by A2,NAT_1:38; set A = { LSeg(f,k): i <= k & k < j}, B = { LSeg(f,k): i+1 <= k & k < j}; A6: A = B \/ {LSeg(f,i)} proof thus A c= B \/ {LSeg(f,i)} proof let e be set; assume e in A; then consider k such that A7: e = LSeg(f,k) and A8: i <= k and A9: k < j; i = k or i < k by A8,AXIOMS:21; then i = k or i+1 <= k by NAT_1:38; then e in B or e in {LSeg(f,i)} by A7,A9,TARSKI:def 1; hence e in B \/ {LSeg(f,i)} by XBOOLE_0:def 2; end; let e be set; assume A10: e in B \/ {LSeg(f,i)}; per cases by A10,XBOOLE_0:def 2; suppose e in B; then consider k such that A11: e = LSeg(f,k) and A12: i+1 <= k and A13: k < j; i < k by A12,NAT_1:38; hence e in A by A11,A13; suppose e in {LSeg(f,i)}; then e = LSeg(f,i) by TARSKI:def 1; hence e in A by A2; end; thus L~mid(f,i,j) = union A by A1,A2,A3,SPRECT_2:18 .= union B \/ union{LSeg(f,i)} by A6,ZFMISC_1:96 .= union B \/ LSeg(f,i) by ZFMISC_1:31 .= LSeg(f,i) \/ L~mid(f,i+1,j) by A3,A4,A5,SPRECT_2:18; end; theorem for f being FinSequence of TOP-REAL 2 st 1 <= i holds i < j & j <= len f implies L~mid(f,i,j) = L~mid(f,i,j -' 1) \/ LSeg(f,j -' 1) proof let f be FinSequence of TOP-REAL 2 such that A1: 1 <= i and A2: i < j and A3: j <= len f; A4: i <= j -' 1 by A2,JORDAN3:12; j -' 1 <= j by GOBOARD9:2; then A5: j -' 1 <= len f by A3,AXIOMS:22; set A = { LSeg(f,k): i <= k & k < j}, B = { LSeg(f,k): i <= k & k < j -' 1}; A6: A = B \/ {LSeg(f,j -' 1)} proof thus A c= B \/ {LSeg(f,j -' 1)} proof let e be set; assume e in A; then consider k such that A7: e = LSeg(f,k) and A8: i <= k and A9: k < j; k <= j -' 1 by A9,JORDAN3:12; then j -' 1 = k or k < j -' 1 by AXIOMS:21; then e in B or e in {LSeg(f,j -' 1)} by A7,A8,TARSKI:def 1; hence e in B \/ {LSeg(f,j -' 1)} by XBOOLE_0:def 2; end; let e be set; assume A10: e in B \/ {LSeg(f,j -' 1)}; A11: j -' 1 <= j by GOBOARD9:2; per cases by A10,XBOOLE_0:def 2; suppose e in B; then consider k such that A12: e = LSeg(f,k) and A13: i <= k and A14: k < j -' 1; k < j by A11,A14,AXIOMS:22; hence e in A by A12,A13; suppose e in {LSeg(f,j -' 1)}; then A15: e = LSeg(f,j -' 1) by TARSKI:def 1; 1 <= j & 1 <= j -' 1 by A1,A2,A4,AXIOMS:22; then j-' 1 < j by JORDAN3:14; hence e in A by A4,A15; end; thus L~mid(f,i,j) = union A by A1,A2,A3,SPRECT_2:18 .= union B \/ union{LSeg(f,j -' 1)} by A6,ZFMISC_1:96 .= union B \/ LSeg(f,j -' 1) by ZFMISC_1:31 .= L~mid(f,i,j -' 1) \/ LSeg(f,j -' 1) by A1,A4,A5,SPRECT_2:18; end; canceled; theorem for f, g being FinSequence of TOP-REAL 2 st f is_S-Seq & g is_S-Seq & ((f/.len f)`1 = (g/.1)`1 or (f/.len f)`2 = (g/.1)`2) & L~f misses L~g & LSeg(f/.len f,g/.1) /\ L~f={ f/.len f } & LSeg(f/.len f,g/.1) /\ L~g={ g/.1 } holds f^g is_S-Seq proof let f,g be FinSequence of TOP-REAL 2 such that A1: f is_S-Seq and A2: g is_S-Seq and A3: (f/.len f)`1 = (g/.1)`1 or (f/.len f)`2 = (g/.1)`2 and A4: L~f misses L~g and A5: LSeg(f/.len f,g/.1) /\ L~f={ f/.len f } and A6: LSeg(f/.len f,g/.1) /\ L~g={ g/.1 }; set h = <*f/.len f*>^g; A7: len f >= 2 by A1,TOPREAL1:def 10; A8: len g >= 2 by A2,TOPREAL1:def 10; 1 <= len f by A7,AXIOMS:22; then A9: len f in dom f by FINSEQ_3:27; A10: len g >= 1 by A8,AXIOMS:22; then A11: 1 in dom g by FINSEQ_3:27; A12: len h = len<*f/.len f*>+len g by FINSEQ_1:35 .= len g + 1 by FINSEQ_1:56; then A13: len h >= 1+1 by A10,AXIOMS:24; len g <> 0 by A2,TOPREAL1:def 10; then A14: g is non empty by FINSEQ_1:25; A15: f.len f = f/.len f by A9,FINSEQ_4:def 4 .=h.1 by FINSEQ_1:58; f/.len f in L~f & g/.1 in L~g by A7,A8,A9,A11,GOBOARD1:16; then f/.len f <> g/.1 by A4,XBOOLE_0:3; then A16: h is_S-Seq by A2,A3,A6,SPRECT_2:64; A17: L~f /\ L~h = L~f /\ (LSeg(f/.len f,g/.1) \/ L~g) by A14,SPPOL_2:20 .= L~f /\ LSeg(f/.len f,g/.1) \/ L~f /\ L~g by XBOOLE_1:23 .= L~f /\ LSeg(f/.len f,g/.1) \/ {} by A4,XBOOLE_0:def 7 .={h.1} by A5,A9,A15,FINSEQ_4:def 4; mid(h,2,len h) = (h/^(1+1-'1))|(len h-'2+1) by A13,JORDAN3:def 1 .= (h/^1)|(len h-'2+1) by BINARITH:39 .= g|(len h-'2+1) by FINSEQ_6:49 .= g|(len h-'1-'1+1) by JORDAN3:8 .= g|(len g-'1+1) by A12,BINARITH:39 .= g|len g by A10,AMI_5:4 .= g by TOPREAL1:2; hence f^g is_S-Seq by A1,A15,A16,A17,JORDAN3:73; end; theorem for f being S-Sequence_in_R2, p being Point of TOP-REAL 2 st p in L~f holds (R_Cut(f,p))/.1 = f/.1 proof let f be S-Sequence_in_R2, p be Point of TOP-REAL 2; set i = Index(p,f); assume A1: p in L~f; then A2: 1 <= i & i <= len f by JORDAN3:41; A3: 1 in dom f by FINSEQ_5:6; p = f.1 or p <> f.1; then len R_Cut(f,p) = Index(p,f) or len R_Cut(f,p) = Index(p,f) + 1 by A1,JORDAN3:60; then 1 <= len R_Cut(f,p) by A1,JORDAN3:41,NAT_1:29; hence (R_Cut(f,p))/.1 = R_Cut(f,p).1 by FINSEQ_4:24 .= f.1 by A1,A2,JORDAN3:59 .= f/.1 by A3,FINSEQ_4:def 4; end; theorem for f being S-Sequence_in_R2, p,q being Point of TOP-REAL 2 st 1 <=j & j < len f & p in LSeg(f,j) & q in LSeg(f/.j,p) holds LE q, p, L~f, f/.1, f/.len f proof let f be S-Sequence_in_R2, p,q be Point of TOP-REAL 2 such that A1: 1 <=j & j < len f and A2: p in LSeg(f,j) and A3: q in LSeg(f/.j,p); A4: L~f is_an_arc_of f/.1, f/.len f by TOPREAL1:31; A5: j+1 <= len f by A1,NAT_1:38; then A6: LSeg(f,j) = LSeg(f/.j,f/.(j+1)) by A1,TOPREAL1:def 5; f/.j in LSeg(f,j) by A1,A5,TOPREAL1:27; then A7: LSeg(f/.j,p) c= LSeg(f,j) by A2,A6,TOPREAL1:12; then A8: q in LSeg(f,j) by A3; A9: LSeg(f,j) c= L~f by TOPREAL3:26; per cases; suppose p = q; hence thesis by A2,A4,A9,JORDAN5C:9; suppose A10: q <> p; for i, j being Nat st q in LSeg(f,i) & p in LSeg(f,j) & 1 <= i & i+1 <= len f & 1 <= j & j+1 <= len f holds i <= j & (i = j implies LE q,p,f/.i,f/.(i+1)) proof let i1, i2 be Nat such that A11: q in LSeg(f,i1) and A12: p in LSeg(f,i2) and A13: 1 <= i1 & i1+1 <= len f and A14: 1 <= i2 & i2+1 <= len f; A15: now assume i2 + 1 > j & j+1 > i2; then i2 <= j & j <= i2 by NAT_1:38; hence i2 = j by AXIOMS:21; end; A16: p in LSeg(f,i2) /\ LSeg(f,j) by A2,A12,XBOOLE_0:def 3; then LSeg(f,i2) meets LSeg(f,j) by XBOOLE_0:4; then i2 + 1 >= j & j + 1 >= i2 by TOPREAL1:def 9; then A17: i2 + 1 = j or i2 = j or j + 1 = i2 by A15,AXIOMS:21; A18: now assume A19: i2 + 1 = j; i2+(1+1) = i2+1+1 by XCMPLX_1:1; then i2+2 <= len f by A1,A19,NAT_1:38; then p in {f/.j} by A14,A16,A19,TOPREAL1:def 8; then p = f/.j by TARSKI:def 1; then q in {p} by A3,TOPREAL1:7; hence contradiction by A10,TARSKI:def 1; end; then A20: i2 >= j by A17,NAT_1:29; A21: now assume i1 + 1 > j & j+1 > i1; then i1 <= j & j <= i1 by NAT_1:38; hence i1 = j by AXIOMS:21; end; A22: q in LSeg(f,i1) /\ LSeg(f,j) by A3,A7,A11,XBOOLE_0:def 3; then LSeg(f,i1) meets LSeg(f,j) by XBOOLE_0:4; then A23: i1 + 1 >= j & j + 1 >= i1 by TOPREAL1:def 9; then A24: i1 + 1 = j or i1 = j or j + 1 = i1 by A21,AXIOMS:21; 1 <= j+1 by NAT_1:29; then A25: j+1 in dom f by A5,FINSEQ_3:27; A26: j in dom f by A1,FINSEQ_3:27; A27:now assume f/.(j+1)=f/.j; then j = j+1 by A25,A26,PARTFUN2:17; hence contradiction by REAL_1:69; end; A28: now assume A29: i1 = j + 1; j+(1+1) = j+1+1 by XCMPLX_1:1; then q in {f/.(j+1)} by A1,A13,A22,A29,TOPREAL1:def 8; then q = f/.(j+1) by TARSKI:def 1; hence contradiction by A3,A6,A7,A10,A27,SPPOL_1:24; end; then i1 <= j by A24,NAT_1:29; hence i1 <= i2 by A20,AXIOMS:22; assume A30: i1 = i2; not p in LSeg(f/.j,q) by A3,A10,Th16; then not LE p,q,f/.j,f/.(j+1) by JORDAN3:65; then LT q,p,f/.j,f/.(j+1) by A2,A6,A11,A18,A21,A23,A27,A28,A30,AXIOMS:21,JORDAN3:63; hence LE q,p,f/.i1,f/.(i1+1) by A18,A21,A23,A28,A30,AXIOMS:21,JORDAN3:def 7; end; hence LE q, p, L~f, f/.1, f/.len f by A2,A8,A9,A10,JORDAN5C:30; end; begin :: Special circular theorem Th41: for f being non constant standard special_circular_sequence holds LeftComp f is open & RightComp f is open proof let f be non constant standard special_circular_sequence; L~f is closed by SPPOL_1:49; then A1: (L~f)` is open by TOPS_1:29; LeftComp f is_a_component_of (L~f)` by GOBOARD9:def 1; then LeftComp f is_a_component_of (L~f)`; hence LeftComp f is open by A1,Th18; RightComp f is_a_component_of (L~f)` by GOBOARD9:def 2; then RightComp f is_a_component_of (L~f)`; hence RightComp f is open by A1,Th18; end; definition let f be non constant standard special_circular_sequence; cluster L~f -> non vertical non horizontal; coherence proof W-bound L~f <> E-bound L~f by TOPREAL5:23; hence L~f is non vertical by SPRECT_1:17; S-bound L~f <> N-bound L~f by TOPREAL5:22; hence L~f is non horizontal by SPRECT_1:18; end; cluster LeftComp f -> being_Region; coherence proof thus LeftComp f is open by Th41; LeftComp f is_a_component_of (L~f)` by GOBOARD9:def 1; then consider A being Subset of (TOP-REAL 2)|(L~f)` such that A1: A = LeftComp f and A2: A is_a_component_of (TOP-REAL 2)|(L~f)` by CONNSP_1:def 6; A is connected by A2,CONNSP_1:def 5; hence LeftComp f is connected by A1,CONNSP_1:24; end; cluster RightComp f -> being_Region; coherence proof thus RightComp f is open by Th41; RightComp f is_a_component_of (L~f)` by GOBOARD9:def 2; then consider A being Subset of (TOP-REAL 2)|(L~f)` such that A3: A = RightComp f and A4: A is_a_component_of (TOP-REAL 2)|(L~f)` by CONNSP_1:def 6; A is connected by A4,CONNSP_1:def 5; hence RightComp f is connected by A3,CONNSP_1:24; end; end; theorem Th42: for f being non constant standard special_circular_sequence holds RightComp f misses L~f proof let f be non constant standard special_circular_sequence; (L~f)` =LeftComp f \/ RightComp f by GOBRD12:11; then RightComp f c= (L~f)` by XBOOLE_1:7; hence RightComp f misses L~f by SUBSET_1:43; end; theorem Th43: for f being non constant standard special_circular_sequence holds LeftComp f misses L~f proof let f be non constant standard special_circular_sequence; (L~f)` =LeftComp f \/ RightComp f by GOBRD12:11; then LeftComp f c= (L~f)` by XBOOLE_1:7; hence LeftComp f misses L~f by SUBSET_1:43; end; theorem Th44: for f being non constant standard special_circular_sequence holds i_w_n f < i_e_n f proof let f be non constant standard special_circular_sequence; set G = GoB f; A1: width G > 1 by GOBOARD7:35; A2: i_w_n f <= len G by JORDAN5D:47; A3: G*(i_w_n f,width G) = N-min L~f by JORDAN5D:def 7; A4: 1 <= i_e_n f by JORDAN5D:47; A5: G*(i_e_n f,width G) = N-max L~f by JORDAN5D:def 8; A6: (N-min L~f)`1 < (N-max L~f)`1 by SPRECT_2:55; then A7: i_w_n f <> i_e_n f by A5,JORDAN5D:def 7; assume i_w_n f >= i_e_n f; then i_w_n f > i_e_n f by A7,AXIOMS:21; hence contradiction by A1,A2,A3,A4,A5,A6,GOBOARD5:4; end; theorem Th45: for f being non constant standard special_circular_sequence ex i st 1 <= i & i < len GoB f & N-min L~f = (GoB f)*(i,width GoB f) proof let f be non constant standard special_circular_sequence; take i = i_w_n f; thus 1 <= i by JORDAN5D:47; A1: i_e_n f <= len GoB f by JORDAN5D:47; i < i_e_n f by Th44; hence i < len GoB f by A1,AXIOMS:22; thus N-min L~f = (GoB f)*(i,width GoB f) by JORDAN5D:def 7; end; theorem Th46: for f being clockwise_oriented (non constant standard special_circular_sequence) st i in dom GoB f & f/.1 = (GoB f)*(i,width GoB f) & f/.1 = N-min L~f holds f/.2 = (GoB f)*(i+1,width GoB f) & f/.