Copyright (c) 1996 Association of Mizar Users
environ vocabulary PRE_TOPC, SQUARE_1, RELAT_2, CONNSP_1, SETFAM_1, TARSKI, BOOLE, CONNSP_3, SEQM_3, GOBOARD5, MATRIX_1, EUCLID, TOPREAL1, SUBSET_1, ARYTM_3, GOBOARD2, TREES_1, ARYTM_1, FINSEQ_1, MCART_1, GOBOARD1, METRIC_1, TOPS_1, PCOMPS_1, RELAT_1, FUNCT_1, ARYTM; notation TARSKI, XBOOLE_0, SUBSET_1, TOPREAL1, GOBOARD1, ORDINAL1, XREAL_0, REAL_1, NAT_1, SQUARE_1, BINARITH, STRUCT_0, PRE_TOPC, FINSEQ_1, MATRIX_1, METRIC_1, TOPS_1, CONNSP_1, PCOMPS_1, EUCLID, GOBOARD2, GOBOARD5, CONNSP_3; constructors REAL_1, SQUARE_1, BINARITH, TOPS_1, CONNSP_1, PCOMPS_1, GOBOARD2, GOBOARD9, CONNSP_3, MEMBERED; clusters STRUCT_0, GOBOARD5, RELSET_1, PRE_TOPC, GOBOARD2, EUCLID, TOPREAL1, XREAL_0, ARYTM_3, GOBOARD1, MEMBERED, ZFMISC_1; requirements REAL, NUMERALS, BOOLE, SUBSET, ARITHM; definitions TARSKI, XBOOLE_0; theorems TARSKI, NAT_1, REAL_1, REAL_2, AXIOMS, SPPOL_1, GOBOARD7, GOBOARD8, PRE_TOPC, CONNSP_1, SUBSET_1, EUCLID, CONNSP_3, GOBOARD5, TOPS_1, TOPMETR, RLVECT_1, SPPOL_2, SQUARE_1, GOBOARD1, METRIC_1, GOBOARD6, TOPREAL3, JORDAN1, ZFMISC_1, SETFAM_1, XBOOLE_0, XBOOLE_1, XREAL_0, XCMPLX_0, XCMPLX_1; schemes NAT_1; begin reserve i,j,k for Nat, r,s,r1,r2,s1,s2,sb,tb for Real, x for set, GX for non empty TopSpace; Lm1: sqrt 2>0 by SQUARE_1:93; theorem Th1: for A being Subset of GX, p being Point of GX st p in A & A is connected holds A c= skl p proof let A be Subset of GX, p be Point of GX; assume A1:p in A & A is connected; consider F being Subset-Family of GX such that A2: (for B being Subset of GX holds B in F iff B is connected & p in B) & union F = skl p by CONNSP_1:def 7; A3:A in F by A1,A2; A c= union F proof let x; thus thesis by A3,TARSKI:def 4; end; hence A c= skl p by A2; end; theorem for A,B,C being Subset of GX st C is_a_component_of GX & A c= C & B is connected & Cl A meets Cl B holds B c= C proof let A,B,C be Subset of GX; assume A1: C is_a_component_of GX & A c= C & B is connected & (Cl A) /\ (Cl B) <>{}; then consider p being Point of GX such that A2: p in (Cl A) /\ (Cl B) by SUBSET_1:10; reconsider C' = C as Subset of GX; C' is closed by A1,CONNSP_1:35; then Cl C = C by PRE_TOPC:52; then A3:Cl A c= C by A1,PRE_TOPC:49; A4: p in (Cl A) & p in (Cl B) by A2,XBOOLE_0:def 3; then A5:skl p=C' by A1,A3,CONNSP_1:44; Cl B is connected by A1,CONNSP_1:20; then A6:Cl B c= skl p by A4,Th1; B c= Cl B by PRE_TOPC:48; hence B c= C by A5,A6,XBOOLE_1:1; end; reserve GZ for non empty TopSpace; theorem for A,B being Subset of GZ st A is_a_component_of GZ & B is_a_component_of GZ holds A \/ B is a_union_of_components of GZ proof let A,B be Subset of GZ;assume A1:A is_a_component_of GZ & B is_a_component_of GZ; {A,B} c= bool (the carrier of GZ) proof let x;assume x in {A,B}; then x=A or x=B by TARSKI:def 2; hence x in bool (the carrier of GZ); end; then reconsider F2={A,B} as Subset-Family of GZ by SETFAM_1:def 7; reconsider F=F2 as Subset-Family of GZ; A2:for B1 being Subset of GZ st B1 in F holds B1 is_a_component_of GZ by A1,TARSKI:def 2; A \/ B=union F by ZFMISC_1:93; hence thesis by A2,CONNSP_3:def 2; end; theorem for B1,B2,V being Subset of GX holds Down(B1 \/ B2,V)=Down(B1,V) \/ Down(B2,V) proof let B1,B2,V be Subset of GX; Down(B1 \/ B2,V)=(B1 \/ B2)/\ V & Down(B1,V)=B1 /\ V & Down(B2,V)=B2 /\ V by CONNSP_3:def 5; hence Down(B1 \/ B2,V)=Down(B1,V) \/ Down(B2,V) by XBOOLE_1:23; end; theorem for B1,B2,V being Subset of GX holds Down(B1 /\ B2,V)=Down(B1,V) /\ Down(B2,V) proof let B1,B2,V be Subset of GX; A1:Down(B1 /\ B2,V)=(B1 /\ B2)/\ V & Down(B1,V)=B1 /\ V & Down(B2,V)=B2 /\ V by CONNSP_3:def 5; then Down(B1 /\ B2,V)=B1 /\(B2 /\ (V /\ V)) by XBOOLE_1:16 .=B1 /\(B2 /\ V /\ V) by XBOOLE_1:16 .= (B1 /\ V)/\ (B2 /\ V) by XBOOLE_1:16; hence Down(B1 /\ B2,V)=Down(B1,V) /\ Down(B2,V) by A1; end; reserve f for non constant standard special_circular_sequence, G for non empty-yielding Matrix of TOP-REAL 2; theorem Th6: (L~f)` <> {} proof LSeg(1/2*((GoB f)*(1,width GoB f -' 1)+(GoB f)*(1,width GoB f))-|[1,0]|, (GoB f)*(1,width GoB f)+|[-1,1]|) misses (L~f) by GOBOARD8:33; then LSeg(1/2*((GoB f)*(1,width GoB f -' 1)+(GoB f)*(1,width GoB f))-|[1,0 ]|, (GoB f)*(1,width GoB f)+|[-1,1]|) c= (L~f)` by SUBSET_1:43; hence thesis by XBOOLE_1:3; end; definition let f; cluster (L~f)` -> non empty; coherence by Th6; end; Lm2: the carrier of TOP-REAL 2 = REAL 2 by EUCLID:25; theorem for f holds the carrier of TOP-REAL 2 = union {cell(GoB f,i,j):i<=len GoB f & j<=width GoB f} proof let f; set j1=len GoB f, j2=width GoB f; thus the carrier of TOP-REAL 2 c= union {cell(GoB f,i,j):i<=j1 & j<=j2} proof let x;assume x in (the carrier of TOP-REAL 2); then reconsider p=x as Point of TOP-REAL 2; set r=p`1; A1: now assume A2: not( r<(GoB f)*(1,1)`1 or (GoB f)*(len GoB f,1)`1 <=r); now assume A3: not ex j st 1<=j & j<len GoB f & (GoB f)*(j,1)`1<=r & r<(GoB f)*(j+1,1)`1; then A4: 1<len GoB f implies r<(GoB f)*(1,1)`1 or (GoB f)*(1+1,1)`1<=r; defpred P[Nat] means $1=0 or(1<=$1 & $1<len GoB f implies (GoB f)*($1+1,1)`1<=r); A5: P[0]; A6: for k holds P[k] implies P[k+1] proof let k;assume A7: (k=0 or ( 1<=k & k<len GoB f implies (GoB f)*(k+1,1)`1<=r)); k+1=0 or(1<=k+1 & k+1<len GoB f implies (GoB f)*(k+1+1,1)`1<=r) proof (1<=k+1 & k+1<len GoB f implies (GoB f)*(k+1+1,1)`1<=r) proof assume A8:1<=k+1 & k+1<len GoB f; now assume A9:r< (GoB f)*(k+1+1,1)`1; then A10:k<>0 by A2,A4,GOBOARD7:34; 0<=k by NAT_1:18; then 0+1<=k by A10,NAT_1:38; hence contradiction by A3,A7,A8,A9,SPPOL_1:5; end; hence (GoB f)*(k+1+1,1)`1<=r; end; hence thesis; end; hence (k+1=0 or( 1<=k+1 & k+1<len GoB f implies (GoB f)*(k+1+1,1)`1<=r)); end; A11: for j holds P[j] from Ind(A5,A6); 1<len GoB f by GOBOARD7:34; then A12:1+1<=len GoB f by NAT_1:38; reconsider l=len GoB f as Nat; A13: 1+1-1<=l-1 by A12,REAL_1:49; l-1<l-1+1 by REAL_1:69; then A14:l-1<l by XCMPLX_1:27; then reconsider l1=l-1 as Nat by A13,SPPOL_1:7; 0<l1 by A13,AXIOMS:22; then (GoB f)*(l1+1,1)`1<=r by A11,A13,A14; hence contradiction by A2,XCMPLX_1:27; end; hence ex j st 1<=j & j<len GoB f & (GoB f)*(j,1)`1<=r & r<(GoB f)*(j+1,1)`1; end; now per cases by A1; case A15:r<(GoB f)*(1,1)`1; reconsider G=GoB f as Go-board; 1 <= 1 & 1 <= width G by GOBOARD7:35; then A16: v_strip(G,0) = { |[r1,s]| : r1 <= G*(1,1)`1 } by GOBOARD5:11; |[r,p`2]| in { |[r1,s]| : r1 <= (GoB f)*(1,1)`1 } by A15; then A17:p in v_strip(GoB f,0) by A16,EUCLID:57; 0<=j1 by NAT_1:18; hence ex j0 being Nat st j0<=j1 & x in v_strip(GoB f,j0) by A17; case A18:(GoB f)*(len GoB f,1)`1 <=r; reconsider G=GoB f as Go-board; 1 <= 1 & 1 <= width G by GOBOARD7:35; then A19: v_strip(G,len G) = { |[r1,s]| : G*(len G,1)`1<=r1} by GOBOARD5:10; |[r,p`2]| in { |[r1,s]| : (GoB f)*(len G,1)`1 <=r1} by A18; then p in v_strip(GoB f,len GoB f) by A19,EUCLID:57; hence ex j0 being Nat st j0<=j1 & x in v_strip(GoB f,j0); case ex j st 1<=j & j<len GoB f & (GoB f)*(j,1)`1<=r & r<(GoB f)*(j+1,1)`1; then consider j such that A20:1<=j & j<len GoB f & (GoB f)*(j,1)`1<=r & r<(GoB f)*(j+1,1)`1; reconsider G=GoB f as Go-board; 1 <= 1 & 1 <= width G by GOBOARD7:35; then A21: v_strip(G,j) = { |[r1,s]| : G*(j,1)`1<=r1 & r1<=G*(j+1,1)`1} by A20,GOBOARD5:9; |[r,p`2]| in { |[r1,s]| : G*(j,1)`1<=r1 & r1<=G* (j+1,1)`1 } by A20; then p in v_strip(GoB f,j) by A21,EUCLID:57; hence ex j0 being Nat st j0<=j1 & x in v_strip(GoB f,j0) by A20; end; then consider j0 being Nat such that A22:j0<=j1 & x in v_strip(GoB f,j0); set s=p`2; A23: now assume A24: not( s<(GoB f)*(1,1)`2 or (GoB f)*(1,width GoB f)`2 <=s); now assume A25: not ex j st 1<=j & j<width GoB f & (GoB f)*(1,j)`2<=s & s<(GoB f)*(1,j+1)`2; then A26: 1<width GoB f implies s<(GoB f)*(1,1)`2 or (GoB f)*(1,1+1)`2<=s; defpred P[Nat] means $1=0 or (1<=$1 & $1<width GoB f implies (GoB f)*(1,$1+1)`2<=s); A27: P[0]; A28: for k holds P[k] implies P[k+1] proof let k;assume A29: (k=0 or ( 1<=k & k<width GoB f implies (GoB f)*(1,k+1)`2<=s)); k+1=0 or(1<=k+1 & k+1<width GoB f implies (GoB f)*(1,k+1+1)`2<=s) proof (1<=k+1 & k+1<width GoB f implies (GoB f)*(1,k+1+1)`2<=s) proof assume A30:1<=k+1 & k+1<width GoB f; now assume A31:s< (GoB f)*(1,k+1+1)`2; then A32:k<>0 by A24,A26,GOBOARD7:35; 0<=k by NAT_1:18; then 0+1<=k by A32,NAT_1:38; hence contradiction by A25,A29,A30,A31,SPPOL_1:5; end; hence (GoB f)*(1,k+1+1)`2<=s; end; hence thesis; end; hence (k+1=0 or( 1<=k+1 & k+1<width GoB f implies (GoB f)*(1,k+1+1)`2<=s)); end; A33: for j holds P[j] from Ind(A27,A28); 1<width GoB f by GOBOARD7:35; then A34:1+1<=width GoB f by NAT_1:38; reconsider l=width GoB f as Nat; A35: 1+1-1<=l-1 by A34,REAL_1:49; l-1<l-1+1 by REAL_1:69; then A36:l-1<l by XCMPLX_1:27; then reconsider l1=l-1 as Nat by A35,SPPOL_1:7; 0<l1 by A35,AXIOMS:22; then (GoB f)*(1,l1+1)`2<=s by A33,A35,A36; hence contradiction by A24,XCMPLX_1:27; end; hence ex j st 1<=j & j<width GoB f & (GoB f)*(1,j)`2<=s & s<(GoB f)*(1,j+1)`2; end; now per cases by A23; case A37:s<(GoB f)*(1,1)`2; reconsider G=GoB f as Go-board; 1 <= len G by GOBOARD7:34; then A38: h_strip(G,0) = { |[r1,s1]| : s1 <= G*(1,1)`2 } by GOBOARD5:8; |[r,s]| in { |[r1,s1]| : s1 <= (GoB f)*(1,1)`2 } by A37; then A39:p in h_strip(GoB f,0) by A38,EUCLID:57; 0<=j2 by NAT_1:18; hence ex i0 being Nat st i0<=j2 & x in h_strip(GoB f,i0) by A39; case A40:(GoB f)*(1,width GoB f)`2 <=s; reconsider