(len f -' 1) = (GoB f)*(i,width GoB f -' 1) proof let f be clockwise_oriented (non constant standard special_circular_sequence) such that A1: i in dom GoB f and A2: f/.1 = (GoB f)*(i,width GoB f) and A3: f/.1 = N-min L~f; A4: f/.2 in N-most L~f by A3,SPRECT_2:34; A5: 1 <= width GoB f by GOBRD11:34; A6: 4 < len f by GOBOARD7:36; then A7: 1+1 <= len f by AXIOMS:22; then A8: 1+1 in dom f by FINSEQ_3:27; then consider i1,j1 being Nat such that A9: [i1,j1] in Indices GoB f and A10: f/.2 = (GoB f)*(i1,j1) by GOBOARD2:25; A11: 1 <= len f by A6,AXIOMS:22; then A12: 1 in dom f by FINSEQ_3:27; A13: 1 <= i & i <= len GoB f by A1,FINSEQ_3:27; then A14: [i,width GoB f] in Indices GoB f by A5,GOBOARD7:10; A15: 1 <= j1 & j1 <= width GoB f by A9,GOBOARD5:1; A16: 1 <= i1 & i1 <= len GoB f by A9,GOBOARD5:1; now assume A17: j1 < width GoB f; A18: (GoB f)*(i1,width GoB f)`2 = (GoB f)*(1,width GoB f)`2 by A5,A16,GOBOARD5:2 .= N-bound L~f by JORDAN5D:42; (f/.2)`2 = (N-min L~f)`2 by A4,PSCOMP_1:98 .= N-bound L~f by PSCOMP_1:94; hence contradiction by A10,A15,A16,A17,A18,GOBOARD5:5; end; then A19: j1 = width GoB f by A15,AXIOMS:21; A20: abs(i-i1)+0 = abs(i-i1)+abs(0) by ABSVALUE:7 .=abs(i-i1)+abs(width GoB f-width GoB f) by XCMPLX_1:14 .= 1 by A2,A8,A9,A10,A12,A14,A19,GOBOARD5:13; now assume i > i1; then (f/.2)`1 < (N-min L~f)`1 by A2,A3,A10,A13,A15,A16,A19,GOBOARD5:4; hence contradiction by A4,PSCOMP_1:98; end; hence A21: f/.2 = (GoB f)*(i+1,width GoB f) by A10,A19,A20,GOBOARD1:1; A22: f/.len f = f/.1 by FINSEQ_6:def 1; A23: len f -' 1 + 1 = len f by A11,AMI_5:4; A24: 1 <= len f -' 1 & len f -' 1 <= len f by A7,JORDAN3:7,12; then A25: len f -' 1 in dom f by FINSEQ_3:27; then consider i2,j2 being Nat such that A26: [i2,j2] in Indices GoB f and A27: f/.(len f -' 1) = (GoB f)*(i2,j2) by GOBOARD2:25; A28: 1 <= i2 & i2 <= len GoB f by A26,GOBOARD5:1; A29: 1 <= j2 & j2 <= width GoB f by A26,GOBOARD5:1; len f in dom f by A11,FINSEQ_3:27; then A30: abs(i2-i)+abs(j2-width GoB f) = 1 by A2,A14,A22,A23,A25,A26,A27,GOBOARD5:13; per cases by A30,GOBOARD1:2; suppose that A31: abs(i2-i)=1 and A32: j2=width GoB f; A33: (f/.(len f -' 1))`2 = ((GoB f)*(1,width GoB f))`2 by A5,A27,A28,A32, GOBOARD5:2 .= (N-min L~f)`2 by A2,A3,A5,A13,GOBOARD5:2 .= N-bound L~f by PSCOMP_1:94; f/.(len f -' 1) in L~f by A7,A25,GOBOARD1:16; then A34: f/.(len f -' 1) in N-most L~f by A33,SPRECT_2:14; now per cases by A31,GOBOARD1:1; suppose i > i2; then (f/.(len f -' 1))`1 < (N-min L~f)`1 by A2,A3,A5,A13,A27,A28,A32,GOBOARD5:4; hence contradiction by A34,PSCOMP_1:98; suppose i+1 = i2; then 2 >= len f -' 1 by A21,A24,A27,A32,GOBOARD7:39; then 2+1 >= len f by Th5; hence contradiction by A6,AXIOMS:22; end; hence thesis; suppose that A35: abs(j2-width GoB f)=1 and A36: i2=i; j2 < width GoB f & width GoB f = j2+1 by A29,A35,GOBOARD1:1; hence f/.(len f -' 1) = (GoB f)*(i,width GoB f -' 1) by A27,A36,BINARITH:39; end; theorem for f being non constant standard special_circular_sequence st 1 <= i & i < j & j <= len f & f/.1 in L~mid(f,i,j) holds i = 1 or j = len f proof let f be non constant standard special_circular_sequence such that A1: 1 <= i and A2: i < j and A3: j <= len f; assume f/.1 in L~mid(f,i,j); then consider n such that A4: 1 <= n & n+1 <= len mid(f,i,j) and A5: f/.1 in LSeg(mid(f,i,j),n) by SPPOL_2:13; assume that A6: i <> 1 and A7: j <> len f; n < len mid(f,i,j) by A4,NAT_1:38; then A8: n<j-'i+1 by A1,A2,A3,JORDAN4:20; then A9: LSeg(mid(f,i,j),n)=LSeg(f,n+i-'1) by A1,A2,A3,A4,JORDAN4:31; A10: len f > 4 by GOBOARD7:36; then 1+1 <= len f by AXIOMS:22; then f/.1 in LSeg(f,1) by TOPREAL1:27; then A11: f/.1 in LSeg(f,1) /\ LSeg(f,n+i-'1) by A5,A9,XBOOLE_0:def 3; then A12: LSeg(f,1) meets LSeg(f,n+i-'1) by XBOOLE_0:4; per cases by A12,GOBOARD5:def 4; suppose 1+1 >= n+i-'1; then A13: n+i <= 2+1 by Th5; n+i >= i+1 by A4,AXIOMS:24; then i+1 <= 2+1 by A13,AXIOMS:22; then A14: i <= 2 by REAL_1:53; i > 1 by A1,A6,AXIOMS:21; then i >= 1+1 by NAT_1:38; then A15: i = 2 by A14,AXIOMS:21; then n <= 1 by A13,REAL_1:53; then n = 1 by A4,AXIOMS:21; then A16: n+i-'1 = 2 by A15,BINARITH:39; 1+2 <= len f by A10,AXIOMS:22; then LSeg(f,1) /\ LSeg(f,1+1) = {f/.(1+1)} by TOPREAL1:def 8; then A17: f/.1 = f/.2 by A11,A16,TARSKI:def 1; 2 < len f by A10,AXIOMS:22; hence contradiction by A17,GOBOARD7:38; suppose A18: n+i-'1+1 >= len f; n <= n+i by NAT_1:29; then 1 <= n+i by A4,AXIOMS:22; then A19: len f <= n+i by A18,AMI_5:4; A20: j < len f by A3,A7,AXIOMS:21; j-'i+1+i = j-'i+i+1 by XCMPLX_1:1 .= j+1 by A2,AMI_5:4; then n+i < j+1 by A8,REAL_1:53; then n+i <= j by NAT_1:38; hence contradiction by A19,A20,AXIOMS:22; end; theorem for f being clockwise_oriented (non constant standard special_circular_sequence) st f/.1 = N-min L~f holds LSeg(f/.1,f/.2) c= L~SpStSeq L~f proof let f be clockwise_oriented (non constant standard special_circular_sequence); assume A1: f/.1 = N-min L~f; then A2: f/.1 in LSeg(NW-corner L~f,NE-corner L~f) by Th28; A3: f/.2 in N-most L~f by A1,SPRECT_2:34; N-most L~f c= LSeg(NW-corner L~f,NE-corner L~f) by Th27; then A4: LSeg(f/.1,f/.2) c= LSeg(NW-corner L~f,NE-corner L~f) by A2,A3,TOPREAL1:12; LSeg(NW-corner L~f,NE-corner L~f) c= L~SpStSeq L~f by Th26; hence LSeg(f/.1,f/.2) c= L~SpStSeq L~f by A4,XBOOLE_1:1; end; begin :: Rectangular theorem Th49: for f being rectangular FinSequence of TOP-REAL 2, p being Point of TOP-REAL 2 st p in L~f holds p`1 = W-bound L~f or p`1 = E-bound L~f or p`2 = S-bound L~f or p`2 = N-bound L~f proof let f be rectangular FinSequence of TOP-REAL 2, p be Point of TOP-REAL 2 such that A1: p in L~f; consider D being non vertical non horizontal non empty compact Subset of TOP-REAL 2 such that A2: f = SpStSeq D by SPRECT_1:def 2; L~f = (LSeg(NW-corner D,NE-corner D) \/ LSeg(NE-corner D,SE-corner D)) \/ (LSeg(SE-corner D,SW-corner D) \/ LSeg(SW-corner D,NW-corner D)) by A2,SPRECT_1:43; then A3: p in LSeg(NW-corner D,NE-corner D) \/ LSeg(NE-corner D,SE-corner D ) or p in LSeg(SE-corner D,SW-corner D) \/ LSeg(SW-corner D,NW-corner D) by A1,XBOOLE_0:def 2; per cases by A3,XBOOLE_0:def 2; suppose A4: p in LSeg(NW-corner D,NE-corner D); N-bound L~SpStSeq D = N-bound D by SPRECT_1:68; then (NW-corner D)`2 = N-bound L~f & (NE-corner D)`2 = N-bound L~f by A2,PSCOMP_1:75,77; hence thesis by A4,GOBOARD7:6; suppose A5: p in LSeg(NE-corner D,SE-corner D); E-bound L~SpStSeq D = E-bound D by SPRECT_1:69; then (NE-corner D)`1 = E-bound L~f & (SE-corner D)`1 = E-bound L~f by A2,PSCOMP_1:76,78; hence thesis by A5,GOBOARD7:5; suppose A6: p in LSeg(SE-corner D,SW-corner D); S-bound L~SpStSeq D = S-bound D by SPRECT_1:67; then (SE-corner D)`2 = S-bound L~f & (SW-corner D)`2 = S-bound L~f by A2,PSCOMP_1:73,79; hence thesis by A6,GOBOARD7:6; suppose A7: p in LSeg(SW-corner D,NW-corner D); W-bound L~SpStSeq D = W-bound D by SPRECT_1:66; then (SW-corner D)`1 = W-bound L~f & (NW-corner D)`1 = W-bound L~f by A2,PSCOMP_1:72,74; hence thesis by A7,GOBOARD7:5; end; definition cluster rectangular special_circular_sequence; existence proof consider C being non empty compact non vertical non horizontal Subset of TOP-REAL2; SpStSeq C is special_circular_sequence; hence thesis; end; end; theorem Th50: for f being rectangular special_circular_sequence, g being S-Sequence_in_R2 st g/.1 in LeftComp f & g/.len g in RightComp f holds L~f meets L~g proof let f be rectangular special_circular_sequence, g be S-Sequence_in_R2 such that A1: g/.1 in LeftComp f and A2: g/.len g in RightComp f; assume L~f misses L~g; then L~g c= (L~f)` by SUBSET_1:43; then A3: L~g c= LeftComp f \/ RightComp f by GOBRD12:11; A4: LeftComp f is open & RightComp f is open by Th41; A5: len g >= 2 by TOPREAL1:def 10; then g/.1 in L~g by JORDAN3:34; then g/.1 in LeftComp f /\ L~g by A1,XBOOLE_0:def 3; then A6:LeftComp f meets L~g by XBOOLE_0:4; g/.len g in L~g by A5,JORDAN3:34; then g/.len g in RightComp f /\ L~g by A2,XBOOLE_0:def 3; then A7:RightComp f meets L~g by XBOOLE_0:4; LeftComp f misses RightComp f by SPRECT_1:96; then A8: L~g is not connected by A3,A4,A6,A7,TOPREAL5:4; L~g is_an_arc_of g/.1,g/.len g by TOPREAL1:31; hence contradiction by A8,JORDAN6:11; end; theorem Th51: for f being rectangular special_circular_sequence holds SpStSeq L~f = f proof let f be rectangular special_circular_sequence; A1: SpStSeq L~f = <*NW-corner L~f,NE-corner L~f,SE-corner L~f*>^ <*SW-corner L~f,NW-corner L~f*> by SPRECT_1:def 1; set C = L~f, g = SpStSeq C; consider D being non vertical non horizontal non empty compact Subset of TOP-REAL 2 such that A2: f = SpStSeq D by SPRECT_1:def 2; A3: 5 = len f by SPRECT_1:90; A4: len g = len<*NW-corner L~f,NE-corner L~f,SE-corner L~f*> +len<*SW-corner L~f,NW-corner L~f*> by A1,FINSEQ_1:35 .= 3+len<*SW-corner L~f,NW-corner L~f*> by FINSEQ_1:62 .= 3+2 by FINSEQ_1:61; then A5: dom f = dom g by A3,FINSEQ_3:31; for i st i in dom f holds f/.i = g/.i proof let i; assume i in dom f; then A6: 0 <> i & i <= len f by FINSEQ_3:27; A7: f/.1 = W-max C by SPRECT_1:91 .= NW-corner D by A2,SPRECT_1:83 .= NW-corner C by A2,SPRECT_1:70 .= g/.1 by SPRECT_1:37; per cases by A3,A6,CQC_THE1:6; suppose i = 1; hence thesis by A7; suppose A8: i = 2; hence f/.i = E-max C by SPRECT_1:92 .= NE-corner D by A2,SPRECT_1:87 .= NE-corner C by A2,SPRECT_1:71 .= g/.i by A8,SPRECT_1:38; suppose A9: i = 3; hence f/.i = E-min C by SPRECT_1:93 .= SE-corner D by A2,SPRECT_1:86 .= SE-corner C by A2,SPRECT_1:73 .= g/.i by A9,SPRECT_1:39; suppose A10: i = 4; hence f/.i = W-min C by SPRECT_1:94 .= SW-corner D by A2,SPRECT_1:82 .= SW-corner C by A2,SPRECT_1:72 .= g/.i by A10,SPRECT_1:40; suppose A11: i = 5; hence f/.i = f/.1 by A3,FINSEQ_6:def 1 .