G=GoB f as Go-board; 1 <= 1 & 1 <= len G by GOBOARD7:34; then A41: h_strip(G,width G) = { |[r1,s1]| : G*(1,width G)`2<=s1} by GOBOARD5:7; |[r,s]| in { |[r1,s1]| : (GoB f)*(1,width G)`2 <=s1} by A40; then p in h_strip(GoB f,width GoB f) by A41,EUCLID:57; hence ex i0 being Nat st i0<=j2 & x in h_strip(GoB f,i0); case ex j st 1<=j & j<width GoB f & (GoB f)*(1,j)`2<=s & s<(GoB f)*(1,j+1)`2; then consider j such that A42:1<=j & j<width GoB f & (GoB f)*(1,j)`2<=s & s<(GoB f)*(1,j+1)`2; reconsider G=GoB f as Go-board; 1 <= 1 & 1 <= len G by GOBOARD7:34; then A43: h_strip(G,j) = { |[r1,s1]| : G*(1,j)`2<=s1 & s1<=G*(1,j+1)`2} by A42,GOBOARD5:6; |[r,s]| in { |[r1,s1]| : G*(1,j)`2<=s1 & s1<=G* (1,j+1)`2 } by A42; then p in h_strip(GoB f,j) by A43,EUCLID:57; hence ex i0 being Nat st i0<=j2 & x in h_strip(GoB f,i0) by A42; end; then consider i0 being Nat such that A44:i0<=j2 & x in h_strip(GoB f,i0); A45: x in v_strip(GoB f,j0) /\ h_strip(GoB f,i0) by A22,A44,XBOOLE_0:def 3; reconsider X0=cell(GoB f,j0,i0) as set; x in X0 & X0 in {cell(GoB f,i,j):i<=j1 & j<=j2} by A22,A44,A45,GOBOARD5:def 3; hence x in union {cell(GoB f,i,j):i<=j1 & j<=j2} by TARSKI:def 4; end; let x;assume x in union {cell(GoB f,i,j):i<=j1 & j<=j2}; then consider X0 being set such that A46:x in X0 & X0 in {cell(GoB f,i,j):i<=j1 & j<=j2} by TARSKI:def 4; ex i,j st X0=cell(GoB f,i,j) &(i<=j1 & j<=j2) by A46; hence x in the carrier of TOP-REAL 2 by A46; end; Lm3: for s1 holds { |[ tb,sb ]|:sb>=s1} is Subset of TOP-REAL 2 proof let s1; { |[ tb,sb ]|:sb>=s1} c= REAL 2 proof let y be set;assume y in { |[ tb,sb ]|:sb>=s1}; then ex t7,s7 being Real st |[ t7,s7 ]|=y & s7>=s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm4: for s1 holds { |[ tb,sb ]|:sb>s1} is Subset of TOP-REAL 2 proof let s1; { |[ tb,sb ]|:sb>s1} c= REAL 2 proof let y be set;assume y in { |[ tb,sb ]|:sb>s1}; then ex t7,s7 being Real st |[ t7,s7 ]|=y & s7>s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm5: for s1 holds { |[ tb,sb ]|:sb<=s1} is Subset of TOP-REAL 2 proof let s1; { |[ tb,sb ]|:sb<=s1} c= REAL 2 proof let y be set;assume y in { |[ tb,sb ]|:sb<=s1}; then ex t7,s7 being Real st |[ t7,s7 ]|=y & s7<=s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm6: for s1 holds { |[ tb,sb ]|:sb<s1} is Subset of TOP-REAL 2 proof let s1; { |[ tb,sb ]|:sb<s1} c= REAL 2 proof let y be set;assume y in { |[ tb,sb ]|:sb<s1}; then ex t7,s7 being Real st |[ t7,s7 ]|=y & s7<s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm7: for s1 holds { |[ sb,tb ]|:sb<=s1} is Subset of TOP-REAL 2 proof let s1; { |[ sb,tb ]|:sb<=s1} c= REAL 2 proof let y be set;assume y in { |[ sb,tb ]|:sb<=s1}; then ex s7,t7 being Real st |[ s7,t7 ]|=y & s7<=s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm8: for s1 holds { |[ sb,tb ]|:sb<s1} is Subset of TOP-REAL 2 proof let s1; { |[ sb,tb ]|:sb<s1} c= REAL 2 proof let y be set;assume y in { |[ sb,tb ]|:sb<s1}; then ex s7,t7 being Real st |[ s7,t7 ]|=y & s7<s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm9: for s1 holds { |[ sb,tb ]|:sb>=s1} is Subset of TOP-REAL 2 proof let s1; { |[ sb,tb ]|:sb>=s1} c= REAL 2 proof let y be set;assume y in { |[ sb,tb ]|:sb>=s1}; then ex s7,t7 being Real st |[ s7,t7 ]|=y & s7>=s1; hence thesis by Lm2; end; hence thesis by Lm2; end; Lm10: for s1 holds { |[ sb,tb ]|:sb>s1} is Subset of TOP-REAL 2 proof let s1; { |[ sb,tb ]|:sb>s1} c= REAL 2 proof let y be set;assume y in { |[ sb,tb ]|:sb>s1}; then ex s7,t7 being Real st |[ s7,t7 ]|=y & s7>s1; hence thesis by Lm2; end; hence thesis by Lm2; end; theorem Th8: for P1,P2 being Subset of TOP-REAL 2 st P1={ |[r,s]| : s <= s1 } & P2={ |[r2,s2]| : s2 > s1 } holds P1=P2` proof let P1,P2 be Subset of TOP-REAL 2; assume A1: P1={ |[r,s]| : s <= s1 } & P2={ |[r2,s2]| : s2 > s1 }; A2: P1 c= P2` proof let x;assume x in P1; then consider r,s such that A3:|[r,s]|=x & ( s <= s1) by A1; for r2,s2 holds not (|[r2,s2]|=x & s2 > s1) by A3,SPPOL_2:1; then x in (REAL 2) & not x in P2 by A1,A3,Lm2; then x in (REAL 2) \ P2 by XBOOLE_0:def 4; then x in (the carrier of TOP-REAL 2) \ P2 by EUCLID:25; hence thesis by SUBSET_1:def 5; end; P2` c= P1 proof let x;assume x in P2`; then x in (the carrier of TOP-REAL 2) \ P2 by SUBSET_1:def 5; then x in (REAL 2) \ P2 by EUCLID:25; then A4:x in (REAL 2) & not x in P2 by XBOOLE_0:def 4; then reconsider p=x as Point of TOP-REAL 2 by EUCLID:25; A5:p=|[p`1,p`2]| by EUCLID:57; then p`2 <= s1 by A1,A4; hence thesis by A1,A5; end; hence P1=P2` by A2,XBOOLE_0:def 10; end; theorem Th9: for P1,P2 being Subset of TOP-REAL 2 st P1={ |[r,s]| : s >= s1 } & P2={ |[r2,s2]| : s2 < s1 } holds P1=P2` proof let P1,P2 be Subset of TOP-REAL 2; assume A1: P1={ |[r,s]| : s >= s1 } & P2={ |[r2,s2]| : s2 < s1 }; A2: P1 c= P2` proof let x;assume x in P1; then consider r,s such that A3:|[r,s]|=x & ( s >= s1) by A1; not ex r2,s2 st |[r2,s2]|=x & s2 < s1 by A3,SPPOL_2:1; then not x in P2 by A1; then x in (the carrier of TOP-REAL 2) \ P2 by A3,XBOOLE_0:def 4; hence thesis by SUBSET_1:def 5; end; P2` c= P1 proof let x;assume x in P2`; then x in (the carrier of TOP-REAL 2) \ P2 by SUBSET_1:def 5; then x in (REAL 2) \ P2 by EUCLID:25; then A4:x in (REAL 2) & not x in P2 by XBOOLE_0:def 4; then reconsider p=x as Point of TOP-REAL 2 by EUCLID:25; A5:p=|[p`1,p`2]| by EUCLID:57; then p`2 >= s1 by A1,A4; hence thesis by A1,A5; end; hence P1=P2` by A2,XBOOLE_0:def 10; end; theorem Th10: for P1,P2 being Subset of TOP-REAL 2 st P1={ |[s,r]| : s >= s1 } & P2={ |[s2,r2]| : s2 < s1 } holds P1=P2` proof let P1,P2 be Subset of TOP-REAL 2; assume A1: P1={ |[s,r]| : s >= s1 } & P2={ |[s2,r2]| : s2 < s1 }; A2: P1 c= P2` proof let x;assume x in P1; then consider s,r such that A3:|[s,r]|=x & ( s >= s1) by A1; not ex s2,r2 st |[s2,r2]|=x & s2 < s1 by A3,SPPOL_2:1; then not x in P2 by A1; then x in (the carrier of TOP-REAL 2) \ P2 by A3,XBOOLE_0:def 4; hence thesis by SUBSET_1:def 5; end; P2` c= P1 proof let x;assume x in P2`; then x in (the carrier of TOP-REAL 2) \ P2 by SUBSET_1:def 5; then x in (REAL 2) \ P2 by EUCLID:25; then A4:x in (REAL 2) & not x in P2 by XBOOLE_0:def 4; then reconsider p=x as Point of TOP-REAL 2 by EUCLID:25; A5:p=|[p`1,p`2]| by EUCLID:57; then p`1 >= s1 by A1,A4; hence thesis by A1,A5; end; hence P1=P2` by A2,XBOOLE_0:def 10; end; theorem Th11: for P1,P2 being Subset of TOP-REAL 2 st P1={ |[s,r]| : s <= s1 } & P2={ |[s2,r2]| : s2 > s1 } holds P1=P2` proof let P1,P2 be Subset of TOP-REAL 2; assume A1: P1={ |[s,r]| : s <= s1 } & P2={ |[s2,r2]| : s2 > s1 }; A2: P1 c= P2` proof let x;assume x in P1; then consider s,r such that A3:|[s,r]|=x & ( s <= s1) by A1; not ex s2,r2 st |[s2,r2]|=x & s2 > s1 by A3,SPPOL_2:1; then not x in { |[s2,r2]| : s2 > s1 }; then x in (the carrier of TOP-REAL 2) \ P2 by A1,A3,XBOOLE_0:def 4; hence thesis by SUBSET_1:def 5; end; P2` c= P1 proof let x;assume x in P2`; then x in (the carrier of TOP-REAL 2) \ P2 by SUBSET_1:def 5; then x in (REAL 2) \ P2 by EUCLID:25; then A4:x in (REAL 2) & not x in P2 by XBOOLE_0:def 4; then reconsider p=x as Point of TOP-REAL 2 by EUCLID:25; A5:p=|[p`1,p`2]| by EUCLID:57; then p`1 <= s1 by A1,A4; hence thesis by A1,A5; end; hence P1=P2` by A2,XBOOLE_0:def 10; end; theorem Th12: for P being Subset of TOP-REAL 2, s1 st P= { |[r,s]| : s <= s1 } holds P is closed proof let P be Subset of TOP-REAL 2, s1; assume A1:P= { |[r,s]| : s <= s1 }; reconsider P1= { |[r,s]| : s > s1 } as Subset of TOP-REAL 2 by Lm4; A2:P=P1` by A1,Th8; P1 is open by JORDAN1:27; hence P is closed by A2,TOPS_1:30; end; theorem Th13: for P being Subset of TOP-REAL 2,s1 st P={ |[r,s]| : s1 <= s } holds P is closed proof let P be Subset of TOP-REAL 2, s1; assume A1:P= { |[r,s]| : s1 <= s }; reconsider P1= { |[r,s]| : s1 > s } as Subset of TOP-REAL 2 by Lm6; A2:P=P1` by A1,Th9; P1 is open by JORDAN1:28; hence P is closed by A2,TOPS_1:30; end; theorem Th14: for P being Subset of TOP-REAL 2, s1 st P= { |[s,r]| : s <= s1 } holds P is closed proof let P be Subset of TOP-REAL 2, s1; assume A1:P= { |[s,r]| : s <= s1 }; reconsider P1= { |[s,r]| : s > s1 } as Subset of TOP-REAL 2 by Lm10; A2:P=P1` by A1,Th11; P1 is open by JORDAN1:25; hence P is closed by A2,TOPS_1:30; end; theorem Th15: for P being Subset of TOP-REAL 2,s1 st P={ |[s,r]| : s1 <= s } holds P is closed proof let P be Subset of TOP-REAL 2, s1; assume A1:P= { |[s,r]| : s >= s1 }; reconsider P1= { |[s,r]| : s < s1 } as Subset of TOP-REAL 2 by Lm8; A2:P=P1` by A1,Th10; P1 is open by JORDAN1:26; hence P is closed by A2,TOPS_1:30; end; theorem Th16: for G being Matrix of TOP-REAL 2 holds h_strip(G,j) is closed proof let G be Matrix of TOP-REAL 2; now per cases; case A1:j<1; A2:now assume j >= width G; then h_strip(G,j)={ |[r,s]| : G*(1,j)`2 <= s } by GOBOARD5:def 2; hence h_strip(G,j) is closed by Th13; end; now assume j<width G; then h_strip(G,j) = { |[r,s]| : s <= G*(1,j+1)`2 } by A1,GOBOARD5:def 2; hence h_strip(G,j) is closed by Th12; end; hence h_strip(G,j) is closed by A2; case 1 <= j & j < width G; then A3: h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } by GOBOARD5:def 2; A4:{ |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 }= { |[r1,s1]| : G*(1,j)`2 <= s1} /\ {|[r2,s2]| : s2 <= G*(1,j+1)`2 } proof A5: { |[r1,s1]| : G*(1,j)`2 <= s1} /\ {|[r2,s2]| : s2 <= G*(1,j+1)`2 } c= { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof let x;assume x in { |[r1,s1]| : G*(1,j)`2 <= s1} /\ {|[r2,s2]| : s2 <= G* (1,j+1)`2 }; then A6:x in { |[r1,s1]| : G*(1,j)`2 <= s1} & x in {|[r2,s2]| : s2 <= G*(1,j+1)`2 } by XBOOLE_0:def 3; then consider r1,s1 such that A7: |[r1,s1]|=x & G*(1,j)`2 <= s1; consider r2,s2 such that A8: |[r2,s2]|=x & s2 <= G*(1,j+1)`2 by A6; r1=r2 & s1=s2 by A7,A8,SPPOL_2:1; hence thesis by A7,A8; end; A9:{ |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } c= {|[r1,s1]| : s1 <= G*(1,j+1)`2 } proof let x;assume x in { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 }; then ex r,s st x=|[r,s]| &(G*(1,j)`2 <= s & s <= G*(1,j+1)`2); hence thesis; end; { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } c= {|[r1,s1]| : G*(1,j)`2 <= s1 } proof let x;assume x in { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 }; then ex r,s st x=|[r,s]| &(G*(1,j)`2 <= s & s <= G*(1,j+1)`2); hence thesis; end; then { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } c= { |[r1,s1]| : G*(1,j)`2 <= s1} /\ {|[r2,s2]| : s2 <= G*(1,j+1)`2 } by A9,XBOOLE_1:19; hence thesis by A5,XBOOLE_0:def 10; end; reconsider P1={ |[r1,s1]| : G*(1,j)`2 <= s1} as Subset of TOP-REAL 2 by Lm3; reconsider P2={ |[r1,s1]| : s1<= G*(1,j+1)`2 } as Subset of TOP-REAL 2 by Lm5; A10:P1 is closed by Th13; P2 is closed by Th12; hence h_strip(G,j) is closed by A3,A4,A10,TOPS_1:35; case j >= width G; then h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s } by GOBOARD5:def 2; hence h_strip(G,j) is closed by Th13; end; hence thesis; end; theorem Th17: for G being Matrix of TOP-REAL 2 holds v_strip(G,j) is closed proof let G be Matrix of TOP-REAL 2; now per cases; case A1:j<1; A2:now assume j >= len G; then v_strip(G,j)={ |[s,r]| : G*(j,1)`1 <= s } by GOBOARD5:def 1; hence v_strip(G,j) is closed by Th15; end; now assume j<len G; then v_strip(G,j) = { |[s,r]| : s <= G*(j+1,1)`1 } by A1,GOBOARD5:def 1; hence v_strip(G,j) is closed by Th14; end; hence v_strip(G,j) is closed by A2; case 1 <= j & j < len G; then A3: v_strip(G,j) = { |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 } by GOBOARD5:def 1; A4:{ |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 }= { |[s1,r1]| : G*(j,1)`1 <= s1} /\ {|[s2,r2]| : s2 <= G*(j+1,1)`1 } proof A5: { |[s1,r1]| : G*(j,1)`1 <= s1} /\ {|[s2,r2]| : s2 <= G*(j+1,1)`1 } c= { |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 } proof let x;assume x in { |[s1,r1]| : G*(j,1)`1 <= s1} /\ {|[s2,r2]| : s2 <= G* (j+1,1)`1 }; then A6:x in { |[s1,r1]| : G*(j,1)`1 <= s1} & x in {|[s2,r2]| : s2 <= G*(j+1,1)`1 } by XBOOLE_0:def 3; then ex s1,r1 st |[s1,r1]|=x & G*(j,1)`1 <= s1; then consider r1,s1 such that A7: |[s1,r1]|=x & G*(j,1)`1 <= s1; consider s2,r2 such that A8: |[s2,r2]|=x & s2 <= G*(j+1,1)`1 by A6; r1=r2 & s1=s2 by A7,A8,SPPOL_2:1; hence thesis by A7,A8; end; A9:{ |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 } c= {|[s1,r1]| : s1 <= G*(j+1,1)`1 } proof let x;assume x in { |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 }; then ex s,r st x=|[s,r]| &(G*(j,1)`1 <= s & s <= G*(j+1,1)`1); hence thesis; end; { |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 } c= {|[s1,r1]| : G*(j,1)`1 <= s1 } proof let x;assume x in { |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 }; then ex s,r st x=|[s,r]| &(G*(j,1)`1 <= s & s <= G*(j+1,1)`1); hence thesis; end; then { |[s,r]| : G*(j,1)`1 <= s & s <= G*(j+1,1)`1 } c= { |[s1,r1]| : G*(j,1)`1 <= s1} /\ {|[s2,r2]| : s2 <= G*(j+1,1)`1 } by A9,XBOOLE_1:19; hence thesis by A5,XBOOLE_0:def 10; end; reconsider P1={ |[s1,r1]| : G*(j,1)`1 <= s1} as Subset of TOP-REAL 2 by Lm9; reconsider P2={ |[s1,r1]| : s1<= G*(j+1,1)`1 } as Subset of TOP-REAL 2 by Lm7; A10:P1 is closed by Th15; P2 is closed by Th14; hence v_strip(G,j) is closed by A3,A4,A10,TOPS_1:35; case j >= len G; then v_strip(G,j) = { |[s,r]| : G*(j,1)`1 <= s } by GOBOARD5:def 1; hence v_strip(G,j) is closed by Th15; end; hence thesis; end; theorem Th18: G is X_equal-in-line implies v_strip(G,0) = { |[r,s]| : r <= G*(1,1)`1 } proof assume A1: G is X_equal-in-line; 0 <> width G by GOBOARD1:def 5; then 1 <= width G by RLVECT_1:99; hence thesis by A1,GOBOARD5:11; end; theorem Th19: G is X_equal-in-line implies v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 <= r } proof assume A1: G is X_equal-in-line; 0 <> width G by GOBOARD1:def 5; then 1 <= width G by RLVECT_1:99; hence thesis by A1,GOBOARD5:10; end; theorem Th20: G is X_equal-in-line & 1 <= i & i < len G implies v_strip(G,i) = { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 } proof assume A1: G is X_equal-in-line; assume A2: 1 <= i & i < len G; 0 <> width G by GOBOARD1:def 5; then 1 <= width G by RLVECT_1:99; hence thesis by A1,A2,GOBOARD5:9; end; theorem Th21: G is Y_equal-in-column implies h_strip(G,0) = { |[r,s]| : s <= G*(1,1)`2 } proof assume A1: G is Y_equal-in-column; 0 <> len G by GOBOARD1:def 5; then 1 <= len G by RLVECT_1:99; hence thesis by A1,GOBOARD5:8; end; theorem Th22: G is Y_equal-in-column implies h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 <= s } proof assume A1: G is Y_equal-in-column; 0 <> len G by GOBOARD1:def 5; then 1 <= len G by RLVECT_1:99; hence thesis by A1,GOBOARD5:7; end; theorem Th23: G is Y_equal-in-column & 1 <= j & j < width G implies h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof assume A1: G is Y_equal-in-column; assume A2: 1 <= j & j < width G; 0 <> len G by GOBOARD1:def 5; then 1 <= len G by RLVECT_1:99; hence thesis by A1,A2,GOBOARD5:6; end; reserve G for non empty-yielding X_equal-in-line Y_equal-in-column Matrix of TOP-REAL 2; theorem Th24: cell(G,0,0) = { |[r,s]| : r <= G*(1,1)`1 & s <= G*(1,1)`2 } proof A1: cell(G,0,0) = v_strip(G,0) /\ h_strip(G,0) by GOBOARD5:def 3; A2: v_strip(G,0) = { |[r,s]| : r <= G*(1,1)`1 } by Th18; A3: h_strip(G,0) = { |[r,s]| : s <= G*(1,1)`2 } by Th21; thus cell(G,0,0) c= { |[r,s]| : r <= G*(1,1)`1 & s <= G*(1,1)`2 } proof let x be set; assume A4: x in cell(G,0,0); then x in v_strip(G,0) by A1,XBOOLE_0:def 3; then consider r1,s1 such that A5: x = |[r1,s1]| and A6: r1 <= G*(1,1)`1 by A2; x in h_strip(G,0) by A1,A4,XBOOLE_0:def 3; then consider r2,s2 such that A7: x = |[r2,s2]| and A8: s2 <= G*(1,1)`2 by A3; r1 = r2 & s1 = s2 by A5,A7,SPPOL_2:1; hence thesis by A5,A6,A8; end; let x be set; assume x in { |[r,s]| : r <= G*(1,1)`1 & s <= G*(1,1)`2 }; then ex r,s st x = |[r,s]| & r <= G*(1,1)`1 & s <= G*(1,1)`2; then x in v_strip(G,0) & x in h_strip(G,0) by A2,A3; hence thesis by A1,XBOOLE_0:def 3; end; theorem Th25: cell(G,0,width G) = { |[r,s]| : r <= G*(1,1)`1 & G*(1,width G)`2 <= s } proof A1:cell(G,0,width G) = v_strip(G,0) /\ h_strip(G,width G) by GOBOARD5:def 3; A2: v_strip(G,0) = { |[r,s]| : r <= G*(1,1)`1 } by Th18; A3: h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 <= s } by Th22; thus cell(G,0,width G) c= { |[r,s]| : r <= G*(1,1)`1 & G*(1,width G)`2 <= s } proof let x be set; assume A4: x in cell(G,0,width G); then x in v_strip(G,0) by A1,XBOOLE_0:def 3; then consider r1,s1 such that A5: x = |[r1,s1]| and A6: r1 <= G*(1,1)`1 by A2; x in h_strip(G,width G) by A1,A4,XBOOLE_0:def 3; then consider r2,s2 such that A7: x = |[r2,s2]| and A8: G*(1,width G)`2 <= s2 by A3; r1 = r2 & s1 = s2 by A5,A7,SPPOL_2:1; hence thesis by A5,A6,A8; end; let x be set; assume x in { |[r,s]| : r <= G*(1,1)`1 & G*(1,width G)`2 <= s }; then ex r,s st x = |[r,s]| & r <= G*(1,1)`1 & G*(1,width G)`2 <= s; then x in v_strip(G,0) & x in h_strip(G,width G) by A2,A3; hence thesis by A1,XBOOLE_0:def 3; end; theorem Th26: 1 <= j & j < width G implies cell(G,0,j) = { |[r,s]| : r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof assume A1: 1 <= j & j < width G; A2: cell(G,0,j) = v_strip(G,0) /\ h_strip(G,j) by GOBOARD5:def 3; A3: v_strip(G,0) = { |[r,s]| : r <= G*(1,1)`1 } by Th18; A4: h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } by A1,Th23; thus cell(G,0,j) c= { |[r,s]| : r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof let x be set; assume A5: x in cell(G,0,j); then x in v_strip(G,0) by A2,XBOOLE_0:def 3; then consider r1,s1 such that A6: x = |[r1,s1]| and A7: r1 <= G*(1,1)`1 by A3; x in h_strip(G,j) by A2,A5,XBOOLE_0:def 3; then consider r2,s2 such that A8: x = |[r2,s2]| and A9: G*(1,j)`2 <= s2 & s2 <= G*(1,j+1)`2 by A4; r1 = r2 & s1 = s2 by A6,A8,SPPOL_2:1; hence thesis by A6,A7,A9; end; let x be set; assume x in { |[r,s]| : r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <= G* (1,j+1)`2 }; then ex r,s st x = |[r,s]| & r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2; then x in v_strip(G,0) & x in h_strip(G,j) by A3,A4; hence thesis by A2,XBOOLE_0:def 3; end; Lm11:Euclid 2=MetrStruct(#REAL 2,Pitag_dist 2#) by EUCLID:def 7; theorem Th27: cell(G,len G,0) = { |[r,s]| : G*(len G,1)`1 <= r & s <= G*(1,1)`2 } proof A1:cell(G,len G,0) = v_strip(G,len G) /\ h_strip(G,0) by GOBOARD5:def 3; A2: v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 <= r } by Th19; A3: h_strip(G,0) = { |[r,s]| : s <= G*(1,1)`2 } by Th21; thus cell(G,len G,0) c= { |[r,s]| : G*(len G,1)`1 <= r & s <= G*(1,1)`2 } proof let x be set; assume A4: x in cell(G,len G,0); then x in v_strip(G,len G) by A1,XBOOLE_0:def 3; then consider r1,s1 such that A5: x = |[r1,s1]| and A6: G*(len G,1)`1 <= r1 by A2; x in h_strip(G,0) by A1,A4,XBOOLE_0:def 