= g/.i by A4,A7,A11,FINSEQ_6:def 1; end; hence f = g by A5,FINSEQ_5:13; end; theorem Th52: for f being rectangular special_circular_sequence holds L~f = { p where p is Point of TOP-REAL 2: p`1 = W-bound L~f & p`2 <= N-bound L~f & p`2 >= S-bound L~f or p`1 <= E-bound L~f & p`1 >= W-bound L~f & p`2 = N-bound L~f or p`1 <= E-bound L~f & p`1 >= W-bound L~f & p`2 = S-bound L~f or p`1 = E-bound L~f & p`2 <= N-bound L~f & p`2 >= S-bound L~f} proof let f be rectangular special_circular_sequence; set C = L~f, E = { p : p`1 = E-bound C & p`2 <= N-bound C & p`2 >= S-bound C}, S = { p : p`1 <= E-bound C & p`1 >= W-bound C & p`2 = S-bound C}, N = { p : p`1 <= E-bound C & p`1 >= W-bound C & p`2 = N-bound C}, W = { p : p`1 = W-bound C & p`2 <= N-bound C & p`2 >= S-bound C}; A1: C = L~SpStSeq C by Th51; A2: LSeg(SE-corner C, NE-corner C) = E by SPRECT_1:25; A3: LSeg(SW-corner C, SE-corner C) = S by SPRECT_1:26; A4: LSeg(NW-corner C, NE-corner C) = N by SPRECT_1:27; A5: LSeg(SW-corner C, NW-corner C) = W by SPRECT_1:28; thus C c= { p where p is Point of TOP-REAL 2: p`1 = W-bound C & p`2 <= N-bound C & p`2 >= S-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = N-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = S-bound C or p`1 = E-bound C & p`2 <= N-bound C & p`2 >= S-bound C} proof let x be set; assume A6: x in C; then reconsider q=x as Point of TOP-REAL 2; q in (LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C)) \/ (LSeg(SE-corner C,SW-corner C) \/ LSeg(SW-corner C,NW-corner C)) by A1,A6,SPRECT_1:43; then q in (LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C)) or q in (LSeg(SE-corner C,SW-corner C) \/ LSeg(SW-corner C,NW-corner C)) by XBOOLE_0:def 2; then q in LSeg(NW-corner C,NE-corner C) or q in LSeg(NE-corner C,SE-corner C) or q in LSeg(SE-corner C,SW-corner C) or q in LSeg(SW-corner C,NW-corner C) by XBOOLE_0:def 2; then (ex p st x = p & p`1 = E-bound C & p`2 <= N-bound C & p`2 >= S-bound C) or (ex p st x = p & p`1 <= E-bound C & p`1 >= W-bound C & p`2 = S-bound C) or (ex p st x = p & p`1 <= E-bound C & p`1 >= W-bound C & p`2 = N-bound C) or (ex p st x = p & p`1 = W-bound C & p`2 <= N-bound C & p`2 >= S-bound C) by A2,A3,A4,A5; hence x in { p where p is Point of TOP-REAL 2: p`1 = W-bound C & p`2 <= N-bound C & p`2 >= S-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = N-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = S-bound C or p`1 = E-bound C & p`2 <= N-bound C & p`2 >= S-bound C}; end; let x be set; assume x in { p where p is Point of TOP-REAL 2: p`1 = W-bound C & p`2 <= N-bound C & p`2 >= S-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = N-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = S-bound C or p`1 = E-bound C & p`2 <= N-bound C & p`2 >= S-bound C}; then ex p st x = p & (p`1 = W-bound C & p`2 <= N-bound C & p`2 >= S-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = N-bound C or p`1 <= E-bound C & p`1 >= W-bound C & p`2 = S-bound C or p`1 = E-bound C & p`2 <= N-bound C & p`2 >= S-bound C); then x in LSeg(NW-corner C,NE-corner C) or x in LSeg(NE-corner C,SE-corner C) or x in LSeg(SE-corner C,SW-corner C) or x in LSeg(SW-corner C,NW-corner C) by A2,A3,A4,A5; then x in (LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C)) or x in (LSeg(SE-corner C,SW-corner C) \/ LSeg(SW-corner C,NW-corner C)) by XBOOLE_0:def 2; then x in (LSeg(NW-corner C,NE-corner C) \/ LSeg(NE-corner C,SE-corner C)) \/ (LSeg(SE-corner C,SW-corner C) \/ LSeg(SW-corner C,NW-corner C)) by XBOOLE_0:def 2; hence x in C by A1,SPRECT_1:43; end; theorem Th53: for f being rectangular special_circular_sequence holds GoB f = (f/.4,f/.1)][(f/.3,f/.2) proof let f be rectangular special_circular_sequence; set G = (f/.4,f/.1)][(f/.3,f/.2), v1 = Incr X_axis f, v2 = Incr Y_axis f; A1: f/.1 = N-min L~f & f/.1 = W-max L~f by SPRECT_1:91; A2: f/.2 = N-max L~f & f/.2 = E-max L~f by SPRECT_1:92; A3: f/.3 = S-max L~f & f/.3 = E-min L~f by SPRECT_1:93; A4: f/.4 = S-min L~f & f/.4 = W-min L~f by SPRECT_1:94; A5: len f = 5 by SPRECT_1:90; set g = <*(f/.1)`1,(f/.2)`1*>, h = <*(f/.1)`1,(f/.2)`1*>^<*(f/.3)`1,(f/.4)`1,(f/.5)`1*>; A6: len g = 2 by FINSEQ_1:61; A7: len<*(f/.3)`1,(f/.4)`1,(f/.5)`1*> = 3 by FINSEQ_1:62; A8: len h = len <*(f/.1)`1,(f/.2)`1*> + len<*(f/.3)`1,(f/.4)`1,(f/.5)`1*> by FINSEQ_1:35 .= len <*(f/.1)`1,(f/.2)`1*> + 3 by FINSEQ_1:62 .= 2 + 3 by FINSEQ_1:61 .= len f by SPRECT_1:90; for n st n in dom h holds h.n = (f/.n)`1 proof let n; assume n in dom h; then 1 <= n & n <= 5 by A5,A8,FINSEQ_3:27; then A9: 1 <= n & (n=0 or n=1 or n=2 or n=3 or n=4 or n=5) by CQC_THE1:6; per cases by A9; suppose A10: n=1; then n in dom g by A6,FINSEQ_3:27; hence h.n = <*(f/.1)`1,(f/.2)`1*>.1 by A10,FINSEQ_1:def 7 .= (f/.n)`1 by A10,FINSEQ_1:61; suppose A11: n=2; then n in dom g by A6,FINSEQ_3:27; hence h.n = <*(f/.1)`1,(f/.2)`1*>.2 by A11,FINSEQ_1:def 7 .= (f/.n)`1 by A11,FINSEQ_1:61; suppose A12: n=3; hence h.n = h.(2+1) .= <*(f/.3)`1,(f/.4)`1,(f/.5)`1*>.1 by A6,A7,SCMFSA_7:10 .= (f/.n)`1 by A12,FINSEQ_1:62; suppose A13: n=4; hence h.n = h.(2+2) .= <*(f/.3)`1,(f/.4)`1,(f/.5)`1*>.2 by A6,A7,SCMFSA_7:10 .= (f/.n)`1 by A13,FINSEQ_1:62; suppose A14: n=5; hence h.n = h.(2+3) .= <*(f/.3)`1,(f/.4)`1,(f/.5)`1*>.3 by A6,A7,SCMFSA_7:10 .= (f/.n)`1 by A14,FINSEQ_1:62; end; then A15: X_axis f = h by A8,GOBOARD1:def 3; A16: dom g = {1,2} by FINSEQ_1:4,FINSEQ_3:29; A17: {(f/.3)`1,(f/.4)`1,(f/.5)`1} c= { (f/.1)`1,(f/.2)`1 } proof let x be set; assume A18: x in {(f/.3)`1,(f/.4)`1,(f/.5)`1}; per cases by A18,ENUMSET1:13; suppose x = (f/.3)`1; then x = (f/.2)`1 by A2,A3,PSCOMP_1:105; hence thesis by TARSKI:def 2; suppose x = (f/.4)`1; then x = (f/.1)`1 by A1,A4,PSCOMP_1:85; hence thesis by TARSKI:def 2; suppose x = (f/.5)`1; then x = (f/.1)`1 by A5,FINSEQ_6:def 1; hence thesis by TARSKI:def 2; end; A19: rng g = { (f/.1)`1,(f/.2)`1 } by FINSEQ_2:147; then A20: rng g = rng<*(f/.1)`1,(f/.2)`1*> \/ {(f/.3)`1,(f/.4)`1,(f/.5)`1} by A17,XBOOLE_1:12 .= rng<*(f/.1)`1,(f/.2)`1*> \/ rng<*(f/.3)`1,(f/.4)`1,(f/.5)`1*> by FINSEQ_2:148 .= rng X_axis f by A15,FINSEQ_1:44; A21: (f/.1)`1 < (f/.2)`1 by A1,A2,SPRECT_2:55; A22: len g = 2 by FINSEQ_1:61 .= Card rng X_axis f by A19,A20,A21,CARD_2:76; g is increasing proof let n,m such that A23: n in dom g and A24: m in dom g and A25: n<m; A26: g.1 = (f/.1)`1 & g.2 = (f/.2)`1 by FINSEQ_1:61; (n = 1 or n = 2) & (m = 1 or m = 2) by A16,A23,A24,TARSKI:def 2; hence g.n < g.m by A1,A2,A25,A26,SPRECT_2:55; end; then A27: v1 = <*(f/.1)`1,(f/.2)`1*> by A20,A22,GOBOARD2:def 2; set g = <*(f/.4)`2,(f/.5)`2*>, h = <*(f/.1)`2,(f/.2)`2,(f/.3)`2*>^<*(f/.4)`2,(f/.5)`2*>; A28: len g = 2 by FINSEQ_1:61; A29: len<*(f/.1)`2,(f/.2)`2,(f/.3)`2*> = 3 by FINSEQ_1:62; A30: len h = len <*(f/.1)`2,(f/.2)`2,(f/.3)`2*> + len<*(f/.4)`2,(f/.5)`2*> by FINSEQ_1:35 .= len <*(f/.4)`2,(f/.5)`2*> + 3 by FINSEQ_1:62 .= 2 + 3 by FINSEQ_1:61 .= len f by SPRECT_1:90; for n st n in dom h holds h.n = (f/.n)`2 proof let n; assume n in dom h; then 1 <= n & n <= 5 by A5,A30,FINSEQ_3:27; then A31: 1 <= n & (n=0 or n=1 or n=2 or n=3 or n=4 or n=5) by CQC_THE1:6; per cases by A31; suppose A32: n=1; then n in dom<*(f/.1)`2,(f/.2)`2,(f/.3)`2*> by A29,FINSEQ_3:27; hence h.n = <*(f/.1)`2,(f/.2)`2,(f/.3)`2*>.1 by A32,FINSEQ_1:def 7 .= (f/.n)`2 by A32,FINSEQ_1:62; suppose A33: n=2; then n in dom<*(f/.1)`2,(f/.2)`2,(f/.3)`2*> by A29,FINSEQ_3:27; hence h.n = <*(f/.1)`2,(f/.2)`2,(f/.3)`2*>.2 by A33,FINSEQ_1:def 7 .= (f/.n)`2 by A33,FINSEQ_1:62; suppose A34: n=3; then n in dom<*(f/.1)`2,(f/.2)`2,(f/.3)`2*> by A29,FINSEQ_3:27; hence h.n = <*(f/.1)`2,(f/.2)`2,(f/.3)`2*>.3 by A34,FINSEQ_1:def 7 .= (f/.n)`2 by A34,FINSEQ_1:62; suppose A35: n=4; hence h.n = h.(3+1) .= <*(f/.4)`2,(f/.5)`2*>.1 by A28,A29,SCMFSA_7:10 .= (f/.n)`2 by A35,FINSEQ_1:61; suppose A36: n=5; hence h.n = h.(2+3) .= <*(f/.4)`2,(f/.5)`2*>.2 by A28,A29,SCMFSA_7:10 .= (f/.n)`2 by A36,FINSEQ_1:61; end; then A37: Y_axis f = h by A30,GOBOARD1:def 4; A38: dom g = {1,2} by FINSEQ_1:4,FINSEQ_3:29; A39: f/.1 = f/.5 by A5,FINSEQ_6:def 1; A40: {(f/.1)`2,(f/.2)`2,(f/.3)`2} c= { (f/.4)`2,(f/.5)`2 } proof let x be set; assume A41: x in {(f/.1)`2,(f/.2)`2,(f/.3)`2}; per cases by A41,ENUMSET1:13; suppose x = (f/.1)`2; hence thesis by A39,TARSKI:def 2; suppose x = (f/.2)`2; then x = (f/.1)`2 by A1,A2,PSCOMP_1:95; hence thesis by A39,TARSKI:def 2; suppose x = (f/.3)`2; then x = (f/.4)`2 by A3,A4,PSCOMP_1:115; hence thesis by TARSKI:def 2; end; A42: rng g = { (f/.4)`2,(f/.5)`2 } by FINSEQ_2:147; then A43: rng g = {(f/.1)`2,(f/.2)`2,(f/.3)`2} \/ {(f/.4)`2,(f/.5)`2} by A40,XBOOLE_1:12 .= rng<*(f/.1)`2,(f/.2)`2,(f/.3)`2*> \/ {(f/.4)`2,(f/.5)`2} by FINSEQ_2:148 .= rng<*(f/.1)`2,(f/.2)`2,(f/.3)`2*> \/ rng<*(f/.4)`2,(f/.5)`2*> by FINSEQ_2:147 .= rng Y_axis f by A37,FINSEQ_1:44; A44: (f/.4)`2 < (f/.5)`2 by A1,A4,A39,SPRECT_2:61; A45: len g = 2 by FINSEQ_1:61 .= Card rng Y_axis f by A42,A43,A44,CARD_2:76; g is increasing proof let n,m such that A46: n in dom g and A47: m in dom g and A48: n<m; A49: g.1 = (f/.4)`2 & g.2 = (f/.5)`2 by FINSEQ_1:61; (n = 1 or n = 2) & (m = 1 or m = 2) by A38,A46,A47,TARSKI:def 2; hence g.n < g.m by A1,A4,A39,A48,A49,SPRECT_2:61; end; then A50: v2 = <*(f/.4)`2,(f/.1)`2*> by A39,A43,A45,GOBOARD2:def 2; A51: len G = 2 by MATRIX_2:3 .= len v1 by A27,FINSEQ_1:61; A52: width G = 2 by MATRIX_2:3 .= len v2 by A50,FINSEQ_1:61; A53: v1.1 = (f/.1)`1 by A27,FINSEQ_1:61; A54: v1.2 = (f/.2)`1 by A27,FINSEQ_1:61; A55: v2.1 = (f/.4)`2 by A50,FINSEQ_1:61; A56: v2.2 = (f/.1)`2 by A50,FINSEQ_1:61; A57: (f/.1)`1 = (f/.4)`1 by A1,A4,PSCOMP_1:85; A58: (f/.3)`1 = (f/.2)`1 by A2,A3,PSCOMP_1:105; A59: (f/.3)`2 = (f/.4)`2 by A3,A4,PSCOMP_1:115; A60: (f/.2)`2 = (f/.1)`2 by A1,A2,PSCOMP_1:95; for n,m st [n,m] in Indices G holds G*(n,m) = |[v1.n,v2.m]| proof let n,m; assume [n,m] in Indices G; then A61: [n,m]in { [1,1], [1,2],[2,1], [2,2]} by Th12; per cases by A61,ENUMSET1:18; suppose [n,m] = [1,1]; then A62: n = 1 & m = 1 by ZFMISC_1:33; hence G*(n,m) = f/.4 by MATRIX_2:6 .= |[v1.n,v2.m]| by A53,A55,A57,A62,EUCLID:57; suppose [n,m] = [1,2]; then A63: n = 1 & m = 2 by ZFMISC_1:33; hence G*(n,m) = f/.1 by MATRIX_2:6 .= |[v1.n,v2.m]| by A53,A56,A63,EUCLID:57; suppose [n,m] = [2,1]; then A64: n = 2 & m = 1 by ZFMISC_1:33; hence G*(n,m) = f/.3 by MATRIX_2:6 .= |[v1.n,v2.m]| by A54,A55,A58,A59,A64,EUCLID:57; suppose [n,m] = [2,2]; then A65: n = 2 & m = 2 by ZFMISC_1:33; hence G*(n,m) = f/.2 by MATRIX_2:6 .