3; then consider r2,s2 such that A7: x = |[r2,s2]| and A8: s2 <= G*(1,1)`2 by A3; r1 = r2 & s1 = s2 by A5,A7,SPPOL_2:1; hence thesis by A5,A6,A8; end; let x be set; assume x in { |[r,s]| : G*(len G,1)`1 <= r & s <= G*(1,1)`2 }; then ex r,s st x = |[r,s]| & G*(len G,1)`1 <= r & s <= G*(1,1)`2; then x in v_strip(G,len G) & x in h_strip(G,0) by A2,A3; hence thesis by A1,XBOOLE_0:def 3; end; theorem Th28: cell(G,len G,width G) = { |[r,s]| : G*(len G,1)`1 <= r & G*(1,width G)`2 <= s } proof A1:cell(G,len G,width G) = v_strip(G,len G) /\ h_strip(G,width G) by GOBOARD5:def 3; A2: v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 <= r } by Th19; A3: h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 <= s } by Th22; thus cell(G,len G,width G) c= { |[r,s]| : G*(len G,1)`1 <= r & G*(1,width G)`2 <= s } proof let x be set; assume A4: x in cell(G,len G,width G); then x in v_strip(G,len G) by A1,XBOOLE_0:def 3; then consider r1,s1 such that A5: x = |[r1,s1]| and A6: G*(len G,1)`1 <= r1 by A2; x in h_strip(G,width G) by A1,A4,XBOOLE_0:def 3; then consider r2,s2 such that A7: x = |[r2,s2]| and A8: G*(1,width G)`2 <= s2 by A3; r1 = r2 & s1 = s2 by A5,A7,SPPOL_2:1; hence thesis by A5,A6,A8; end; let x be set; assume x in { |[r,s]| : G*(len G,1)`1 <= r & G*(1,width G)`2 <= s }; then ex r,s st x = |[r,s]| & G*(len G,1)`1 <= r & G*(1,width G)`2 <= s; then x in v_strip(G,len G) & x in h_strip(G,width G) by A2,A3; hence thesis by A1,XBOOLE_0:def 3; end; theorem Th29: 1 <= j & j < width G implies cell(G,len G,j) = { |[r,s]| : G*(len G,1)`1 <= r & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof assume A1: 1 <= j & j < width G; A2: cell(G,len G,j) = v_strip(G,len G) /\ h_strip(G,j) by GOBOARD5:def 3; A3: v_strip(G,len G) = { |[r,s]| : G*(len G,1)`1 <= r } by Th19; A4: h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s & s <= G* (1,j+1)`2 } by A1,Th23; thus cell(G,len G,j) c= { |[r,s]| : G*(len G,1)`1 <= r & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof let x be set; assume A5: x in cell(G,len G,j); then x in v_strip(G,len G) by A2,XBOOLE_0:def 3; then consider r1,s1 such that A6: x = |[r1,s1]| and A7: G*(len G,1)`1 <= r1 by A3; x in h_strip(G,j) by A2,A5,XBOOLE_0:def 3; then consider r2,s2 such that A8: x = |[r2,s2]| and A9: G*(1,j)`2 <= s2 & s2 <= G*(1,j+1)`2 by A4; r1 = r2 & s1 = s2 by A6,A8,SPPOL_2:1; hence thesis by A6,A7,A9; end; let x be set; assume x in { |[r,s]| : G*(len G,1)`1 <= r & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 }; then ex r,s st x = |[r,s]| & G*(len G,1)`1 <= r & G*(1,j)`2 <= s & s <= G*(1,j+1)`2; then x in v_strip(G,len G) & x in h_strip(G,j) by A3,A4; hence thesis by A2,XBOOLE_0:def 3; end; theorem Th30: 1 <= i & i < len G implies cell(G,i,0) = { |[r,s]|: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & s <= G* (1,1)`2 } proof assume A1: 1 <= i & i < len G; A2: cell(G,i,0) = v_strip(G,i) /\ h_strip(G,0) by GOBOARD5:def 3; A3: v_strip(G,i) = { |[r,s]| : G*(i,1)`1 <= r & r <= G* (i+1,1)`1 } by A1,Th20; A4: h_strip(G,0) = { |[r,s]| : s <= G*(1,1)`2 } by Th21; thus cell(G,i,0) c= { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & s <= G*(1,1)`2 } proof let x be set; assume A5: x in cell(G,i,0); then x in v_strip(G,i) by A2,XBOOLE_0:def 3; then consider r1,s1 such that A6: x = |[r1,s1]| and A7: G*(i,1)`1 <= r1 & r1 <= G*(i+1,1)`1 by A3; x in h_strip(G,0) by A2,A5,XBOOLE_0:def 3; then consider r2,s2 such that A8: x = |[r2,s2]| and A9: s2 <= G*(1,1)`2 by A4; r1 = r2 & s1 = s2 by A6,A8,SPPOL_2:1; hence thesis by A6,A7,A9; end; let x be set; assume x in { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & s <= G* (1,1)`2 }; then ex r,s st x = |[r,s]| & G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & s <= G*(1,1)`2; then x in v_strip(G,i) & x in h_strip(G,0) by A3,A4; hence thesis by A2,XBOOLE_0:def 3; end; theorem Th31: 1 <= i & i < len G implies cell(G,i,width G) = { |[r,s]|: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,width G)`2 <= s } proof assume A1: 1 <= i & i < len G; A2: cell(G,i,width G) = v_strip(G,i) /\ h_strip(G,width G) by GOBOARD5:def 3; A3: v_strip(G,i) = { |[r,s]| : G*(i,1)`1 <= r & r <= G* (i+1,1)`1 } by A1,Th20; A4: h_strip(G,width G) = { |[r,s]| : G*(1,width G)`2 <= s } by Th22; thus cell(G,i,width G) c= { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,width G)`2 <= s } proof let x be set; assume A5: x in cell(G,i,width G); then x in v_strip(G,i) by A2,XBOOLE_0:def 3; then consider r1,s1 such that A6: x = |[r1,s1]| and A7: G*(i,1)`1 <= r1 & r1 <= G*(i+1,1)`1 by A3; x in h_strip(G,width G) by A2,A5,XBOOLE_0:def 3; then consider r2,s2 such that A8: x = |[r2,s2]| and A9: G*(1,width G)`2 <= s2 by A4; r1 = r2 & s1 = s2 by A6,A8,SPPOL_2:1; hence thesis by A6,A7,A9; end; let x be set; assume x in { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G* (1,width G)`2 <= s }; then ex r,s st x = |[r,s]| & G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,width G)`2 <= s; then x in v_strip(G,i) & x in h_strip(G,width G) by A3,A4; hence thesis by A2,XBOOLE_0:def 3; end; theorem Th32: 1 <= i & i < len G & 1 <= j & j < width G implies cell(G,i,j) = { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof assume that A1: 1 <= i & i < len G and A2: 1 <= j & j < width G; A3: cell(G,i,j) = v_strip(G,i) /\ h_strip(G,j) by GOBOARD5:def 3; A4: v_strip(G,i) = { |[r,s]| : G*(i,1)`1 <= r & r <= G* (i+1,1)`1 } by A1,Th20; A5: h_strip(G,j) = { |[r,s]| : G*(1,j)`2 <= s & s <= G* (1,j+1)`2 } by A2,Th23; thus cell(G,i,j) c= { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 } proof let x be set; assume A6: x in cell(G,i,j); then x in v_strip(G,i) by A3,XBOOLE_0:def 3; then consider r1,s1 such that A7: x = |[r1,s1]| and A8: G*(i,1)`1 <= r1 & r1 <= G*(i+1,1)`1 by A4; x in h_strip(G,j) by A3,A6,XBOOLE_0:def 3; then consider r2,s2 such that A9: x = |[r2,s2]| and A10: G*(1,j)`2 <= s2 & s2 <= G*(1,j+1)`2 by A5; r1 = r2 & s1 = s2 by A7,A9,SPPOL_2:1; hence thesis by A7,A8,A10; end; let x be set; assume x in { |[r,s]| : G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 }; then ex r,s st x = |[r,s]| & G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2; then x in v_strip(G,i) & x in h_strip(G,j) by A4,A5; hence thesis by A3,XBOOLE_0:def 3; end; theorem Th33: for G being Matrix of TOP-REAL 2 holds cell(G,i,j) is closed proof let G be Matrix of TOP-REAL 2; A1:cell(G,i,j)=h_strip(G,j) /\ v_strip(G,i) by GOBOARD5:def 3; A2:h_strip(G,j) is closed by Th16; v_strip(G,i) is closed by Th17; hence cell(G,i,j) is closed by A1,A2,TOPS_1:35; end; theorem Th34: for G being non empty-yielding Matrix of TOP-REAL 2 holds 1<=len G & 1<=width G proof let G be non empty-yielding Matrix of TOP-REAL 2; not(len G=0 or width G=0) by GOBOARD1:def 5; hence thesis by RLVECT_1:99; end; theorem for G being Go-board holds i<=len G & j<=width G implies cell(G,i,j)=Cl Int cell(G,i,j) proof let G be Go-board; assume A1:i<=len G & j<=width G; set Y = Int cell(G,i,j); Y c= cell(G,i,j) by TOPS_1:44; then A2: Cl Y c= Cl cell(G,i,j) by PRE_TOPC:49; cell(G,i,j) is closed by Th33; then A3: Cl Y c= cell(G,i,j) by A2,PRE_TOPC:52; cell(G,i,j) c= Cl Y proof let x;assume A4:x in cell(G,i,j); then reconsider p=x as Point of TOP-REAL 2; for G0 being Subset of TOP-REAL 2 st G0 is open holds p in G0 implies Y meets G0 proof let G0 be Subset of TOP-REAL 2; assume A5:G0 is open; now assume A6:p in G0; reconsider u=p as Point of Euclid 2 by SPPOL_1:17; reconsider v=u as Element of REAL 2 by SPPOL_1:18; TOP-REAL 2=TopSpaceMetr(Euclid 2) by EUCLID:def 8; then consider r be real number such that A7:r>0 & Ball(u,r) c= G0 by A5,A6,TOPMETR:22; reconsider r as Real by XREAL_0:def 1; i>=0 by NAT_1:18; then A8: i=0 or 0+1<=i by NAT_1:38; j>=0 by NAT_1:18; then A9: j=0 or 0+1<=j by NAT_1:38; now per cases by A1,A8,A9,REAL_1:def 5; case A10:i=0 & j=0; then p in { |[r2,s2]| : r2 <= G*(1,1)`1 & s2 <= G*(1,1)`2 } by A4,Th24; then consider r2,s2 such that A11: p=|[r2,s2]| &( r2 <= G*(1,1)`1 & s2 <= G*(1,1)`2); set r3=r2-r/2 ,s3=s2-r/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A12:p`1=r2 & p`2=s2 by A11,EUCLID:56; A13:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A14:r/2>0 by XCMPLX_0:def 9; then r3<r3+r/2 by REAL_1:69; then r3<r2 by XCMPLX_1:27; then A15:r3<G*(1,1)`1 by A11,AXIOMS:22; s3<s3+r/2 by A14,REAL_1:69; then s3<s2 by XCMPLX_1:27; then A16:s3<G*(1,1)`2 by A11,AXIOMS:22; A17:r2-r3 =r/2 by XCMPLX_1:18; A18:s2-s3=r/2 by XCMPLX_1:18; A19:r/2*sqrt 2>=0 by A14,Lm1,REAL_2:121; A20:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2by SQUARE_1:68; A21:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A22: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A19,A20,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then (Pitag_dist 2).(v,v0)<r by A12,A13,A17,A18,A22,TOPREAL3:12; then A23:u0 in Ball(u,r) by A21,METRIC_1:12; u0 in { |[r1,s1]| : r1 < G*(1,1)`1 & s1 < G* (1,1)`2 } by A15,A16; then u0 in Y by A10,GOBOARD6:21; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A23,XBOOLE_0:def 3; case A24:i=0 & j=width G; then p in { |[r2,s2]| : r2 <= G*(1,1)`1 & G*(1,width G)`2 <=s2 } by A4,Th25; then consider r2,s2 such that A25: p=|[r2,s2]| &( r2 <= G*(1,1)`1 & G*(1,width G)`2<=s2); set r3=r2-r/2,s3=s2+r/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A26:p`1=r2 & p`2=s2 by A25,EUCLID:56; A27:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A28:r/2>0 by XCMPLX_0:def 9; then r3<r3+r/2 by REAL_1:69; then r3<r2 by XCMPLX_1:27; then A29:r3<G*(1,1)`1 by A25,AXIOMS:22; s3>s2 by A28,REAL_1:69; then A30:s3>G*(1,width G)`2 by A25,AXIOMS:22; A31:r2-r3=r/2 by XCMPLX_1:18; A32:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-r/2 by XCMPLX_1:26; A33:r/2*sqrt 2>=0 by A28,Lm1,REAL_2:121; A34:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2by SQUARE_1:68; A35:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A36: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A33,A34,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A31,A32,A36,SQUARE_1:61 ; then dist(u,u0) < r by A26,A27,A35,TOPREAL3:12; then A37:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 < G*(1,1)`1 & G*(1,width G)`2<s1 } by A29,A30; then u0 in Y & u0 in G0 by A7,A24,A37,GOBOARD6:22; hence Y /\ G0 <> {}(TOP-REAL 2) by XBOOLE_0:def 3; case A38:i=0 & 1<=j & j<width G; then p in { |[r2,s2]| : r2 <= G*(1,1)`1 & G*(1,j)`2 <=s2 & s2<=G*(1,j+1)`2} by A4,Th26; then consider r2,s2 such that A39: p=|[r2,s2]| &( r2 <= G*(1,1)`1 & G*(1,j)`2 <=s2 & s2<=G*(1,j+1)`2); now per cases by A39,REAL_1:def 5; case A40:s2=G*(1,j)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rm=min(r,rl); A41: rm<=r & rm<=rl by SQUARE_1:35; A42:j<j+1 by NAT_1:38;A43:j+1<=width G by A38,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A38,A42,A43,GOBOARD5:5; then A44:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A45:rm/2>0 by REAL_2:127; A46:rl/2>0 by A44,REAL_2:127; A47:rm/2<=rl/2 by A41,REAL_1:73; rm/2<=r/2 by A41,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A45,SQUARE_1:77; then A48:(r/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(rm/2)^2 by REAL_1:55; then A49: sqrt((r/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2) by A48,SQUARE_1:94; set r3=r2-r/2 ,s3=s2+rm/2; set q0=|[r3,s3]|; A50:p`1=r2 & p`2=s2 by A39,EUCLID:56; A51:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A52:r/2>0 by XCMPLX_0:def 9; then r3<r3+r/2 by REAL_1:69; then r3<r2 by XCMPLX_1:27; then A53:r3<G*(1,1)`1 by A39,AXIOMS:22; s3>s2 by A45,REAL_1:69; then A54:s3>G*(1,j)`2 by A39,AXIOMS:22; A55:G*(1,j)`2+rm/2<=G*(1,j)`2+rl/2 by A47,AXIOMS:24; A56:G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 <G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 by A46,REAL_1:69; G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j)`2+((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:1 .=G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j+1)`2 by XCMPLX_1:27; then A57:s3<G*(1,j+1)`2 by A40,A55,A56,AXIOMS:22; A58:r2-r3=r/2 by XCMPLX_1:18; A59:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-rm/2 by XCMPLX_1:26; A60:r/2*sqrt 2>=0 by A52,Lm1,REAL_2:121; A61:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2by SQUARE_1:68; A62:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A63: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A60,A61,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r/2)^2 + (rm/2)^2)<r by A49,A63,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A58,A59,SQUARE_1:61; then dist(u,u0) < r by A50,A51,A62,TOPREAL3:12; then A64:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 < G*(1,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A53,A54,A57; then u0 in Y by A38,GOBOARD6:23; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A64,XBOOLE_0:def 3; case A65:(G*(1,j)`2 <s2 & s2<G*(1,j+1)`2); set r3=r2-r/2,s3=s2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A66:p`1=r2 & p`2=s2 by A39,EUCLID:56; A67:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A68:r/2>0 by XCMPLX_0:def 9; then r3<r3+r/2 by REAL_1:69; then r3<r2 by XCMPLX_1:27; then A69:r3<G*(1,1)`1 by A39,AXIOMS:22; A70:r2-r3=r/2 by XCMPLX_1:18; A71:s2-s3=0 by XCMPLX_1:14; A72:(r/2)^2 >=0 by SQUARE_1:72; A73:r/2*sqrt 2>=0 by A68,Lm1,REAL_2:121; A74:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A75:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A76: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A77: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A73,A74,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; (r/2)^2 + 0 <=(r/2)^2 + (r/2)^2 by A72,AXIOMS:24; then sqrt((r/2)^2 + 0^2)<=sqrt((r/2)^2 + (r/2)^2) by A72,SQUARE_1:60,94; then sqrt((r2 - r3)^2 + (s2 - s3)^2)<r by A70,A71,A76,A77,AXIOMS :22; then dist(u,u0) < r by A66,A67,A75,TOPREAL3:12; then A78:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 < G*(1,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A65,A69; then u0 in Y by A38,GOBOARD6:23; hence Y /\ G0 <> {} by A7,A78,XBOOLE_0:def 3; case A79:s2=G*(1,j+1)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rm=min(r,rl); A80: rm<=r & rm<=rl by SQUARE_1:35; A81:j<j+1 by NAT_1:38;A82:j+1<=width G by A38,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A38,A81,A82,GOBOARD5:5; then A83:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A84:rm/2>0 by REAL_2:127; A85:rl/2>0 by A83,REAL_2:127; A86:rm/2<=rl/2 by A80,REAL_1:73; rm/2<=r/2 by A80,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A84,SQUARE_1:77; then A87:(r/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(rm/2)^2 by REAL_1:55; then A88: sqrt((r/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2) by A87,SQUARE_1:94; set r3=r2-r/2,s3=s2-rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A89:p`1=r2 & p`2=s2 by A39,EUCLID:56; A90:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A91:r/2>0 by XCMPLX_0:def 9; then r3<r3+r/2 by REAL_1:69; then r3<r2 by XCMPLX_1:27; then A92:r3<G*(1,1)`1 by A39,AXIOMS:22; s3<s3+rm/2 by A84,REAL_1:69; then s3<s2 by XCMPLX_1:27; then A93:s3<G*(1,j+1)`2 by A39,AXIOMS:22; A94:G*(1,j+1)`2-rm/2>=G*(1,j+1)`2-rl/2 by A86,REAL_2:106; A95:G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 >G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 by A85,SQUARE_1:29; G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j+1)`2-((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:36 .=G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j)`2 by XCMPLX_1:18; then A96:s3>G*(1,j)`2 by A79,A94,A95,AXIOMS:22; A97:r2-r3=r/2 by XCMPLX_1:18; A98:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-((s2+-rm/2)-s2) by XCMPLX_0:def 8 .=--rm/2 by XCMPLX_1:26 .=rm/2; A99:r/2*sqrt 2>=0 by A91,Lm1,REAL_2:121; A100:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A101:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A102: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A99,A100,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A88,A97,A98,A102,AXIOMS:22; then dist(u,u0) < r by A89,A90,A101,TOPREAL3:12; then A103:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 < G*(1,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A92,A93,A96; then u0 in Y by A38,GOBOARD6:23; hence Y /\ G0 <> {} by A7,A103,XBOOLE_0:def 3; end; hence Y /\ G0 <> {}(TOP-REAL 2); case A104:i=len G & j=0; then p in { |[r2,s2]| : r2 >= G*(len G,1)`1 & G*(1,1)`2 >=s2 } by A4,Th27; then consider r2,s2 such that A105: p=|[r2,s2]| &( r2 >= G*(len G,1)`1 & G*(1,1)`2>=s2); set r3=r2+r/2,s3=s2-r/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A106:p`1=r2 & p`2=s2 by A105,EUCLID:56; A107:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A108:r/2>0 by XCMPLX_0:def 9; then s3<s3+r/2 by REAL_1:69; then s3<s2 by XCMPLX_1:27; then A109:s3<G*(1,1)`2 by A105,AXIOMS:22; r3>r2 by A108,REAL_1:69; then A110:r3>G*(len G,1)`1 by A105,AXIOMS:22; A111:s2-s3=r/2 by XCMPLX_1:18; A112:r2-r3=-(r3-r2) by XCMPLX_1:143 .=-r/2 by XCMPLX_1:26; A113:r/2*sqrt 2>=0 by A108,Lm1,REAL_2:121; A114:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A115:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A116: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A113,A114,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A111,A112,A116,SQUARE_1 :61; then dist(u,u0) < r by A106,A107,A115,TOPREAL3:12; then A117:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 > G*(len G,1)`1 & G*(1,1)`2>s1 } by A109,A110; then u0 in Y by A104,GOBOARD6:24; hence Y /\ G0 <> {} by A7,A117,XBOOLE_0:def 3; case A118:i=len G & j=width G; then p in { |[r2,s2]| : G*(len G,1)`1<=r2 & G*(1,width G)`2<= s2 } by A4,Th28; then consider r2,s2 such that A119: p=|[r2,s2]| &( G*(len G,1)`1<=r2 & G*(1,width G)`2<=s2); set r3=r2+r/2,s3=s2+r/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A120:p`1=r2 & p`2=s2 by A119,EUCLID:56; A121:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A122:r/2>0 by XCMPLX_0:def 9; then r2<r2+r/2 by REAL_1:69; then A123:r3>G*(len G,1)`1 by A119,AXIOMS:22; s2<s2+r/2 by A122,REAL_1:69; then A124:s3>G*(1,width G)`2 by A119,AXIOMS:22; A125:r2-r3=r2-r2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A126:s2-s3=s2-s2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A127:r/2*sqrt 2>=0 by A122,Lm1,REAL_2:121; A128:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A129:(-r/2)^2=(r/2)^2 by SQUARE_1:61; A130:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A131: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A127,A128,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then dist(u,u0) < r by A120,A121,A125,A126,A129,A130,A131,TOPREAL3:12; then A132:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 > G*(len G,1)`1 & s1 > G*(1,width G)`2 } by A123,A124; then u0 in Y by A118,GOBOARD6:25; hence Y /\ G0 <> {} by A7,A132,XBOOLE_0:def 3; case A133:i=len G & 1<=j & j<width G; then p in { |[r2,s2]| : r2 >= G*(len G,1)`1 & G*(1,j)`2 <=s2 & s2<=G*(1,j+1)`2} by A4,Th29; then consider r2,s2 such that A134: p=|[r2,s2]| &( r2 >= G*(len G,1)`1 & G*(1,j)`2 <=s2 & s2<=G*(1,j+1)`2); now per cases by A134,REAL_1:def 5; case A135:s2=G*(1,j)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rm=min(r,rl); A136: rm<=r & rm<=rl by SQUARE_1:35; A137:j<j+1 by NAT_1:38;A138:j+1<=width G by A133,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A133,A137,A138,GOBOARD5:5; then A139:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A140:rm/2>0 by REAL_2:127; A141:rl/2>0 by A139,REAL_2:127; A142:rm/2<=rl/2 by A136,REAL_1:73; rm/2<=r/2 by A136,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A140,SQUARE_1:77; then A143:(r/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(rm/2)^2 by REAL_1:55; then A144: sqrt((r/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A143,SQUARE_1:94; set r3=r2+r/2 ,s3=s2+rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A145:p`1=r2 & p`2=s2 by A134,EUCLID:56; A146:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A147:r/2>0 by XCMPLX_0:def 9; then r2<r2+r/2 by REAL_1:69; then A148:r3>G*(len G,1)`1 by A134,AXIOMS:22; s3>s2 by A140,REAL_1:69; then A149:s3>G*(1,j)`2 by A134,AXIOMS:22; A150:G*(1,j)`2+rm/2<=G*(1,j)`2+rl/2 by A142,AXIOMS:24; A151:G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 <G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 by A141,REAL_1:69; G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j)`2+((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:1 .=G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j+1)`2 by XCMPLX_1:27; then A152:s3<G*(1,j+1)`2 by A135,A150,A151,AXIOMS:22; A153:r2-r3=r2-r2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A154:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-rm/2 by XCMPLX_1:26; A155:r/2*sqrt 2>=0 by A147,Lm1,REAL_2:121; A156:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A157:(-r/2)^2=(r/2)^2 by SQUARE_1:61; A158:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A159: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A155,A156,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r/2)^2 + (rm/2)^2)<r by A144,A159,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A153,A154,A157, SQUARE_1:61; then dist(u,u0) < r by A145,A146,A158,TOPREAL3:12; then A160:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 > G*(len G,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A148,A149,A152; then u0 in Y by A133,GOBOARD6:26; hence Y /\ G0 <> {} by A7,A160,XBOOLE_0:def 3; case A161:(G*(1,j)`2 <s2 & s2<G*(1,j+1)`2); set r3=r2+r/2,s3=s2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A162:p`1=r2 & p`2=s2 by A134,EUCLID:56; A163:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A164:r/2>0 by XCMPLX_0:def 9; then r2<r2+r/2 by REAL_1:69; then A165:r3>G*(len G,1)`1 by A134,AXIOMS:22; A166:r2-r3=r2-r2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A167:s2-s3=0 by XCMPLX_1:14; A168:(r/2)^2 >=0 by SQUARE_1:72; A169:r/2*sqrt 2>=0 by A164,Lm1,REAL_2:121; A170:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A171:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A172: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A173: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A169,A170,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; (r/2)^2 + 0 <=(r/2)^2 + (r/2)^2 by A168,AXIOMS:24; then sqrt((r/2)^2 + 0^2)<=sqrt((r/2)^2 + (r/2)^2) by A168,SQUARE_1:60,94; then sqrt((r/2)^2 + 0^2)<r by A172,A173,AXIOMS:22; then sqrt((r2 - r3)^2 + (s2 - s3)^2)<r by A166,A167,SQUARE_1:61 ; then dist(u,u0) < r by A162,A163,A171,TOPREAL3:12; then A174:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 > G*(len G,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A161,A165; then u0 in Y by A133,GOBOARD6:26; hence Y /\ G0 <> {} by A7,A174,XBOOLE_0:def 3; case A175:s2=G*(1,j+1)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rm=min(r,rl); A176: rm<=r & rm<=rl by SQUARE_1:35; A177:j<j+1 by NAT_1:38;A178:j+1<=width G by A133,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A133,A177,A178,GOBOARD5:5; then A179:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A180:rm/2>0 by REAL_2:127; A181:rl/2>0 by A179,REAL_2:127; A182:rm/2<=rl/2 by A176,REAL_1:73; rm/2<=r/2 by A176,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A180,SQUARE_1:77; then A183:(r/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(rm/2)^2 by REAL_1:55; then A184: sqrt((r/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A183,SQUARE_1:94; set r3=r2+r/2,s3=s2-rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A185:p`1=r2 & p`2=s2 by A134,EUCLID:56; A186:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A187:r/2>0 by XCMPLX_0:def 9; then r2<r2+r/2 by REAL_1:69; then A188:r3>G*(len G,1)`1 by A134,AXIOMS:22; s3<s3+rm/2 by A180,REAL_1:69; then s3<s2 by XCMPLX_1:27; then A189:s3<G*(1,j+1)`2 by A134,AXIOMS:22; A190:G*(1,j+1)`2-rm/2>=G*(1,j+1)`2-rl/2 by A182,REAL_2:106; A191:G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 >G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 by A181,SQUARE_1:29; G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j+1)`2-((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:36 .=G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j)`2 by XCMPLX_1:18; then A192:s3>G*(1,j)`2 by A175,A190,A191,AXIOMS:22; A193:r2-r3=r2-r2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A194:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-((s2+-rm/2)-s2) by XCMPLX_0:def 8 .=--rm/2 by XCMPLX_1:26 .=rm/2; A195:r/2*sqrt 2>=0 by A187,Lm1,REAL_2:121; A196:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A197:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A198: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A195,A196,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r/2)^2 + (rm/2)^2)<r by A184,A198,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A193,A194,SQUARE_1:61 ; then dist(u,u0) < r by A185,A186,A197,TOPREAL3:12; then A199:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : r1 > G*(len G,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A188,A189,A192; then u0 in Y by A133,GOBOARD6:26; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A199,XBOOLE_0:def 3; end; hence Y /\ G0 <> {}(TOP-REAL 2); case A200:1<=i & i<len G & j=0; then p in { |[r2,s2]| : G*(i,1)`1 <=r2 & r2<=G*(i+1,1)`1 & s2 <= G*(1,1)`2 } by A4,Th30; then consider r2,s2 such that A201: p=|[r2,s2]| &( G*(i,1)`1 <=r2 & r2<=G*(i+1,1)`1 & s2 <= G*(1,1)`2); now per cases by A201,REAL_1:def 5; case A202:r2=G*(i,1)`1; set sl=G*(i+1,1)`1 - G*(i,1)`1; set sm=min(r,sl); A203: sm<=r & sm<=sl by SQUARE_1:35; A204:i<i+1 by NAT_1:38;A205:i+1<=len G by A200,NAT_1:38; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A200,A204,A205,GOBOARD5:4; then A206:sl>0 by SQUARE_1:11; then sm>0 by A7,SPPOL_1:13; then A207:sm/2>0 by REAL_2:127; A208:sl/2>0 by A206,REAL_2:127; A209:sm/2<=sl/2 by A203,REAL_1:73; sm/2<=r/2 by A203,REAL_1:73; then (sm/2)^2<=(r/2)^2 by A207,SQUARE_1:77; then A210:(r/2)^2+(sm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(sm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(sm/2)^2 by REAL_1:55; then A211: sqrt((r/2)^2+(sm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A210,SQUARE_1:94; set s3=s2-r/2,r3=r2+sm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A212:p`1=r2 & p`2=s2 by A201,EUCLID:56; A213:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A214:r/2>0 by XCMPLX_0:def 9; then s3<s3+r/2 by REAL_1:69; then s3<s2 by XCMPLX_1:27; then A215:s3<G*(1,1)`2 by A201,AXIOMS:22; r3>r2 by A207,REAL_1:69; then A216:r3>G*(i,1)`1 by A201,AXIOMS:22; A217:G*(i,1)`1+sm/2<=G*(i,1)`1+sl/2 by A209,AXIOMS:24; A218:G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 <G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 by A208,REAL_1:69; G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i,1)`1+((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:1 .=G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i+1,1)`1 by XCMPLX_1:27; then A219:r3<G*(i+1,1)`1 by A202,A217,A218,AXIOMS:22; A220:s2-s3=r/2 by XCMPLX_1:18; A221:r2-r3=-(r3-r2) by XCMPLX_1:143 .