= |[v1.n,v2.m]| by A54,A56,A60,A65,EUCLID:57; end; then GoB(v1,v2) = G by A51,A52,GOBOARD2:def 1; hence thesis by GOBOARD2:def 3; end; theorem Th54: for f being rectangular special_circular_sequence holds LeftComp f = {p : not(W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f)} & RightComp f = {q : W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f} proof let f be rectangular special_circular_sequence; defpred U[Element of TOP-REAL 2] means not(W-bound L~f <= $1`1 & $1`1 <= E-bound L~f & S-bound L~f <= $1`2 & $1`2 <= N-bound L~f); defpred V[Element of TOP-REAL 2] means W-bound L~f < $1`1 & $1`1 < E-bound L~f & S-bound L~f < $1`2 & $1`2 < N-bound L~f; defpred W[Element of TOP-REAL 2] means $1`1 = W-bound L~f & $1`2 <= N-bound L~f & $1`2 >= S-bound L~f or $1`1 <= E-bound L~f & $1`1 >= W-bound L~f & $1`2 = N-bound L~f or $1`1 <= E-bound L~f & $1`1 >= W-bound L~f & $1`2 = S-bound L~f or $1`1 = E-bound L~f & $1`2 <= N-bound L~f & $1`2 >= S-bound L~f; set LC = {p : U[p] }, RC = {q : V[q] }, Lf = {p : W[p] }; A1: L~f = Lf by Th52; A2: W-bound L~f < E-bound L~f by SPRECT_1:33; A3: S-bound L~f < N-bound L~f by SPRECT_1:34; A4: LC is Subset of TOP-REAL 2 from SubsetD; A5: RC is Subset of TOP-REAL 2 from SubsetD; Lf is Subset of TOP-REAL 2 from SubsetD; then reconsider Lc'=LC,Rc'=RC,Lf as Subset of TOP-REAL 2 by A4,A5; reconsider Lc', Rc' as Subset of TOP-REAL 2; reconsider Lf as Subset of TOP-REAL 2; reconsider Lc=Lc', Rc=Rc' as Subset of (TOP-REAL 2)|Lf` by A2,A3,JORDAN1:44,46; reconsider Lc, Rc as Subset of (TOP-REAL 2)|Lf`; A6: LeftComp f is_a_component_of (L~f)` & RightComp f is_a_component_of (L~f)` by GOBOARD9:def 1,def 2; Rc = Rc'; then Lc is_a_component_of (TOP-REAL 2)|Lf` by A2,A3,JORDAN1:41; then A7: Lc' is_a_component_of Lf` by CONNSP_1:def 6; len f > 4 by GOBOARD7:36; then A8: 1+1 <= len f by AXIOMS:22; 1 < width GoB f by GOBOARD7:35; then A9: 1+1 <= width GoB f by NAT_1:38; 1 <= len GoB f by GOBOARD7:34; then A10: [1,1+1] in Indices GoB f by A9,GOBOARD7:10; A11: GoB f = (f/.4,f/.1)][(f/.3,f/.2) by Th53; then A12: f/.1 = (GoB f)*(1,1+1) by MATRIX_2:6; A13: 1+1 = len GoB f by A11,MATRIX_2:3; then A14: [1+1,1+1] in Indices GoB f by A9,GOBOARD7:10; A15: 1+1 = width GoB f by A11,MATRIX_2:3; A16: f/.(1+1) = (GoB f)*(1+1,1+1) by A11,MATRIX_2:6; then A17: left_cell(f,1) = cell(GoB f,1,1+1)by A8,A10,A12,A14,GOBOARD5:29; set p = 1/2*((GoB f)*(1,width GoB f)+(GoB f)*(1+1,width GoB f))+|[0,1]|, q = 1/2*((GoB f)*(1,width GoB f)+(GoB f)*(1+1,width GoB f)); A18: p in Int cell(GoB f,1,1+1) by A13,A15,GOBOARD6:35; A19: Int cell(GoB f,1,1+1) c= LeftComp f by A17,GOBOARD9:def 1; A20: p`2 = q`2+|[0,1]|`2 by TOPREAL3:7 .= q`2+1 by EUCLID:56; q`2 = (1/2*((GoB f)*(1,width GoB f)+f/.2))`2 by A11,A15,MATRIX_2:6 .= (1/2*(f/.1+f/.2))`2 by A11,A15,MATRIX_2:6 .= 1/2*(f/.1+f/.2)`2 by TOPREAL3:9 .= 1/2*((f/.1)`2+(f/.2)`2) by TOPREAL3:7 .= 1/2*((N-min L~f)`2+(f/.2)`2) by SPRECT_1:91 .= 1/2*((N-min L~f)`2+(N-max L~f)`2) by SPRECT_1:92 .= 1/2*(N-bound L~f+(N-max L~f)`2) by PSCOMP_1:94 .= 1/2*(N-bound L~f+N-bound L~f) by PSCOMP_1:94 .= 1/2*(2*N-bound L~f) by XCMPLX_1:11 .= N-bound L~f by XCMPLX_1:108; then p`2 > 0 + N-bound L~f by A20,REAL_1:67; then p in LC; then LC meets LeftComp f by A18,A19,XBOOLE_0:3; hence LeftComp f = LC by A1,A6,A7,GOBOARD9:3; Lc = Lc'; then Rc is_a_component_of (TOP-REAL 2)|Lf` by A2,A3,JORDAN1:41; then A21: Rc' is_a_component_of Lf` by CONNSP_1:def 6; A22: right_cell(f,1) = cell(GoB f,1,1) by A8,A10,A12,A14,A16,GOBOARD5:29; set p = 1/2*((GoB f)*(1,1)+(GoB f)*(2,2)); A23: p in Int cell(GoB f,1,1) by A13,A15,GOBOARD6:34; A24: Int cell(GoB f,1,1) c= RightComp f by A22,GOBOARD9:def 2; A25: p = 1/2*((GoB f)*(1,1)+f/.2) by A11,MATRIX_2:6 .= 1/2*(f/.4+f/.2) by A11,MATRIX_2:6; A26: 1/2*(W-bound L~f) + 1/2*(W-bound L~f) = 1/2*((W-bound L~f)+(W-bound L~f)) by XCMPLX_1:8 .= 1/2*(2*(W-bound L~f)) by XCMPLX_1:11 .= (W-bound L~f) by XCMPLX_1:108; A27: 1/2*(S-bound L~f) + 1/2*(S-bound L~f) = 1/2*((S-bound L~f)+(S-bound L~f)) by XCMPLX_1:8 .= 1/2*(2*(S-bound L~f)) by XCMPLX_1:11 .= (S-bound L~f) by XCMPLX_1:108; A28: 1/2*(N-bound L~f) + 1/2*(N-bound L~f) = 1/2*((N-bound L~f)+(N-bound L~f)) by XCMPLX_1:8 .= 1/2*(2*(N-bound L~f)) by XCMPLX_1:11 .= (N-bound L~f) by XCMPLX_1:108; A29: 1/2*(E-bound L~f) + 1/2*(E-bound L~f) = 1/2*((E-bound L~f)+(E-bound L~f)) by XCMPLX_1:8 .= 1/2*(2*(E-bound L~f)) by XCMPLX_1:11 .= (E-bound L~f) by XCMPLX_1:108; A30: p`1 = 1/2*(f/.4+f/.2)`1 by A25,TOPREAL3:9 .= 1/2*((f/.4)`1+(f/.2)`1) by TOPREAL3:7 .= 1/2*(f/.4)`1+ 1/2*(f/.2)`1 by XCMPLX_1:8; A31: p`2 = 1/2*(f/.4+f/.2)`2 by A25,TOPREAL3:9 .= 1/2*((f/.4)`2+(f/.2)`2) by TOPREAL3:7 .= 1/2*(f/.4)`2+ 1/2*(f/.2)`2 by XCMPLX_1:8; A32: (f/.4)`1 = (W-min L~f)`1 by SPRECT_1:94 .= W-bound L~f by PSCOMP_1:84; A33: (f/.2)`1 = (E-max L~f)`1 by SPRECT_1:92 .= E-bound L~f by PSCOMP_1:104; A34: (f/.4)`2 = (S-min L~f)`2 by SPRECT_1:94 .= S-bound L~f by PSCOMP_1:114; A35: (f/.2)`2 = (N-max L~f)`2 by SPRECT_1:92 .= N-bound L~f by PSCOMP_1:94; (f/.2)`1 > W-bound L~f by A33,SPRECT_1:33; then 1/2*(f/.2)`1 > 1/2*W-bound L~f by REAL_1:70; then A36: W-bound L~f < p`1 by A26,A30,A32,REAL_1:53; (f/.4)`1 < E-bound L~f by A32,SPRECT_1:33; then 1/2*(f/.4)`1 < 1/2*E-bound L~f by REAL_1:70; then A37: p`1 < E-bound L~f by A29,A30,A33,REAL_1:53; (f/.2)`2 > S-bound L~f by A35,SPRECT_1:34; then 1/2*(f/.2)`2 > 1/2*S-bound L~f by REAL_1:70; then A38: S-bound L~f < p`2 by A27,A31,A34,REAL_1:53; (f/.4)`2 < N-bound L~f by A34,SPRECT_1:34; then 1/2*(f/.4)`2 < 1/2*N-bound L~f by REAL_1:70; then p`2 < N-bound L~f by A28,A31,A35,REAL_1:53; then p in RC by A36,A37,A38; then RC meets RightComp f by A23,A24,XBOOLE_0:3; hence RightComp f = RC by A1,A6,A21,GOBOARD9:3; end; definition cluster clockwise_oriented (rectangular special_circular_sequence); existence proof consider C being non empty compact non vertical non horizontal Subset of TOP-REAL2; SpStSeq C is clockwise_oriented; hence thesis; end; end; definition cluster -> clockwise_oriented (rectangular special_circular_sequence); coherence proof let f be rectangular special_circular_sequence; consider D being non vertical non horizontal non empty compact Subset of TOP-REAL 2 such that A1: f = SpStSeq D by SPRECT_1:def 2; thus thesis by A1; end; end; theorem for f being rectangular special_circular_sequence, g being S-Sequence_in_R2 st g/.1 in LeftComp f & g/.len g in RightComp f holds Last_Point(L~g,g/.1,g/.len g,L~f) <> NW-corner L~f proof let f be rectangular special_circular_sequence, g be S-Sequence_in_R2 such that A1: g/.1 in LeftComp f and A2: g/.len g in RightComp f; A3: L~f meets L~g by A1,A2,Th50; A4: L~f is closed by SPPOL_1:49; L~f is closed & L~g is closed by SPPOL_1:49; then A5: L~f /\ L~g is closed by TOPS_1:35; A6: L~g is_an_arc_of g/.1, g/.len g by TOPREAL1:31; set nw = NW-corner L~f, inw = Index(nw,g); assume A7: Last_Point(L~g,g/.1,g/.len g,L~f) = NW-corner L~f; then A8: nw in L~g /\ L~f by A3,A5,A6,JORDAN5C:def 2; then A9: nw in L~g by XBOOLE_0:def 3; A10: L~f misses RightComp f by Th42; A11: nw in L~f by A8,XBOOLE_0:def 3; A12: len g in dom g by FINSEQ_5:6; then g.len g = g/.len g by FINSEQ_4:def 4; then A13: nw <> g.len g by A2,A10,A11,XBOOLE_0:3; A14: inw < len g by A9,JORDAN3:41; then A15: 1 <= inw & inw+1 <= len g by A9,JORDAN3:41,NAT_1:38; A16: nw in LSeg(g,inw) by A9,JORDAN3:42; A17: 1 <= inw+1 by NAT_1:29; then A18: inw+1 in dom g by A15,FINSEQ_3:27; A19: now assume nw <> g.(inw+1); then A20: nw <> g/.(inw+1) by A18,FINSEQ_4:def 4; A21: len g >= 1 by A15,A17,AXIOMS:22; per cases; suppose A22: g/.(inw+1) in L~f; then inw+1 <> len g by A2,A10,XBOOLE_0:3; then inw+1 < len g by A15,AXIOMS:21; then A23: inw+1+1 <= len g by NAT_1:38; then g/.(inw+1) in LSeg(g,inw+1) by A17,TOPREAL1:27; then inw >= inw+1 by A3,A4,A7,A15,A16,A17,A20,A22,A23,JORDAN5C:28; hence contradiction by REAL_1:69; suppose not g/.(inw+1) in L~f; then g/.(inw+1) in (L~f)` by SUBSET_1:50; then A24: g/.(inw+1) in LeftComp f \/ RightComp f by GOBRD12:11; A25: now A26: RightComp f = {q : W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f} by Th54; assume g/.(inw+1) in RightComp f; then A27: ex q st g/.(inw+1) = q & W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f by A26; A28: LSeg(g,inw) = LSeg(g/.inw,g/.(inw+1)) by A15,TOPREAL1:def 5; LSeg(g,inw) is vertical or LSeg(g,inw) is horizontal by SPPOL_1:41; then (g/.(inw+1))`1 = nw`1 or (g/.(inw+1))`2 = nw`2 by A16,A28,Th19,Th20; hence contradiction by A27,PSCOMP_1:74,75; end; then A29: g/.(inw+1) in LeftComp f by A24,XBOOLE_0:def 2; A30: inw+1<len g by A2,A15,A25,AXIOMS:21; reconsider m = mid(g,inw+1,len g) as S-Sequence_in_R2 by A2,A15,A17,A21,A25,JORDAN3:39; A31: m/.1 in LeftComp f by A12,A18,A29,SPRECT_2:12; m/.len m in RightComp f by A2,A12,A18,SPRECT_2:13; then L~f meets L~m by A31,Th50; then consider q being set such that A32: q in L~f and A33: q in L~m by XBOOLE_0:3; reconsider q as Point of TOP-REAL 2 by A33; consider i such that A34: 1 <= i & i+1 <= len m and A35: q in LSeg(m,i) by A33,SPPOL_2:13; A36: len m = len g-'(inw+1)+1 by A15,A17,JORDAN4:20; i < len m by A34,NAT_1:38; then A37: LSeg(m,i)=LSeg(g,i+(inw+1)-'1) by A17,A30,A34,A36,JORDAN4:31; set j = i+(inw+1)-'1; A38: j = i+inw+1-'1 by XCMPLX_1:1 .= i+inw by BINARITH:39; inw >= 0 by NAT_1:18; then A39: 0+1 <= j by A34,A38,REAL_1:55; len m = len g -' inw by A14,A36,NAT_2:9; then len m + inw = len g by A14,AMI_5:4; then i+1 + inw <= len g by A34,AXIOMS:24; then A40: j + 1 <= len g by A38,XCMPLX_1:1; A41: j >= inw+1 by A34,A38,AXIOMS:24; now assume nw = q; then A42: nw in LSeg(g,inw) /\ LSeg(g,j) by A16,A35,A37,XBOOLE_0:def 3; then A43: LSeg(g,inw) meets LSeg(g,j) by XBOOLE_0:4; per cases by A41,AXIOMS:21; suppose A44: inw+1 = j; inw+1+1 <= len g by A30,NAT_1:38; then inw + (1+1) <= len g by XCMPLX_1:1; then LSeg(g,inw) /\ LSeg(g,inw+1) = {g/.(inw+1)} by A15,TOPREAL1:def 8; hence contradiction by A20,A42,A44,TARSKI:def 1; suppose inw+1 < j; hence contradiction by A43,TOPREAL1:def 9; end; then inw >= j by A3,A4,A7,A15,A16,A32,A35,A37,A39,A40,JORDAN5C:28; then inw >= inw+1 by A41,AXIOMS:22; hence contradiction by REAL_1:69; end; then A45: inw+1 < len g by A13,A15,AXIOMS:21; then A46: inw+1+1 <= len g by NAT_1:38; A47: 1 <= inw+1+1 by NAT_1:29; then A48: inw+1+1 in dom g by A46,FINSEQ_3:27; g/.(inw+1) in LSeg(g,inw+1) by A17,A46,TOPREAL1:27; then A49: nw in LSeg(g,inw+1) by A18,A19,FINSEQ_4:def 4; inw+1 < inw+1+1 by NAT_1:38; then A50: nw <> g.(inw+1+1) by A18,A19,A48,FUNCT_1:def 8; then A51: nw <> g/.(inw+1+1) by A48,FINSEQ_4:def 4; A52: len g >= 1 by A46,A47,AXIOMS:22; per cases; suppose A53: g/.(inw+1+1) in L~f; then inw+1+1 <> len g by A2,A10,XBOOLE_0:3; then inw+1+1 < len g by A46,AXIOMS:21; then A54: inw+1+1+1 <= len g by NAT_1:38; then A55: g/.(inw+1+1) in LSeg(g,inw+1+1) by A47,TOPREAL1:27; nw <> g/.(inw+1+1) by A48,A50,FINSEQ_4:def 4; then inw+1 >= inw+1+1 by A3,A4,A7,A17,A46,A47,A49,A53,A54,A55,JORDAN5C:28; hence contradiction by REAL_1:69; suppose not g/.(inw+1+1) in L~f; then g/.(inw+1+1) in (L~f)` by SUBSET_1:50; then A56: g/.(inw+1+1) in LeftComp f \/ RightComp f by GOBRD12:11; A57: now A58: RightComp f = {q : W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f} by Th54; assume g/.(inw+1+1) in RightComp f; then A59: ex q st g/.(inw+1+1) = q & W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f by A58; A60: LSeg(g,inw+1) = LSeg(g/.(inw+1),g/.(inw+1+1)) by A17,A46,TOPREAL1:def 5; LSeg(g,inw+1) is vertical or LSeg(g,inw+1) is horizontal by SPPOL_1:41; then (g/.(inw+1+1))`1 = nw`1 or (g/.(inw+1+1))`2 = nw`2 by A49,A60,Th19,Th20; hence contradiction by A59,PSCOMP_1:74,75; end; then A61: g/.(inw+1+1) in LeftComp f by A56,XBOOLE_0:def 2; A62: inw+1+1<len g by A2,A46,A57,AXIOMS:21; reconsider m = mid(g,inw+1+1,len g) as S-Sequence_in_R2 by A2,A46,A47,A52,A57,JORDAN3:39; A63: m/.1 in LeftComp f by A12,A48,A61,SPRECT_2:12; m/.len m in RightComp f by A2,A12,A48,SPRECT_2:13; then L~f meets L~m by A63,Th50; then consider q being set such that A64: q in L~f and A65: q in L~m by XBOOLE_0:3; reconsider q as Point of TOP-REAL 2 by A65; consider i such that A66: 1 <= i & i+1 <= len m and A67: q in LSeg(m,i) by A65,SPPOL_2:13; A68: len m = len g-'(inw+1+1)+1 by A46,A47,JORDAN4:20; i < len m by A66,NAT_1:38; then A69: LSeg(m,i)=LSeg(g,i+(inw+1+1)-'1) by A47,A62,A66,A68,JORDAN4:31; set j = i+(inw+1+1)-'1; A70: j = i+(inw+1)+1-'1 by XCMPLX_1:1 .= i+inw+1+1-'1 by XCMPLX_1:1 .= i+inw+1 by BINARITH:39; then A71: 0+1 <= j by NAT_1:29; len m = len g -' (inw+1) by A45,A68,NAT_2:9; then len m + (inw+1) = len g by A15,AMI_5:4; then i+ 1 + (inw +1) <= len g by A66,AXIOMS:24; then i+ 1 + inw +1 <= len g by XCMPLX_1:1; then A72: j + 1 <= len g by A70,XCMPLX_1:1; j = i+(inw+1) by A70,XCMPLX_1:1; then A73: j >= inw+1+1 by A66,AXIOMS:24; now assume nw = q; then A74: nw in LSeg(g,inw+1) /\ LSeg(g,j) by A49,A67,A69,XBOOLE_0:def 3; then A75: LSeg(g,inw+1) meets LSeg(g,j) by XBOOLE_0:4; per cases by A73,AXIOMS:21; suppose A76: inw+1+1 = j; inw+1+1+1 <= len g by A62,NAT_1:38; then inw+1 + (1+1) <= len g by XCMPLX_1:1; then LSeg(g,inw+1) /\ LSeg(g,inw+1+1) = {g/.(inw+1+1)} by A17,TOPREAL1:def 8; hence contradiction by A51,A74,A76,TARSKI:def 1; suppose inw+1+1 < j; hence contradiction by A75,TOPREAL1:def 9; end; then inw+1 >= j by A3,A4,A7,A17,A46,A49,A64,A67,A69,A71,A72,JORDAN5C:28; then inw+1 >= inw+1+1 by A73,AXIOMS:22; hence contradiction by REAL_1:69; end; theorem for f being rectangular special_circular_sequence, g being S-Sequence_in_R2 st g/.1 in LeftComp f & g/.len g in RightComp f holds Last_Point(L~g,g/.1,g/.len g,L~f) <> SE-corner L~f proof let f be rectangular special_circular_sequence, g be S-Sequence_in_R2 such that A1: g/.1 in LeftComp f and A2: g/.len g in RightComp f; A3: L~f meets L~g by A1,A2,Th50; A4: L~f is closed by SPPOL_1:49; L~f is closed & L~g is closed by SPPOL_1:49; then A5: L~f /\ L~g is closed by TOPS_1:35; A6: L~g is_an_arc_of g/.1, g/.len g by TOPREAL1:31; set se = SE-corner L~f, ise = Index(se,g); assume A7: Last_Point(L~g,g/.1,g/.len g,L~f) = SE-corner L~f; then A8: se in L~g /\ L~f by A3,A5,A6,JORDAN5C:def 2; then A9: se in L~g by XBOOLE_0:def 3; A10: L~f misses RightComp f by Th42; A11: se in L~f by A8,XBOOLE_0:def 3; A12: len g in dom g by FINSEQ_5:6; then g.len g = g/.len g by FINSEQ_4:def 4; then A13: se <> g.len g by A2,A10,A11,XBOOLE_0:3; A14: ise < len g by A9,JORDAN3:41; then A15: 1 <= ise & ise+1 <= len g by A9,JORDAN3:41,NAT_1:38; A16: se in LSeg(g,ise) by A9,JORDAN3:42; A17: 1 <= ise+1 by NAT_1:29; then A18: ise+1 in dom g by A15,FINSEQ_3:27; A19: now assume se <> g.(ise+1); then A20: se <> g/.(ise+1) by A18,FINSEQ_4:def 4; A21: len g >= 1 by A15,A17,AXIOMS:22; per cases; suppose A22: g/.(ise+1) in L~f; then ise+1 <> len g by A2,A10,XBOOLE_0:3; then ise+1 < len g by A15,AXIOMS:21; then A23: ise+1+1 <= len g by NAT_1:38; then g/.(ise+1) in LSeg(g,ise+1) by A17,TOPREAL1:27; then ise >= ise+1 by A3,A4,A7,A15,A16,A17,A20,A22,A23,JORDAN5C:28; hence contradiction by REAL_1:69; suppose not g/.(ise+1) in L~f; then g/.(ise+1) in (L~f)` by SUBSET_1:50; then A24: g/.(ise+1) in LeftComp f \/ RightComp f by GOBRD12:11; A25: now A26: RightComp f = {q : W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f} by Th54; assume g/.(ise+1) in RightComp f; then A27: ex q st g/.(ise+1) = q & W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f by A26; A28: LSeg(g,ise) = LSeg(g/.ise,g/.(ise+1)) by A15,TOPREAL1:def 5; LSeg(g,ise) is vertical or LSeg(g,ise) is horizontal by SPPOL_1:41; then (g/.(ise+1))`1 = se`1 or (g/.(ise+1))`2 = se`2 by A16,A28,Th19,Th20; hence contradiction by A27,PSCOMP_1:78,79; end; then A29: g/.(ise+1) in LeftComp f by A24,XBOOLE_0:def 2; A30: ise+1<len g by A2,A15,A25,AXIOMS:21; reconsider m = mid(g,ise+1,len g) as S-Sequence_in_R2 by A2,A15,A17,A21,A25,JORDAN3:39; A31: m/.1 in LeftComp f by A12,A18,A29,SPRECT_2:12; m/.len m in RightComp f by A2,A12,A18,SPRECT_2:13; then L~f meets L~m by A31,Th50; then consider q being set such that A32: q in L~f and A33: q in L~m by XBOOLE_0:3; reconsider q as Point of TOP-REAL 2 by A33; consider i such that A34: 1 <= i & i+1 <= len m and A35: q in LSeg(m,i) by A33,SPPOL_2:13; A36: len m = len g-'(ise+1)+1 by A15,A17,JORDAN4:20; i < len m by A34,NAT_1:38; then A37: LSeg(m,i)=LSeg(g,i+(ise+1)-'1) by A17,A30,A34,A36,JORDAN4:31; set j = i+(ise+1)-'1; A38: j = i+ise+1-'1 by XCMPLX_1:1 .= i+ise by BINARITH:39; ise >= 0 by NAT_1:18; then A39: 0+1 <= j by A34,A38,REAL_1:55; len m = len g -' ise by A14,A36,NAT_2:9; then len m + ise = len g by A14,AMI_5:4; then i+1 + ise <= len g by A34,AXIOMS:24; then A40: j + 1 <= len g by A38,XCMPLX_1:1; A41: j >= ise+1 by A34,A38,AXIOMS:24; now assume se = q; then A42: se in LSeg(g,ise) /\ LSeg(g,j) by A16,A35,A37,XBOOLE_0:def 3; then A43: LSeg(g,ise) meets LSeg(g,j) by XBOOLE_0:4; per cases by A41,AXIOMS:21; suppose A44: ise+1 = j; ise+1+1 <= len g by A30,NAT_1:38; then ise + (1+1) <= len g by XCMPLX_1:1; then LSeg(g,ise) /\ LSeg(g,ise+1) = {g/.(ise+1)} by A15,TOPREAL1:def 8; hence contradiction by A20,A42,A44,TARSKI:def 1; suppose ise+1 < j; hence contradiction by A43,TOPREAL1:def 9; end; then ise >= j by A3,A4,A7,A15,A16,A32,A35,A37,A39,A40,JORDAN5C:28; then ise >= ise+1 by A41,AXIOMS:22; hence contradiction by REAL_1:69; end; then A45: ise+1 < len g by A13,A15,AXIOMS:21; then A46: ise+1+1 <= len g by NAT_1:38; A47: 1 <= ise+1+1 by NAT_1:29; then A48: ise+1+1 in dom g by A46,FINSEQ_3:27; g/.(ise+1) in LSeg(g,ise+1) by A17,A46,TOPREAL1:27; then A49: se in LSeg(g,ise+1) by A18,A19,FINSEQ_4:def 4; ise+1 < ise+1+1 by NAT_1:38; then A50: se <> g.(ise+1+1) by A18,A19,A48,FUNCT_1:def 8; then A51: se <> g/.(ise+1+1) by A48,FINSEQ_4:def 4; A52: len g >= 1 by A46,A47,AXIOMS:22; per cases; suppose A53: g/.(ise+1+1) in L~f; then ise+1+1 <> len g by A2,A10,XBOOLE_0:3; then ise+1+1 < len g by A46,AXIOMS:21; then A54: ise+1+1+1 <= len g by NAT_1:38; then A55: g/.(ise+1+1) in LSeg(g,ise+1+1) by A47,TOPREAL1:27; se <> g/.(ise+1+1) by A48,A50,FINSEQ_4:def 4; then ise+1 >= ise+1+1 by A3,A4,A7,A17,A46,A47,A49,A53,A54,A55,JORDAN5C:28; hence contradiction by REAL_1:69; suppose not g/.(ise+1+1) in L~f; then g/.(ise+1+1) in (L~f)` by SUBSET_1:50; then A56: g/.(ise+1+1) in LeftComp f \/ RightComp f by GOBRD12:11; A57: now A58: RightComp f = {q : W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f} by Th54; assume g/.(ise+1+1) in RightComp f; then A59: ex q st g/.(ise+1+1) = q & W-bound L~f < q`1 & q`1 < E-bound L~f & S-bound L~f < q`2 & q`2 < N-bound L~f by A58; A60: LSeg(g,ise+1) = LSeg(g/.(ise+1),g/.(ise+1+1)) by A17,A46,TOPREAL1:def 5; LSeg(g,ise+1) is vertical or LSeg(g,ise+1) is horizontal by SPPOL_1:41; then (g/.(ise+1+1))`1 = se`1 or (g/.(ise+1+1))`2 = se`2 by A49,A60,Th19,Th20; hence contradiction by A59,PSCOMP_1:78,79; end; then A61: g/.(ise+1+1) in LeftComp f by A56,XBOOLE_0:def 2; A62: ise+1+1<len g by A2,A46,A57,AXIOMS:21; reconsider m = mid(g,ise+1+1,len g) as S-Sequence_in_R2 by A2,A46,A47,A52,A57,JORDAN3:39; A63: m/.1 in LeftComp f by A12,A48,A61,SPRECT_2:12; m/.len m in RightComp f by A2,A12,A48,SPRECT_2:13; then L~f meets L~m by A63,Th50; then consider q being set such that A64: q in L~f and A65: q in L~m by XBOOLE_0:3; reconsider q as Point of TOP-REAL 2 by A65; consider i such that A66: 1 <= i & i+1 <= len m and A67: q in LSeg(m,i) by A65,SPPOL_2:13; A68: len m = len g-'(ise+1+1)+1 by A46,A47,JORDAN4:20; i < len m by A66,NAT_1:38; then A69: LSeg(m,i)=LSeg(g,i+(ise+1+1)-'1) by A47,A62,A66,A68,JORDAN4:31; set j = i+(ise+1+1)-'1; A70: j = i+(ise+1)+1-'1 by XCMPLX_1:1 .= i+ise+1+1-'1 by XCMPLX_1:1 .= i+ise+1 by BINARITH:39; then A71: 0+1 <= j by NAT_1:29; len m = len g -' (ise+1) by A45,A68,NAT_2:9; then len m + (ise+1) = len g by A15,AMI_5:4; then i+ 1 + (ise +1) <= len g by A66,AXIOMS:24; then i+ 1 + ise +1 <= len g by XCMPLX_1:1; then A72: j + 1 <= len g by A70,XCMPLX_1:1; j = i+(ise+1) by A70,XCMPLX_1:1; then A73: j >= ise+1+1 by A66,AXIOMS:24; now assume se = q; then A74: se in LSeg(g,ise+1) /\ LSeg(g,j) by A49,A67,A69,XBOOLE_0:def 3; then A75: LSeg(g,ise+1) meets LSeg(g,j) by XBOOLE_0:4; per cases by A73,AXIOMS:21; suppose A76: ise+1+1 = j; ise+1+1+1 <= len g by A62,NAT_1:38; then ise+1 + (1+1) <= len g by XCMPLX_1:1; then LSeg(g,ise+1) /\ LSeg(g,ise+1+1) = {g/.