=-sm/2 by XCMPLX_1:26; A222:r/2*sqrt 2>=0 by A214,Lm1,REAL_2:121; A223:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A224:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A225: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A222,A223,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r/2)^2 + (sm/2)^2)<r by A211,A225,AXIOMS:22; then sqrt ((p`1 - q0`1)^2 + (p`2 - q0`2)^2)<r by A212,A213,A220,A221,SQUARE_1:61; then dist(u,u0) < r by A224,TOPREAL3:12; then A226:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & s1 < G*(1,1)`2} by A215,A216,A219; then u0 in Y by A200,GOBOARD6:27; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A226,XBOOLE_0:def 3; case A227:(G*(i,1)`1 <r2 & r2<G*(i+1,1)`1); set s3=s2-r/2,r3=r2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A228:p`1=r2 & p`2=s2 by A201,EUCLID:56; A229:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A230:r/2>0 by XCMPLX_0:def 9; then s3<s3+r/2 by REAL_1:69; then s3<s2 by XCMPLX_1:27; then A231:s3<G*(1,1)`2 by A201,AXIOMS:22; A232:s2-s3=r/2 by XCMPLX_1:18; A233:r2-r3=0 by XCMPLX_1:14; A234:(r/2)^2 >=0 by SQUARE_1:72; A235:r/2*sqrt 2>=0 by A230,Lm1,REAL_2:121; A236:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A237:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A238: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A239: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A235,A236,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; 0^2 + (r/2)^2 <=(r/2)^2 + (r/2)^2 by A234,AXIOMS:24,SQUARE_1:60 ; then sqrt(0^2 + (r/2)^2 )<=sqrt((r/2)^2 + (r/2)^2) by A234,SQUARE_1:60,94; then sqrt((r2 - r3)^2 + (s2 - s3)^2 )<r by A232,A233,A238,A239,AXIOMS:22; then dist(u,u0) < r by A228,A229,A237,TOPREAL3:12; then A240:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & s1 < G*(1,1)`2 } by A227,A231; then u0 in Y by A200,GOBOARD6:27; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A240,XBOOLE_0:def 3; case A241:r2=G*(i+1,1)`1; set sl=G*(i+1,1)`1 - G*(i,1)`1; set sm=min(r,sl); A242: sm<=r & sm<=sl by SQUARE_1:35; A243:i<i+1 by NAT_1:38;A244:i+1<=len G by A200,NAT_1:38; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A200,A243,A244,GOBOARD5:4; then A245:sl>0 by SQUARE_1:11; then sm>0 by A7,SPPOL_1:13; then A246:sm/2>0 by REAL_2:127; A247:sl/2>0 by A245,REAL_2:127; A248:sm/2<=sl/2 by A242,REAL_1:73; sm/2<=r/2 by A242,REAL_1:73; then (sm/2)^2<=(r/2)^2 by A246,SQUARE_1:77; then A249:(r/2)^2+(sm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(sm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(sm/2)^2 by REAL_1:55; then A250: sqrt((r/2)^2+(sm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A249,SQUARE_1:94; set s3=s2-r/2,r3=r2-sm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A251:p`1=r2 & p`2=s2 by A201,EUCLID:56; A252:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A253:r/2>0 by XCMPLX_0:def 9; then s3<s3+r/2 by REAL_1:69; then s3<s2 by XCMPLX_1:27; then A254:s3<G*(1,1)`2 by A201,AXIOMS:22; r3<r3+sm/2 by A246,REAL_1:69; then r3<r2 by XCMPLX_1:27; then A255:r3<G*(i+1,1)`1 by A201,AXIOMS:22; A256:G*(i+1,1)`1-sm/2>=G*(i+1,1)`1-sl/2 by A248,REAL_2:106; A257:G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 >G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 by A247,SQUARE_1:29; G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i+1,1)`1-((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:36 .=G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i,1)`1 by XCMPLX_1:18; then A258:r3>G*(i,1)`1 by A241,A256,A257,AXIOMS:22; A259:s2-s3=r/2 by XCMPLX_1:18; A260:r2-r3=-(r3-r2) by XCMPLX_1:143 .=-((r2+-sm/2)-r2) by XCMPLX_0:def 8 .=--sm/2 by XCMPLX_1:26 .=sm/2; A261:r/2*sqrt 2>=0 by A253,Lm1,REAL_2:121; A262:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A263:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A264: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A261,A262,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((p`1 - q0`1)^2 + (p`2 - q0`2)^2)<r by A250,A251,A252,A259,A260,A264,AXIOMS:22; then dist(u,u0) < r by A263,TOPREAL3:12; then A265:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & s1 < G*(1,1)`2 } by A254,A255,A258; then u0 in Y by A200,GOBOARD6:27; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A265,XBOOLE_0:def 3; end; hence Y /\ G0 <> {}(TOP-REAL 2); case A266:1<=i & i<len G & j=width G; then p in { |[r2,s2]| : G*(i,1)`1 <=r2 & r2<=G*(i+1,1)`1 & s2>=G*(1,width G)`2} by A4,Th31; then consider r2,s2 such that A267: p=|[r2,s2]| &( G*(i,1)`1 <=r2 & r2<=G*(i+1,1)`1 & s2>=G*(1,width G)`2); now per cases by A267,REAL_1:def 5; case A268:r2=G*(i,1)`1; set rl=G*(i+1,1)`1 - G*(i,1)`1; set rm=min(r,rl); A269: rm<=r & rm<=rl by SQUARE_1:35; A270:i<i+1 by NAT_1:38;A271:i+1<=len G by A266,NAT_1:38; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A266,A270,A271,GOBOARD5:4; then A272:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A273:rm/2>0 by REAL_2:127; A274:rl/2>0 by A272,REAL_2:127; A275:rm/2<=rl/2 by A269,REAL_1:73; rm/2<=r/2 by A269,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A273,SQUARE_1:77; then A276:(r/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(rm/2)^2 by REAL_1:55; then A277: sqrt((r/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A276,SQUARE_1:94; set s3=s2+r/2,r3=r2+rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A278:p`1=r2 & p`2=s2 by A267,EUCLID:56; A279:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A280:r/2>0 by XCMPLX_0:def 9; then s2<s2+r/2 by REAL_1:69; then A281:s3>G*(1,width G)`2 by A267,AXIOMS:22; r3>r2 by A273,REAL_1:69; then A282:r3>G*(i,1)`1 by A267,AXIOMS:22; A283:G*(i,1)`1+rm/2<=G*(i,1)`1+rl/2 by A275,AXIOMS:24; A284:G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 <G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 by A274,REAL_1:69; G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i,1)`1+((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:1 .=G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i+1,1)`1 by XCMPLX_1:27; then A285:r3<G*(i+1,1)`1 by A268,A283,A284,AXIOMS:22; A286:s2-s3=s2-s2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A287:r2-r3=-(r3-r2) by XCMPLX_1:143 .=-rm/2 by XCMPLX_1:26; A288:r/2*sqrt 2>=0 by A280,Lm1,REAL_2:121; A289:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A290:(-r/2)^2=(r/2)^2 by SQUARE_1:61; A291:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A292: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A288,A289,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((rm/2)^2+(r/2)^2 )<r by A277,A292,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A286,A287,A290, SQUARE_1:61; then dist(u,u0) < r by A278,A279,A291,TOPREAL3:12; then A293:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & s1 > G*(1,width G)`2 } by A281,A282,A285; then u0 in Y by A266,GOBOARD6:28; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A293,XBOOLE_0:def 3; case A294:(G*(i,1)`1 <r2 & r2<G*(i+1,1)`1); set s3=s2+r/2,r3=r2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A295:p`1=r2 & p`2=s2 by A267,EUCLID:56; A296:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A297:r/2>0 by XCMPLX_0:def 9; then s2<s3 by REAL_1:69; then A298:s3>G*(1,width G)`2 by A267,AXIOMS:22; A299:s2-s3=s2-s2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A300:r2-r3=0 by XCMPLX_1:14; A301:(r/2)^2 >=0 by SQUARE_1:72; A302:r/2*sqrt 2>=0 by A297,Lm1,REAL_2:121; A303:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A304:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A305: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A306: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A302,A303,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; (r/2)^2 + 0^2 <=(r/2)^2 + (r/2)^2 by A301,AXIOMS:24,SQUARE_1:60 ; then sqrt((r/2)^2 + 0^2)<=sqrt((r/2)^2 + (r/2)^2) by A301,SQUARE_1:60,94; then sqrt((r/2)^2 + 0^2)<r by A305,A306,AXIOMS:22; then sqrt((r2 - r3)^2 + (s2 - s3)^2)<r by A299,A300,SQUARE_1:61 ; then dist(u,u0) < r by A295,A296,A304,TOPREAL3:12; then A307:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & s1 > G*(1,width G)`2 } by A294,A298; then u0 in Y by A266,GOBOARD6:28; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A307,XBOOLE_0:def 3; case A308:r2=G*(i+1,1)`1; set rl=G*(i+1,1)`1 - G*(i,1)`1; set rm=min(r,rl); A309: rm<=r & rm<=rl by SQUARE_1:35; A310:i<i+1 by NAT_1:38;A311:i+1<=len G by A266,NAT_1:38; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A266,A310,A311,GOBOARD5:4; then A312:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A313:rm/2>0 by REAL_2:127; A314:rl/2>0 by A312,REAL_2:127; A315:rm/2<=rl/2 by A309,REAL_1:73; rm/2<=r/2 by A309,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A313,SQUARE_1:77; then A316:(r/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=(r/2)^2 by SQUARE_1:72; then 0+0<=(r/2)^2+(rm/2)^2 by REAL_1:55; then A317: sqrt((r/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A316,SQUARE_1:94; set s3=s2+r/2,r3=r2-rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A318:p`1=r2 & p`2=s2 by A267,EUCLID:56; A319:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A320:r/2>0 by XCMPLX_0:def 9; then s3>s2 by REAL_1:69; then A321:s3>G*(1,width G)`2 by A267,AXIOMS:22; r3<r3+rm/2 by A313,REAL_1:69; then r3<r2 by XCMPLX_1:27; then A322:r3<G*(i+1,1)`1 by A267,AXIOMS:22; A323:G*(i+1,1)`1-rm/2>=G*(i+1,1)`1-rl/2 by A315,REAL_2:106; A324:G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 >G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 by A314,SQUARE_1:29; G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i+1,1)`1-((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:36 .=G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i,1)`1 by XCMPLX_1:18; then A325:r3>G*(i,1)`1 by A308,A323,A324,AXIOMS:22; A326:s2-s3=s2-s2-r/2 by XCMPLX_1:36 .=0-r/2 by XCMPLX_1:14 .=-r/2 by XCMPLX_1:150; A327:r2-r3=-(r3-r2) by XCMPLX_1:143 .=-((r2+-rm/2)-r2) by XCMPLX_0:def 8 .=--rm/2 by XCMPLX_1:26 .