(ise+1+1)} by A17,TOPREAL1:def 8; hence contradiction by A51,A74,A76,TARSKI:def 1; suppose ise+1+1 < j; hence contradiction by A75,TOPREAL1:def 9; end; then ise+1 >= j by A3,A4,A7,A17,A46,A49,A64,A67,A69,A71,A72,JORDAN5C:28; then ise+1 >= ise+1+1 by A73,AXIOMS:22; hence contradiction by REAL_1:69; end; theorem Th57: for f being rectangular special_circular_sequence, p being Point of TOP-REAL 2 st W-bound L~f > p`1 or p`1 > E-bound L~f or S-bound L~f > p`2 or p`2 > N-bound L~f holds p in LeftComp f proof let f be rectangular special_circular_sequence, p be Point of TOP-REAL 2; LeftComp f = {q : not(W-bound L~f <= q`1 & q`1 <= E-bound L~f & S-bound L~f <= q`2 & q`2 <= N-bound L~f)} by Th54; hence thesis; end; theorem for f being clockwise_oriented (non constant standard special_circular_sequence) st f/.1 = N-min L~f holds LeftComp SpStSeq L~f c= LeftComp f proof let f be clockwise_oriented (non constant standard special_circular_sequence) such that A1: f/.1 = N-min L~f; A2: LeftComp f is_a_component_of (L~f)` by GOBOARD9:def 1; LeftComp SpStSeq L~f is_a_component_of (L~SpStSeq L~f)` by GOBOARD9:def 1; then consider B1 being Subset of (TOP-REAL 2)|(L~SpStSeq L~f)` such that A3: B1 = LeftComp SpStSeq L~f and A4: B1 is_a_component_of (TOP-REAL 2)|(L~SpStSeq L~f)` by CONNSP_1:def 6; B1 is connected by A4,CONNSP_1:def 5; then A5: LeftComp SpStSeq L~f is connected by A3,CONNSP_1:24; consider i such that A6: 1 <= i & i < len GoB f and A7: N-min L~f = (GoB f)*(i,width GoB f) by Th45; A8: i in dom GoB f by A6,FINSEQ_3:27; then A9: f/.2 = (GoB f)*(i+1,width GoB f) by A1,A7,Th46; A10: width GoB f >= 1 by GOBRD11:34; then A11: width GoB f -' 1 + 1 = width GoB f by AMI_5:4; len f > 4 by GOBOARD7:36; then A12: 1+1 <= len f by AXIOMS:22; A13: [i,width GoB f] in Indices GoB f by A6,A10,GOBOARD7:10; A14: 1 <= i+1 & i+1 <= len GoB f by A6,NAT_1:38; then [i+1,width GoB f] in Indices GoB f by A10,GOBOARD7:10; then A15: left_cell(f,1) = cell(GoB f,i,width GoB f) by A1,A7,A9,A11,A12,A13, GOBOARD5:29; set a = 1/2*((GoB f)*(i,width GoB f)+(GoB f)*(i+1,width GoB f))+|[0,1]|, q = 1/2*((GoB f)*(i,width GoB f)+(GoB f)*(i+1,width GoB f)); A16: a in Int cell(GoB f,i,width GoB f) by A6,A14,GOBOARD6:35; A17: Int cell(GoB f,i,width GoB f) c= LeftComp f by A15,GOBOARD9:def 1; A18: a`2 = q`2+|[0,1]|`2 by TOPREAL3:7 .= q`2+1 by EUCLID:56; A19: N-bound L~SpStSeq L~f = N-bound L~f by SPRECT_1:68; A20: (f/.2)`2 = ((GoB f)*(1,width GoB f))`2 by A9,A10,A14,GOBOARD5:2 .= (N-min L~f)`2 by A6,A7,A10,GOBOARD5:2 .= N-bound L~f by PSCOMP_1:94; A21: LeftComp SpStSeq L~f = {p : not(W-bound L~SpStSeq L~f <= p`1 & p`1 <= E-bound L~SpStSeq L~f & S-bound L~SpStSeq L~f <= p`2 & p`2 <= N-bound L~SpStSeq L~f)} by Th54; q`2 = (1/2*((GoB f)*(i,width GoB f)+f/.2))`2 by A1,A7,A8,Th46 .= 1/2*(f/.1+f/.2)`2 by A1,A7,TOPREAL3:9 .= 1/2*((f/.1)`2+(f/.2)`2) by TOPREAL3:7 .= 1/2*(N-bound L~f+N-bound L~f) by A1,A20,PSCOMP_1:94 .= 1/2*(2*N-bound L~f) by XCMPLX_1:11 .= N-bound L~f by XCMPLX_1:108; then a`2 > 0 + N-bound L~f by A18,REAL_1:67; then a`2 > N-bound L~SpStSeq L~f by SPRECT_1:68; then a in LeftComp SpStSeq L~f by A21; then A22: LeftComp f meets LeftComp SpStSeq L~f by A16,A17,XBOOLE_0:3; defpred X[Element of TOP-REAL 2] means $1`2 < S-bound L~f; reconsider P1 = { p: X[p] } as Subset of TOP-REAL 2 from SubsetD; defpred X[Element of TOP-REAL 2] means $1`2 > N-bound L~f; reconsider P2 = { p: X[p] } as Subset of TOP-REAL 2 from SubsetD; defpred X[Element of TOP-REAL 2] means $1`1 > E-bound L~f; reconsider P3 = { p: X[p] } as Subset of TOP-REAL 2 from SubsetD; defpred X[Element of TOP-REAL 2] means $1`1 < W-bound L~f; reconsider P4 = { p: X[p] } as Subset of TOP-REAL 2 from SubsetD; A23: W-bound L~SpStSeq L~f = W-bound L~f by SPRECT_1:66; A24: S-bound L~SpStSeq L~f = S-bound L~f by SPRECT_1:67; A25: E-bound L~SpStSeq L~f = E-bound L~f by SPRECT_1:69; A26: LeftComp SpStSeq L~f = P1 \/ P2 \/ (P3 \/ P4) proof thus LeftComp SpStSeq L~f c= P1 \/ P2 \/ (P3 \/ P4) proof let x be set; assume x in LeftComp SpStSeq L~f; then x in { p : not(W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f)} by A19,A23,A24,A25,Th54; then ex p st p = x & not(W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f); then x in P1 or x in P2 or x in P3 or x in P4; then x in P1 \/ P2 or x in P3 \/ P4 by XBOOLE_0:def 2; hence thesis by XBOOLE_0:def 2; end; let x be set; assume x in P1 \/ P2 \/ (P3 \/ P4); then A27: x in P1 \/ P2 or x in P3 \/ P4 by XBOOLE_0:def 2; per cases by A27,XBOOLE_0:def 2; suppose x in P1; then ex p st x = p & p`2 < S-bound L~f; hence x in LeftComp SpStSeq L~f by A24,Th57; suppose x in P2; then ex p st x = p & p`2 > N-bound L~f; hence x in LeftComp SpStSeq L~f by A19,Th57; suppose x in P3; then ex p st x = p & p`1 > E-bound L~f; hence x in LeftComp SpStSeq L~f by A25,Th57; suppose x in P4; then ex p st x = p & p`1 < W-bound L~f; hence x in LeftComp SpStSeq L~f by A23,Th57; end; for p st p in P1 holds p`2 < (GoB f)*(1,1)`2 proof let p; assume p in P1; then ex q st p = q & q`2 < S-bound L~f; hence p`2 < (GoB f)*(1,1)`2 by JORDAN5D:40; end; then A28: P1 misses L~f by GOBOARD8:23; for p st p in P2 holds p`2 > (GoB f)*(1, width GoB f)`2 proof let p; assume p in P2; then ex q st p = q & q`2 > N-bound L~f; hence p`2 > (GoB f)*(1,width GoB f)`2 by JORDAN5D:42; end; then P2 misses L~f by GOBOARD8:24; then A29: P1 \/ P2 misses L~f by A28,XBOOLE_1:70; for p st p in P3 holds p`1 > (GoB f)*(len GoB f,1)`1 proof let p; assume p in P3; then ex q st p = q & q`1 > E-bound L~f; hence p`1 > (GoB f)*(len GoB f,1)`1 by JORDAN5D:41; end; then A30: P3 misses L~f by GOBOARD8:22; for p st p in P4 holds p`1 < (GoB f)*(1,1)`1 proof let p; assume p in P4; then ex q st p = q & q`1 < W-bound L~f; hence p`1 < (GoB f)*(1,1)`1 by JORDAN5D:39; end; then P4 misses L~f by GOBOARD8:21; then P3 \/ P4 misses L~f by A30,XBOOLE_1:70; then LeftComp SpStSeq L~f misses L~f by A26,A29,XBOOLE_1:70; then LeftComp SpStSeq L~f c= (L~f)` by SUBSET_1:43; hence LeftComp SpStSeq L~f c= LeftComp f by A2,A5,A22,GOBOARD9:6; end; begin :: In the area theorem Th59: for f being FinSequence of TOP-REAL 2, p,q being Point of TOP-REAL 2 holds <*p,q*> is_in_the_area_of f iff <*p*> is_in_the_area_of f & <*q*> is_in_the_area_of f proof let f be FinSequence of TOP-REAL 2, p,q be Point of TOP-REAL 2; thus <*p,q*> is_in_the_area_of f implies <*p*> is_in_the_area_of f & <*q*> is_in_the_area_of f proof assume A1: <*p,q*> is_in_the_area_of f; dom<*p,q*> = {1,2} by FINSEQ_1:4,FINSEQ_3:29; then 1 in dom<*p,q*> & <*p,q*>/.1 = p & 2 in dom<*p,q*> & <*p,q*>/.2 = q by FINSEQ_4:26,TARSKI:def 2; then A2: W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f & W-bound L~f <= q`1 & q`1 <= E-bound L~f & S-bound L~f <= q`2 & q`2 <= N-bound L~f by A1,SPRECT_2:def 1; thus <*p*> is_in_the_area_of f proof let i; assume i in dom<*p*>; then i in {1} by FINSEQ_1:4,55; then i = 1 by TARSKI:def 1; hence thesis by A2,FINSEQ_4:25; end; let i; assume i in dom<*q*>; then i in {1} by FINSEQ_1:4,55; then i = 1 by TARSKI:def 1; hence thesis by A2,FINSEQ_4:25; end; assume A3: <*p*> is_in_the_area_of f; dom<*p*> = {1} by FINSEQ_1:4,55; then 1 in dom<*p*> & <*p*>/.1 = p by FINSEQ_4:25,TARSKI:def 1; then A4: W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f by A3,SPRECT_2:def 1; assume A5: <*q*> is_in_the_area_of f; dom<*q*> = {1} by FINSEQ_1:4,55; then 1 in dom<*q*> & <*q*>/.1 = q by FINSEQ_4:25,TARSKI:def 1; then A6: W-bound L~f <= q`1 & q`1 <= E-bound L~f & S-bound L~f <= q`2 & q`2 <= N-bound L~f by A5,SPRECT_2:def 1; let i; assume i in dom<*p,q*>; then i in {1,2} by FINSEQ_1:4,FINSEQ_3:29; then i =1 or i =2 by TARSKI:def 2; hence thesis by A4,A6,FINSEQ_4:26; end; theorem Th60: for f being rectangular FinSequence of TOP-REAL 2, p being Point of TOP-REAL 2 st <*p*> is_in_the_area_of f & (p`1 = W-bound L~f or p`1 = E-bound L~f or p`2 = S-bound L~f or p`2 = N-bound L~f) holds p in L~f proof let f be rectangular FinSequence of TOP-REAL 2, p be Point of TOP-REAL 2; assume A1: <*p*> is_in_the_area_of f; dom<*p*> = {1} by FINSEQ_1:4,55; then 1 in dom<*p*> & <*p*>/.1 = p by FINSEQ_4:25,TARSKI:def 1; then A2: W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f by A1,SPRECT_2:def 1; consider D being non vertical non horizontal non empty compact Subset of TOP-REAL 2 such that A3: f = SpStSeq D by SPRECT_1:def 2; A4: L~f = (LSeg(NW-corner D,NE-corner D) \/ LSeg(NE-corner D,SE-corner D)) \/ (LSeg(SE-corner D,SW-corner D) \/ LSeg(SW-corner D,NW-corner D)) by A3,SPRECT_1:43; A5: W-bound L~SpStSeq D = W-bound D by SPRECT_1:66; A6: S-bound L~SpStSeq D = S-bound D by SPRECT_1:67; A7: N-bound L~SpStSeq D = N-bound D by SPRECT_1:68; A8: E-bound L~SpStSeq D = E-bound D by SPRECT_1:69; assume A9: p`1 = W-bound L~f or p`1 = E-bound L~f or p`2 = S-bound L~f or p`2 = N-bound L~f; per cases by A9; suppose A10: p`1 = W-bound L~f; A11: (SW-corner D)`1 = W-bound D & (NW-corner D)`1 = W-bound D by PSCOMP_1:72,74; (SW-corner D)`2 = S-bound D & (NW-corner D)`2 = N-bound D by PSCOMP_1:73,75; then p in LSeg(SW-corner D,NW-corner D) by A2,A3,A5,A6,A7,A10,A11,GOBOARD7:8; then p in LSeg(SE-corner D,SW-corner D) \/ LSeg(SW-corner D,NW-corner D) by XBOOLE_0:def 2; hence p in L~f by A4,XBOOLE_0:def 2; suppose A12: p`1 = E-bound L~f; A13: (NE-corner D)`1 = E-bound D & (SE-corner D)`1 = E-bound D by PSCOMP_1:76,78; (NE-corner D)`2 = N-bound D & (SE-corner D)`2 = S-bound D by PSCOMP_1:77,79; then p in LSeg(NE-corner D,SE-corner D) by A2,A3,A6,A7,A8,A12,A13,GOBOARD7:8; then p in LSeg(NW-corner D,NE-corner D) \/ LSeg(NE-corner D,SE-corner D) by XBOOLE_0:def 2; hence p in L~f by A4,XBOOLE_0:def 2; suppose A14: p`2 = S-bound L~f; A15: (SE-corner D)`1 = E-bound D & (SW-corner D)`1 = W-bound D by PSCOMP_1:72,78; (SE-corner D)`2 = S-bound D & (SW-corner D)`2 = S-bound D by PSCOMP_1:73,79; then p in LSeg(SE-corner D,SW-corner D) by A2,A3,A5,A6,A8,A14,A15,GOBOARD7:9; then p in LSeg(SE-corner D,SW-corner D) \/ LSeg(SW-corner D,NW-corner D) by XBOOLE_0:def 2; hence p in L~f by A4,XBOOLE_0:def 2; suppose A16: p`2 = N-bound L~f; A17: (NW-corner D)`1 = W-bound D & (NE-corner D)`1 = E-bound D by PSCOMP_1:74,76; (NW-corner D)`2 = N-bound D & (NE-corner D)`2 = N-bound D by PSCOMP_1:75,77; then p in LSeg(NW-corner D,NE-corner D) by A2,A3,A5,A7,A8,A16,A17,GOBOARD7:9; then p in LSeg(NW-corner D,NE-corner D) \/ LSeg(NE-corner D,SE-corner D) by XBOOLE_0:def 2; hence p in L~f by A4,XBOOLE_0:def 2; end; theorem Th61: for f being FinSequence of TOP-REAL 2, p,q being Point of TOP-REAL 2, r being Real st 0<=r & r <= 1 & <*p,q*> is_in_the_area_of f holds <*(1-r)*p+r*q*> is_in_the_area_of f proof let f be FinSequence of TOP-REAL 2, p,q be Point of TOP-REAL 2, r be Real such that A1: 0 <= r and A2: r <= 1 and A3: <*p,q*> is_in_the_area_of f; dom<*p,q*> = {1,2} by FINSEQ_1:4,FINSEQ_3:29; then 1 in dom<*p,q*> & <*p,q*>/.1 = p & 2 in dom<*p,q*> & <*p,q*>/.2 = q by FINSEQ_4:26,TARSKI:def 2; then A4: W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f & W-bound L~f <= q`1 & q`1 <= E-bound L~f & S-bound L~f <= q`2 & q`2 <= N-bound L~f by A3,SPRECT_2:def 1; let n; assume A5: n in dom <*(1-r)*p+r*q*>; dom <*(1-r)*p+r*q*> = {1} by FINSEQ_1:4,55; then A6: n = 1 by A5,TARSKI:def 1; A7: ((1-r)*p+r*q)`1 = ((1-r)*p)`1+(r*q)`1 by TOPREAL3:7 .= (1-r)*p`1+(r*q)`1 by TOPREAL3:9 .= (1-r)*p`1+r*q`1 by TOPREAL3:9; A8: (1-r)*W-bound L~f+r*W-bound L~f = ((1-r)+r)*W-bound L~f by XCMPLX_1:8 .= 1*W-bound L~f by XCMPLX_1:27; A9: r*W-bound L~f <= r*q`1 by A1,A4,AXIOMS:25; A10: 1-r >= 0 by A2,SQUARE_1:12; then (1-r)*W-bound L~f <= (1-r)*p`1 by A4,AXIOMS:25; then W-bound L~f <= (1-r)*p`1+r*q`1 by A8,A9,REAL_1:55; hence W-bound L~f <= (<*(1-r)*p+r*q*>/.n)`1 by A6,A7,FINSEQ_4:25; A11: (1-r)*E-bound L~f+r*E-bound L~f = ((1-r)+r)*E-bound L~f by XCMPLX_1:8 .= 1*E-bound L~f by XCMPLX_1:27; A12: r*q`1<= r*E-bound L~f by A1,A4,AXIOMS:25; (1-r)*p`1 <= (1-r)*E-bound L~f by A4,A10,AXIOMS:25; then (1-r)*p`1+r*q`1 <= E-bound L~f by A11,A12,REAL_1:55; hence (<*(1-r)*p+r*q*>/.n)`1 <= E-bound L~f by A6,A7,FINSEQ_4:25; A13: ((1-r)*p+r*q)`2 = ((1-r)*p)`2+(r*q)`2 by TOPREAL3:7 .= (1-r)*p`2+(r*q)`2 by TOPREAL3:9 .= (1-r)*p`2+r*q`2 by TOPREAL3:9; A14: (1-r)*S-bound L~f+r*S-bound L~f = ((1-r)+r)*S-bound L~f by XCMPLX_1:8 .= 1*S-bound L~f by XCMPLX_1:27; A15: r*S-bound L~f <= r*q`2 by A1,A4,AXIOMS:25; (1-r)*S-bound L~f <= (1-r)*p`2 by A4,A10,AXIOMS:25; then S-bound L~f <= (1-r)*p`2+r*q`2 by A14,A15,REAL_1:55; hence S-bound L~f <= (<*(1-r)*p+r*q*>/.n)`2 by A6,A13,FINSEQ_4:25; A16: (1-r)*N-bound L~f+r*N-bound L~f = ((1-r)+r)*N-bound L~f by XCMPLX_1:8 .= 1*N-bound L~f by XCMPLX_1:27; A17: r*q`2<= r*N-bound L~f by A1,A4,AXIOMS:25; (1-r)*p`2 <= (1-r)*N-bound L~f by A4,A10,AXIOMS:25; then (1-r)*p`2+r*q`2 <= N-bound L~f by A16,A17,REAL_1:55; hence (<*(1-r)*p+r*q*>/.n)`2 <= N-bound L~f by A6,A13,FINSEQ_4:25; end; theorem Th62: for f, g being FinSequence of TOP-REAL 2 st g is_in_the_area_of f & i in dom g holds <*g/.i*> is_in_the_area_of f proof let f, g be FinSequence of TOP-REAL 2 such that A1: g is_in_the_area_of f and A2: i in dom g; let n; assume A3: n in dom <*g/.i*>; dom <*g/.i*> = {1} by FINSEQ_1:4,55; then n = 1 by A3,TARSKI:def 1; then <*g/.i*>/.n = g/.i by FINSEQ_4:25; hence thesis by A1,A2,SPRECT_2:def 1; end; theorem Th63: for f, g being FinSequence of TOP-REAL 2, p being Point of TOP-REAL 2 st g is_in_the_area_of f & p in L~g holds <*p*> is_in_the_area_of f proof let f, g be FinSequence of TOP-REAL 2, p be Point of TOP-REAL 2 such that A1: g is_in_the_area_of f; assume p in L~g; then consider i such that A2: 1 <= i and A3: i+1 <= len g and A4: p in LSeg(g/.i,g/.(i+1)) by SPPOL_2:14; i <= i+1 by NAT_1:29; then i <= len g by A3,AXIOMS:22; then i in dom g by A2,FINSEQ_3:27; then A5: <*g/.i*> is_in_the_area_of f by A1,Th62; 1 <= i+1 by NAT_1:29; then i+1 in dom g by A3,FINSEQ_3:27; then <*g/.(i+1)*> is_in_the_area_of f by A1,Th62; then A6: <*g/.i,g/.(i+1)*> is_in_the_area_of f by A5,Th59; ex r being Real st 0<=r & r<=1 & p = (1-r)*g/.i+r*g/.(i+1) by A4,SPPOL_1:21; hence thesis by A6,Th61; end; theorem Th64: for f being rectangular FinSequence of TOP-REAL 2, p,q being Point of TOP-REAL 2 st not q in L~f & <*p,q*> is_in_the_area_of f holds LSeg(p,q) /\ L~f c= {p} proof let f be rectangular FinSequence of TOP-REAL 2, p,q be Point of TOP-REAL 2 such that A1: not q in L~f; assume A2: <*p,q*> is_in_the_area_of f; then <*q*> is_in_the_area_of f by Th59; then A3: q`1 <> W-bound L~f & q`1 <> E-bound L~f & q`2 <> S-bound L~f & q`2 <> N-bound L~f by A1,Th60; A4: dom <*p,q*> = {1,2} by FINSEQ_1:4,FINSEQ_3:29; then A5: 1 in dom <*p,q*> by TARSKI:def 2; A6: <*p,q*>/.1 = p by FINSEQ_4:26; then A7: W-bound L~f <= p`1 & p`1 <= E-bound L~f by A2,A5,SPRECT_2:def 1; A8: S-bound L~f <= p`2 & p`2 <= N-bound L~f by A2,A5,A6,SPRECT_2:def 1; A9: 2 in dom <*p,q*> by A4,TARSKI:def 2; A10: <*p,q*>/.2 = q by FINSEQ_4:26; then W-bound L~f <= q`1 & q`1 <= E-bound L~f by A2,A9,SPRECT_2:def 1; then A11: W-bound L~f < q`1 & q`1 < E-bound L~f by A3,REAL_1:def 5; S-bound L~f <= q`2 & q`2 <= N-bound L~f by A2,A9,A10,SPRECT_2:def 1; then A12: S-bound L~f < q`2 & q`2 < N-bound L~f by A3,REAL_1:def 5; let x be set; assume A13: x in LSeg(p,q) /\ L~f; then A14: x in LSeg(p,q) by XBOOLE_0:def 3; reconsider p' = x as Point of TOP-REAL 2 by A13; consider r being Real such that A15: 0<=r and A16: r<=1 and A17: p' = (1-r)*p+r*q by A14,SPPOL_1:21; A18: p'`1 = ((1-r)*p)`1+(r*q)`1 by A17,TOPREAL3:7 .= (1-r)*p`1+(r*q)`1 by TOPREAL3:9 .= (1-r)*p`1+r*q`1 by TOPREAL3:9; A19: p'`2 = ((1-r)*p)`2+(r*q)`2 by A17,TOPREAL3:7 .= (1-r)*p`2+(r*q)`2 by TOPREAL3:9 .= (1-r)*p`2+r*q`2 by TOPREAL3:9; A20: p' in L~f by A13,XBOOLE_0:def 3; per cases by A20,Th49; suppose p'`1 = W-bound L~f; then r = 0 by A7,A11,A15,A16,A18,Th4; then p' = 1*p+0.REAL 2 by A17,EUCLID:33 .= 1*p by EUCLID:31 .= p by EUCLID:33; hence x in {p} by ZFMISC_1:37; suppose p'`1 = E-bound L~f; then r = 0 by A7,A11,A15,A16,A18,Th3; then p' = 1*p+0.REAL 2 by A17,EUCLID:33 .= 1*p by EUCLID:31 .= p by EUCLID:33; hence x in {p} by ZFMISC_1:37; suppose p'`2 = S-bound L~f; then r = 0 by A8,A12,A15,A16,A19,Th4; then p' = 1*p+0.REAL 2 by A17,EUCLID:33 .= 1*p by EUCLID:31 .= p by EUCLID:33; hence x in {p} by ZFMISC_1:37; suppose p'`2 = N-bound L~f; then r = 0 by A8,A12,A15,A16,A19,Th3; then p' = 1*p+0.REAL 2 by A17,EUCLID:33 .= 1*p by EUCLID:31 .= p by EUCLID:33; hence x in {p} by ZFMISC_1:37; end; theorem for f being rectangular FinSequence of TOP-REAL 2, p,q being Point of TOP-REAL 2 st p in L~f & not q in L~f & <*q*> is_in_the_area_of f holds LSeg(p,q) /\ L~f = {p} proof let f be rectangular FinSequence of TOP-REAL 2, p,q be Point of TOP-REAL 2 such that A1: p in L~f and A2: not q in L~f and A3: <*q*> is_in_the_area_of f; f is_in_the_area_of f by SPRECT_2:25; then A4: <*p*> is_in_the_area_of f by A1,Th63; <*p,q*> = <*p*>^<*q*> by FINSEQ_1:def 9; then <*p,q*> is_in_the_area_of f by A3,A4,SPRECT_2:28; hence LSeg(p,q) /\ L~f c= {p} by A2,Th64; p in LSeg(p,q) by TOPREAL1:6; then p in LSeg(p,q) /\ L~f by A1,XBOOLE_0:def 3; hence {p} c= LSeg(p,q) /\ L~f by ZFMISC_1:37; end; theorem Th66: for f being non constant standard special_circular_sequence st 1 <= i & i <= len GoB f & 1 <= j & j <= width GoB f holds <*(GoB f)*(i,j)*> is_in_the_area_of f proof let f be non constant standard special_circular_sequence such that A1: 1 <= i & i <= len GoB f & 1 <= j & j <= width GoB f; set p = (GoB f)*(i,j); let n; assume n in dom<*(GoB f)*(i,j)*>; then n in {1} by FINSEQ_1:4,55; then n = 1 by TARSKI:def 1; then A2: <*p*>/.n = p by FINSEQ_4:25; set G = GoB f; A3: 1 <= len G by A1,AXIOMS:22; A4: 1 <= width G by A1,AXIOMS:22; A5: W-bound L~f = G*(1,1)`1 by JORDAN5D:39 .= G*(1,j)`1 by A1,A3,GOBOARD5:3; A6: i = 1 or i > 1 by A1,REAL_1:def 5; A7: S-bound L~f = (G)*(1,1)`2 by JORDAN5D:40 .= (G)*(i,1)`2 by A1,A4,GOBOARD5:2; A8: j = 1 or j > 1 by A1,REAL_1:def 5; A9: E-bound L~f = (G)*(len G,1)`1 by JORDAN5D:41 .= (G)*(len G,j)`1 by A1,A3,GOBOARD5:3; A10: i = len G or i < len G by A1,REAL_1:def 5; A11: N-bound L~f = (G)*(1,width G)`2 by JORDAN5D:42 .= (G)*(i,width G)`2 by A1,A4,GOBOARD5:2; j = width G or j < width G by A1,REAL_1:def 5; hence thesis by A2,A5,A6,A7,A8,A9,A10,A11,GOBOARD5:4,5; end; theorem for g being FinSequence of TOP-REAL 2, p,q being Point of TOP-REAL 2 st <*p,q*> is_in_the_area_of g holds <*1/2*(p+q)*> is_in_the_area_of g proof let g be FinSequence of TOP-REAL 2, p,q be Point of TOP-REAL 2; 1/2*(p+q) = (1 - 1/2)*p + 1/2*q by EUCLID:36; hence thesis by Th61; end; theorem for f, g being FinSequence of TOP-REAL 2 st g is_in_the_area_of f holds Rev g is_in_the_area_of f proof let f, g be FinSequence of TOP-REAL 2 such that A1: g is_in_the_area_of f; A2: Rev Rev g = g by FINSEQ_6:29; A3: len Rev g = len g by FINSEQ_5:def 3; let n such that A4: n in dom Rev g; set i = len g + 1 -' n; A5: n <= len g by A3,A4,FINSEQ_3:27; len g <= len g + 1 by NAT_1:29; then n <= len g + 1 by A5,AXIOMS:22; then n + i = len g + 1 by AMI_5:4; then A6: (Rev g)/.n = g/.i by A2,A3,A4,FINSEQ_5:69; A7: i = len g -' n + 1 by A5,JORDAN4:3; then A8: 1 <= i by NAT_1:29; A9: i = len g - n + 1 by A5,A7,SCMFSA_7:3 .= len g - (n-1) by XCMPLX_1:37; n >= 1 by A4,FINSEQ_3:27; then n-1 >= 0 by SQUARE_1:12; then i <= len g - 0 by A9,REAL_1:92; then i in dom g by A8,FINSEQ_3:27; hence W-bound L~f <= ((Rev g)/.n)`1 & ((Rev g)/.n)`1 <= E-bound L~f & S-bound L~f <= ((Rev g)/.n)`2 & ((Rev g)/.n)`2 <= N-bound L~f by A1,A6,SPRECT_2:def 1; end; theorem for f, g being FinSequence of TOP-REAL 2, p being Point of TOP-REAL 2 st g is_in_the_area_of f & <*p*> is_in_the_area_of f & g is_S-Seq & p in L~g holds R_Cut(g,p) is_in_the_area_of f proof let f, g be FinSequence of TOP-REAL 2, p be Point of TOP-REAL 2 such that A1: g is_in_the_area_of f and A2: <*p*> is_in_the_area_of f and A3: g is_S-Seq; 2 <= len g by A3,TOPREAL1:def 10; then A4: 1 <= len g by AXIOMS:22; then A5: 1 in dom g by FINSEQ_3:27; assume p in L~g; then 1<=Index(p,g) & Index(p,g) < len g by JORDAN3:41; then A6: Index(p,g) in dom g by FINSEQ_3:27; per cases; suppose p<>g.1; then A7: R_Cut(g,p) = mid(g,1,Index(p,g))^<*p*> by JORDAN3:def 5; mid(g,1,Index(p,g)) is_in_the_area_of f by A1,A5,A6,SPRECT_2:26; hence R_Cut(g,p) is_in_the_area_of f by A2,A7,SPRECT_2:28; suppose p=g.1; then R_Cut(g,p) = <*g.1*> by JORDAN3:def 5 .= <*g/.1*> by A5,FINSEQ_4:def 4 .= mid(g,1,1) by A4,JORDAN4:27; hence R_Cut(g,p) is_in_the_area_of f by A1,A5,SPRECT_2:26; end; theorem for f being non constant standard special_circular_sequence, g being FinSequence of TOP-REAL2 holds g is_in_the_area_of f iff g is_in_the_area_of SpStSeq L~f proof let f be non constant standard special_circular_sequence, g be FinSequence of TOP-REAL2; A1: W-bound L~SpStSeq L~f = W-bound L~f & S-bound L~SpStSeq L~f = S-bound L~f & N-bound L~SpStSeq L~f = N-bound L~f & E-bound L~SpStSeq L~f = E-bound L~f by SPRECT_1:66,67,68,69; thus g is_in_the_area_of f implies g is_in_the_area_of SpStSeq L~f proof assume A2: g is_in_the_area_of f; let n; thus thesis by A1,A2,SPRECT_2:def 1; end; assume A3: g is_in_the_area_of SpStSeq L~f; let n; thus thesis by A1,A3,SPRECT_2:def 1; end; theorem for f being rectangular special_circular_sequence, g being S-Sequence_in_R2 st g/.1 in LeftComp f & g/.len g in RightComp f holds L_Cut(g,Last_Point(L~g,g/.1,g/.len g,L~f)) is_in_the_area_of f proof let f be rectangular special_circular_sequence, g be S-Sequence_in_R2 such that A1: g/.1 in LeftComp f and A2: g/.len g in RightComp f; set lp = Last_Point(L~g,g/.1,g/.len g,L~f), ilp = Index(lp,g), h = L_Cut(g,lp); A3: L~f misses LeftComp f by Th43; A4: L~g meets L~f by A1,A2,Th50; A5: L~g is closed & L~f is closed by SPPOL_1:49; then A6: L~g /\ L~f is closed by TOPS_1:35; L~g is_an_arc_of g/.1,g/.len g by TOPREAL1:31; then A7: lp in L~g /\ L~f by A4,A6,JORDAN5C:def 2; then A8: lp in L~f by XBOOLE_0:def 3; A9: lp in L~g by A7,XBOOLE_0:def 3; A10: len g in dom g by FINSEQ_5:6; 1 in dom g by FINSEQ_5:6; then A11: len g >= 1 by FINSEQ_3:27; A12: lp in LSeg(g,ilp) by A9,JORDAN3:42; given n such that A13: n in dom h and A14: W-bound L~f > (h/.n)`1 or (h/.n)`1 > E-bound L~f or S-bound L~f > (h/.n)`2 or (h/.n)`2 > N-bound L~f; LeftComp f = {p : not(W-bound L~f <= p`1 & p`1 <= E-bound L~f & S-bound L~f <= p`2 & p`2 <= N-bound L~f)} by Th54; then A15: h/.n in LeftComp f by A14; A16: 1 <= n & n <= len h by A13,FINSEQ_3:27; then A17: n = n -'1 +1 by AMI_5:4; A18: len<*lp*> = 1 by FINSEQ_1:56; A19: ilp < len g by A9,JORDAN3:41; then A20: ilp+1<=len g by NAT_1:38; A21: 1<=ilp+1 by NAT_1:29; then A22: len mid(g,ilp+1,len g)=len g-'(ilp+1)+1 by A20,JORDAN4:20 .= len g -' ilp by A19,NAT_2:9; then A23: ilp + len mid(g,ilp+1,len g) + 1 = len g + 1 by A19,AMI_5:4; A24: ilp+1 in dom g by A20,A21,FINSEQ_3:27; A25: n+ilp <= len h + ilp by A16,AXIOMS:24; A26: LeftComp f misses RightComp f by SPRECT_1:96; A27: 1 <= ilp by A9,JORDAN3:41; now assume A28: n = 1; per cases; suppose lp <> g.(ilp+1); then h = <*lp*>^mid(g,ilp+1,len g) by JORDAN3:def 4; then h/.n = lp by A28,FINSEQ_5:16; hence contradiction by A3,A8,A15,XBOOLE_0:3; suppose A29: lp = g.(ilp+1); then h = mid(g,ilp+1,len g) by JORDAN3:def 4; then h/.n = g/.(1+(ilp+1)-'1) by A10,A13,A20,A24,A28,SPRECT_2:7 .= g/.(ilp+1) by BINARITH:39 .= lp by A24,A29,FINSEQ_4:def 4; hence contradiction by A3,A8,A15,XBOOLE_0:3; end; then A30: n > 1 by A16,AXIOMS:21; then A31: 1+1 < ilp+n by A27,REAL_1:67; then A32: 1 <= ilp+n-'1 by JORDAN3:12; A33: ilp+n-'1 = ilp+(n-'1) by A16,JORDAN4:3; A34: 1 <= n-'1 by A17,A30,NAT_1:38; now assume A35: lp <> g.(ilp+1); then A36: h = <*lp*>^mid(g,ilp+1,len g) by JORDAN3:def 4; then A37: len h = 1 + len mid(g,ilp+1,len g) by A18,FINSEQ_1:35; then len h -' 1 = len mid(g,ilp+1,len g) by BINARITH:39; then A38: n-'1 <= len mid(g,ilp+1,len g) by A16,JORDAN3:5; then A39: h/.n = (mid(g,ilp+1,len g))/.(n-'1) by A17,A18,A34,A36,GOBOARD2:5; A40: ilp + len h = len g + 1 by A23,A37,XCMPLX_1:1; n-'1 in dom mid(g,ilp+1,len g) by A34,A38,FINSEQ_3:27; then A41: h/.n = g/.(n-'1+(ilp+1)-'1) by A10,A20,A24,A39,SPRECT_2:7 .= g/.(n+ilp-'1) by A17,XCMPLX_1:1; A42: ilp+n-'1 <= len g by A25,A40,Th6; A43: ilp+n-'1<>len g by A2,A15,A26,A41,XBOOLE_0:3; then reconsider m = mid(g,ilp+n-'1,len g) as S-Sequence_in_R2 by A11,A32,A42,JORDAN3:39; A44: ilp+n-'1 in dom g by A32,A42,FINSEQ_3:27; then A45: m/.1 in LeftComp f by A10,A15,A41,SPRECT_2:12; m/.len m in RightComp f by A2,A10,A44,SPRECT_2:13; then L~f meets L~m by A45,Th50; then consider q being set such that A46: q in L~f and A47: q in L~m by XBOOLE_0:3; reconsider q as Point of TOP-REAL 2 by A47; consider i such that A48: 1 <= i & i+1 <= len m and A49: q in LSeg(m,i) by A47,SPPOL_2:13; A50: len m = len g-'(ilp+n-'1)+1 by A32,A42,JORDAN4:20; A51: i < len m by A48,NAT_1:38; ilp+n-'1<len g by A42,A43,AXIOMS:21; then A52: LSeg(m,i)=LSeg(g,i+(ilp+n-'1)-'1) by A32,A48,A50,A51,JORDAN4:31; set j = i+(ilp+n-'1)-'1; j = i-'1+(ilp+n-'1) by A48,JORDAN4:3; then A53: j >= ilp+n-'1 by NAT_1:29; ilp+1 <= ilp+n-'1 by A33,A34,AXIOMS:24; then A54: ilp +1 <= j by A53,AXIOMS:22; A55: lp <> g/.(ilp+1) by A24,A35,FINSEQ_4:def 4; A56: 1 <= j by A21,A54,AXIOMS:22; i <= len g-'(ilp+n-'1) by A48,A50,REAL_1:53; then A57: i+(ilp+n-'1) <= len g by A42,Th7; i <= i+(ilp+n-'1) by NAT_1:29; then 1 <= i+(ilp+n-'1) by A48,AXIOMS:22; then A58: j + 1 <= len g by A57,AMI_5:4; now assume lp = q; then A59: lp in LSeg(g,ilp) /\ LSeg(g,j) by A12,A49,A52,XBOOLE_0:def 3; then A60: LSeg(g,ilp) meets LSeg(g,j) by XBOOLE_0:4; per cases by A54,AXIOMS:21; suppose A61: ilp+1 = j; then ilp + (1+1) <= len g by A58,XCMPLX_1:1; then LSeg(g,ilp) /\ LSeg(g,ilp+1) = {g/.(ilp+1)} by A27,TOPREAL1:def 8; hence contradiction by A55,A59,A61,TARSKI:def 1; suppose ilp+1 < j; hence contradiction by A60,TOPREAL1:def 9; end; then ilp >= j by A4,A5,A12,A20,A27,A46,A49,A52,A56,A58,JORDAN5C:28; then ilp >= ilp+1 by A54,AXIOMS:22; hence contradiction by REAL_1:69; end; then A62: h = mid(g,ilp+1,len g) by JORDAN3:def 4; then A63: ilp + len h = len g by A19,A22,AMI_5:4; A64: 1 <= ilp+n by A31,AXIOMS:22; then ilp+n -' 1 + 1 = ilp+n by AMI_5:4; then A65: ilp+n-'1 < len g by A25,A63,NAT_1:38; set m = mid(g,ilp+n,len g); m = g/^(ilp+n-'1) by A25,A63,JORDAN3:26; then A66: m/.len m in RightComp f by A2,A65,JORDAN4:18; A67: h/.n = g/.(n+(ilp+1)-'1) by A10,A13,A20,A24,A62,SPRECT_2:7 .= g/.(n+ilp+1-'1) by XCMPLX_1:1 .= g/.(ilp+n) by BINARITH:39; then A68: ilp+n <> len g by A2,A15,A26,XBOOLE_0:3; then reconsider m as S-Sequence_in_R2 by A11,A25,A63,A64,JORDAN3:39; ilp+n in dom g by A25,A63,A64,FINSEQ_3:27; then m/.1 in LeftComp f by A10,A15,A67,SPRECT_2:12; then L~f meets L~m by A66,Th50; then consider q being set such that A69: q in L~f and A70: q in L~m by XBOOLE_0:3; reconsider q as Point of TOP-REAL 2 by A70; consider i such that A71: 1 <= i & i+1 <= len m and A72: q in LSeg(m,i) by A70,SPPOL_2:13; A73: ilp+n < len g by A25,A63,A68,AXIOMS:21; len m = len g -' (ilp+n) + 1 by A11,A25,A63,A64,JORDAN3:27; then A74: i < len g -'(ilp+n) +1 by A71,NAT_1:38; then A75: LSeg(m,i) = LSeg(g,i+(ilp+n)-'1) by A64,A71,A73,JORDAN4:31; set j = i+(ilp+n)-'1; A76: j = i-'1+(ilp+n) by A71,JORDAN4:3; then A77: j >= ilp+n by NAT_1:29; ilp+1 < ilp+n by A30,REAL_1:53; then A78: j > ilp+1 by A77,AXIOMS:22; A79: now assume lp = q; then lp in LSeg(g,ilp) /\ LSeg(g,j) by A12,A72,A75,XBOOLE_0:def 3; then LSeg(g,ilp) meets LSeg(g,j) by XBOOLE_0:4; hence contradiction by A78,TOPREAL1:def 9; end; i-'1 < len g-'(ilp+n) by A71,A74,Th7; then i-'1+(ilp+n) < len g by Th6; then A80: j + 1 <= len g by A76,NAT_1:38; 1 <= j by A64,A77,AXIOMS:22; then ilp >= j by A4,A5,A12,A20,A27,A69,A72,A75,A79,A80,JORDAN5C:28; then ilp >= ilp+1 by A78,AXIOMS:22; hence contradiction by REAL_1:69; end; theorem for f being non constant standard special_circular_sequence st 1 <= i & i < len GoB f & 1 <= j & j < width GoB f holds Int cell(GoB f,i,j) misses L~SpStSeq L~f proof let f be non constant standard special_circular_sequence such that A1: 1 <= i & i < len GoB f and A2: 1 <= j & j < width GoB f; set G = GoB f; A3: Int cell(G,i,j) = { |[r,s]| where r,s is Real: G*(i,1)`1 < r & r < G*(i+1,1)`1 & G*(1,j)`2 < s & s < G*(1,j+1)`2 } by A1,A2,GOBOARD6:29; assume Int cell(GoB f,i,j) meets L~SpStSeq L~f; then consider x being set such that A4: x in Int cell(GoB f,i,j) and A5: x in L~SpStSeq L~f by XBOOLE_0:3; consider r,s being Real such that A6: x = |[r,s]| and A7: G*(i,1)`1 < r & r < G*(i+1,1)`1 and A8: G*(1,j)`2 < s & s < G*(1,j+1)`2 by A3,A4; A9: 1 <= width GoB f by GOBRD11:34; then A10: <*(GoB f)*(i,1)*> is_in_the_area_of f by A1,Th66; A11: 1 <= len GoB f by GOBRD11:34; then A12: <*(GoB f)*(1,j)*> is_in_the_area_of f by A2,Th66; 1 <= i+1 & i+1 <= len GoB f by A1,NAT_1:38; then A13: <*(GoB f)*(i+1,1)*> is_in_the_area_of f by A9,Th66; 1 <= j+1 & j+1 <= width GoB f by A2,NAT_1:38; then A14: <*(GoB f)*(1,j+1)*> is_in_the_area_of f by A11,Th66; L~SpStSeq L~f = { p: p`1 = W-bound L~SpStSeq L~f & p`2 <= N-bound L~SpStSeq L~f & p`2 >= S-bound L~SpStSeq L~f or p`1 <= E-bound L~SpStSeq L~f & p`1 >= W-bound L~SpStSeq L~f & p`2 = N-bound L~SpStSeq L~f or p`1 <= E-bound L~SpStSeq L~f & p`1 >= W-bound L~SpStSeq L~f & p`2 = S-bound L~SpStSeq L~f or p`1 = E-bound L~SpStSeq L~f & p`2 <= N-bound L~SpStSeq L~f & p`2 >= S-bound L~SpStSeq L~f} by Th52; then consider p such that A15: p = x and A16: p`1 = W-bound L~SpStSeq L~f & p`2 <= N-bound L~SpStSeq L~f & p`2 >= S-bound L~SpStSeq L~f or p`1 <= E-bound L~SpStSeq L~f & p`1 >= W-bound L~SpStSeq L~f & p`2 = N-bound L~SpStSeq L~f or p`1 <= E-bound L~SpStSeq L~f & p`1 >= W-bound L~SpStSeq L~f & p`2 = S-bound L~SpStSeq L~f or p`1 = E-bound L~SpStSeq L~f & p`2 <= N-bound L~SpStSeq L~f & p`2 >= S-bound L~SpStSeq L~f by A5; A17: p`1 = r by A6,A15,EUCLID:56; A18: p`2 = s by A6,A15,EUCLID:56; A19: W-bound L~SpStSeq L~f = W-bound L~f & S-bound L~SpStSeq L~f = S-bound L~f & N-bound L~SpStSeq L~f = N-bound L~f & E-bound L~SpStSeq L~f = E-bound L~f by SPRECT_1:66,67,68,69; per cases by A16; suppose A20: p`1 = W-bound L~SpStSeq L~f; A21: <*G*(i,1)*>/.1 = G*(i,1) by FINSEQ_4:25; 1 in dom<*G*(i,1)*> by FINSEQ_5:6; hence contradiction by A7,A10,A17,A19,A20,A21,SPRECT_2:def 1; suppose A22: p`2 = N-bound L~SpStSeq L~f; A23: <*G*(1,j+1)*>/.1 = G*(1,j+1) by FINSEQ_4:25; 1 in dom<*G*(1,j+1)*> by FINSEQ_5:6; hence contradiction by A8,A14,A18,A19,A22,A23,SPRECT_2:def 1; suppose that A24: p`2 = S-bound L~SpStSeq L~f; A25: <*G*(1,j)*>/.1 = G*(1,j) by FINSEQ_4:25; 1 in dom<*G*(1,j)*> by FINSEQ_5:6; hence contradiction by A8,A12,A18,A19,A24,A25,SPRECT_2:def 1; suppose that A26: p`1 = E-bound L~SpStSeq L~f; A27: <*G*(i+1,1)*>/.1 = G*(i+1,1) by FINSEQ_4:25; 1 in dom<*G*(i+1,1)*> by FINSEQ_5:6; hence contradiction by A7,A13,A17,A19,A26,A27,SPRECT_2:def 1; end; theorem for f, g being FinSequence of TOP-REAL 2, p being Point of TOP-REAL 2 st g is_in_the_area_of f & <*p*> is_in_the_area_of f & g is_S-Seq & p in L~g holds L_Cut(g,p) is_in_the_area_of f proof let f, g be FinSequence of TOP-REAL 2, p be Point of TOP-REAL 2 such that A1: g is_in_the_area_of f and A2: <*p*> is_in_the_area_of f and A3: g is_S-Seq; 2 <= len g by A3,TOPREAL1:def 10; then 1 <= len g by AXIOMS:22; then A4: len g in dom g by FINSEQ_3:27; assume p in L~g; then Index(p,g) < len g by JORDAN3:41; then A5: Index(p,g)+1 <= len g by NAT_1:38; 1<=Index(p,g)+1 by NAT_1:29; then A6: Index(p,g)+1 in dom g by A5,FINSEQ_3:27; per cases; suppose p<>g.(Index(p,g)+1); then A7: L_Cut(g,p) = <*p*>^mid(g,Index(p,g)+1,len g) by JORDAN3:def 4; mid(g,Index(p,g)+1,len g) is_in_the_area_of f by A1,A4,A6,SPRECT_2:26; hence L_Cut(g,p) is_in_the_area_of f by A2,A7,SPRECT_2:28; suppose p=g.(Index(p,g)+1); then L_Cut(g,p) = mid(g,Index(p,g)+1,len g) by JORDAN3:def 4; hence L_Cut(g,p) is_in_the_area_of f by A1,A4,A6,SPRECT_2:26; end;