=rm/2; A328:r/2*sqrt 2>=0 by A320,Lm1,REAL_2:121; A329:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A330:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A331: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A328,A329,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r/2)^2 + (rm/2)^2)<r by A317,A331,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A326,A327,SQUARE_1:61 ; then dist(u,u0) < r by A318,A319,A330,TOPREAL3:12; then A332:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & s1 > G*(1,width G)`2} by A321,A322,A325; then u0 in Y by A266,GOBOARD6:28; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A332,XBOOLE_0:def 3; end; hence Y /\ G0 <> {}(TOP-REAL 2); case A333:1<=i & i<len G & 1<=j & j<width G; then p in { |[r2,s2]| : G*(i,1)`1 <=r2 & r2<=G*(i+1,1)`1 & G*(1,j)`2 <=s2 & s2<=G*(1,j+1)`2} by A4,Th32; then consider r2,s2 such that A334: p=|[r2,s2]| &( G*(i,1)`1 <=r2 & r2<=G*(i+1,1)`1 & G*(1,j)`2 <=s2 & s2<=G*(1,j+1)`2); now per cases by A334,REAL_1:def 5; case A335:r2=G*(i,1)`1 & s2=G*(1,j)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rl1=G*(i+1,1)`1 - G*(i,1)`1; set rm=min(r,rl); set rm1=min(r,rl1); A336: rm<=r & rm<=rl by SQUARE_1:35; A337: rm1<=r & rm1<=rl1 by SQUARE_1:35; A338:j<j+1 by NAT_1:38;A339:j+1<=width G by A333,NAT_1:38; A340:i<i+1 by NAT_1:38;A341:i+1<=len G by A333,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A333,A338,A339,GOBOARD5:5; then A342:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A343:rm/2>0 by REAL_2:127; A344:rl/2>0 by A342,REAL_2:127; A345:rm/2<=rl/2 by A336,REAL_1:73; rm/2<=r/2 by A336,REAL_1:73; then A346: (rm/2)^2<=(r/2)^2 by A343,SQUARE_1:77; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A333,A340,A341,GOBOARD5:4; then A347:rl1>0 by SQUARE_1:11; then rm1>0 by A7,SPPOL_1:13; then A348:rm1/2>0 by REAL_2:127; A349:rl1/2>0 by A347,REAL_2:127; A350:rm1/2<=rl1/2 by A337,REAL_1:73; rm1/2<=r/2 by A337,REAL_1:73; then (rm1/2)^2<=(r/2)^2 by A348,SQUARE_1:77; then A351:(rm1/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by A346,REAL_1:55; 0<=(rm/2)^2 & 0<=(rm1/2)^2 by SQUARE_1:72; then 0+0<=(rm1/2)^2+(rm/2)^2 by REAL_1:55; then A352: sqrt((rm1/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A351,SQUARE_1:94; set r3=r2+rm1/2,s3=s2+rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A353:p`1=r2 & p`2=s2 by A334,EUCLID:56; A354:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A355:r/2>0 by XCMPLX_0:def 9; s3>s2 by A343,REAL_1:69; then A356:s3>G*(1,j)`2 by A334,AXIOMS:22; A357:G*(1,j)`2+rm/2<=G*(1,j)`2+rl/2 by A345,AXIOMS:24; A358:G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 <G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 by A344,REAL_1:69; G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j)`2+((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:1 .=G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j+1)`2 by XCMPLX_1:27; then A359:s3<G*(1,j+1)`2 by A335,A357,A358,AXIOMS:22; r3>r2 by A348,REAL_1:69; then A360:r3>G*(i,1)`1 by A334,AXIOMS:22; A361:G*(i,1)`1+rm1/2<=G*(i,1)`1+rl1/2 by A350,AXIOMS:24; A362:G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 <G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 by A349,REAL_1:69; G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i,1)`1+((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:1 .=G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i+1,1)`1 by XCMPLX_1:27; then A363:r3<G*(i+1,1)`1 by A335,A361,A362,AXIOMS:22; A364:r2-r3= -(r3-r2) by XCMPLX_1:143 .=-rm1/2 by XCMPLX_1:26; A365:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-rm/2 by XCMPLX_1:26; A366:r/2*sqrt 2>=0 by A355,Lm1,REAL_2:121; A367:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A368:(-rm1/2)^2=(rm1/2)^2 by SQUARE_1:61; A369:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A370: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A366,A367,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((rm1/2)^2 + (rm/2)^2)<r by A352,A370,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A364,A365,A368, SQUARE_1:61; then dist(u,u0) < r by A353,A354,A369,TOPREAL3:12; then A371:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G*(1,j+1)`2 } by A356,A359,A360,A363; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A371,XBOOLE_0:def 3; case A372: r2=G*(i,1)`1 &(G*(1,j)`2 <s2 & s2<G*(1,j+1)`2); set rl1=G*(i+1,1)`1 - G*(i,1)`1; set rm1=min(r,rl1); A373: rm1<=r & rm1<=rl1 by SQUARE_1:35; A374:i<i+1 by NAT_1:38;A375:i+1<=len G by A333,NAT_1:38; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A333,A374,A375,GOBOARD5:4; then A376:rl1>0 by SQUARE_1:11; then rm1>0 by A7,SPPOL_1:13; then A377:rm1/2>0 by REAL_2:127; A378:rl1/2>0 by A376,REAL_2:127; A379:rm1/2<=rl1/2 by A373,REAL_1:73; rm1/2<=r/2 by A373,REAL_1:73; then (rm1/2)^2<=(r/2)^2 by A377,SQUARE_1:77; then A380:(rm1/2)^2+0^2<=(r/2)^2+0^2 by REAL_1:55; 0<=(rm1/2)^2 & 0<=0^2 by SQUARE_1:72; then 0+0<=(rm1/2)^2+0^2 by REAL_1:55; then A381: sqrt((rm1/2)^2+0^2)<=sqrt((r/2)^2+0^2) by A380, SQUARE_1:94; set r3=r2+rm1/2; set s3=s2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A382:p`1=r2 & p`2=s2 by A334,EUCLID:56; A383:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A384:r/2>0 by XCMPLX_0:def 9; A385: r3>r2 by A377,REAL_1:69; A386:G*(i,1)`1+rm1/2<=G*(i,1)`1+rl1/2 by A379,AXIOMS:24; A387:G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 <G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 by A378,REAL_1:69; G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i,1)`1+((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:1 .=G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i+1,1)`1 by XCMPLX_1:27; then A388:r3<G*(i+1,1)`1 by A372,A386,A387,AXIOMS:22; A389:r2-r3= -(r3-r2) by XCMPLX_1:143 .=-rm1/2 by XCMPLX_1:26; A390:s2-s3=0 by XCMPLX_1:14; A391:(r/2)^2 >=0 by SQUARE_1:72; A392:r/2*sqrt 2>=0 by A384,Lm1,REAL_2:121; A393:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A394:(-rm1/2)^2=(rm1/2)^2 by SQUARE_1:61; A395:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A396: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A397: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A392,A393,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; (r/2)^2 + 0^2 <=(r/2)^2 + (r/2)^2 by A391,AXIOMS:24,SQUARE_1:60 ; then sqrt((r/2)^2 + 0^2)<=sqrt((r/2)^2 + (r/2)^2) by A391,SQUARE_1:60,94; then sqrt((r/2)^2 + 0^2)<r by A396,A397,AXIOMS:22; then sqrt((r2 - r3)^2 + (s2 - s3)^2)<r by A381,A389,A390,A394,AXIOMS:22; then dist(u,u0) < r by A382,A383,A395,TOPREAL3:12; then A398:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G*(1,j+1)`2 } by A372,A385,A388; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A398,XBOOLE_0:def 3; case A399:r2=G*(i,1)`1 & s2=G*(1,j+1)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rl1=G*(i+1,1)`1 - G*(i,1)`1; set rm=min(r,rl); set rm1=min(r,rl1); A400: rm<=r & rm<=rl by SQUARE_1:35; A401: rm1<=r & rm1<=rl1 by SQUARE_1:35; A402:j<j+1 by NAT_1:38;A403:j+1<=width G by A333,NAT_1:38; A404:i<i+1 by NAT_1:38;A405:i+1<=len G by A333,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A333,A402,A403,GOBOARD5:5; then A406:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A407:rm/2>0 by REAL_2:127; A408:rl/2>0 by A406,REAL_2:127; A409:rm/2<=rl/2 by A400,REAL_1:73; rm/2<=r/2 by A400,REAL_1:73; then A410: (rm/2)^2<=(r/2)^2 by A407,SQUARE_1:77; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A333,A404,A405,GOBOARD5:4; then A411:rl1>0 by SQUARE_1:11; then rm1>0 by A7,SPPOL_1:13; then A412:rm1/2>0 by REAL_2:127; A413:rl1/2>0 by A411,REAL_2:127; A414:rm1/2<=rl1/2 by A401,REAL_1:73; rm1/2<=r/2 by A401,REAL_1:73; then (rm1/2)^2<=(r/2)^2 by A412,SQUARE_1:77; then A415:(rm1/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by A410,REAL_1:55; 0<=(rm/2)^2 & 0<=(rm1/2)^2 by SQUARE_1:72; then 0+0<=(rm1/2)^2+(rm/2)^2 by REAL_1:55; then A416: sqrt((rm1/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A415,SQUARE_1:94; set r3=r2+rm1/2,s3=s2-rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A417:p`1=r2 & p`2=s2 by A334,EUCLID:56; A418:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A419:r/2>0 by XCMPLX_0:def 9; s3<s2 by A407,SQUARE_1:29; then A420:s3<G*(1,j+1)`2 by A334,AXIOMS:22; A421:G*(1,j+1)`2-rm/2>=G*(1,j+1)`2-rl/2 by A409,REAL_1:92; A422:G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 >G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 by A408,SQUARE_1:29; G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j+1)`2-((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:36 .=G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j)`2 by XCMPLX_1:18; then A423:s3>G*(1,j)`2 by A399,A421,A422,AXIOMS:22; r3>r2 by A412,REAL_1:69; then A424:r3>G*(i,1)`1 by A334,AXIOMS:22; A425:G*(i,1)`1+rm1/2<=G*(i,1)`1+rl1/2 by A414,AXIOMS:24; A426:G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 <G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 by A413,REAL_1:69; G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i,1)`1+((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:1 .=G*(i,1)`1+(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i+1,1)`1 by XCMPLX_1:27; then A427:r3<G*(i+1,1)`1 by A399,A425,A426,AXIOMS:22; A428:r2-r3= -(r3-r2) by XCMPLX_1:143 .=-rm1/2 by XCMPLX_1:26; A429:s2-s3=rm/2 by XCMPLX_1:18; A430:r/2*sqrt 2>=0 by A419,Lm1,REAL_2:121; A431:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A432:(-rm1/2)^2=(rm1/2)^2 by SQUARE_1:61; A433:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A434: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A430,A431,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A416,A428,A429,A432,A434,AXIOMS:22; then dist(u,u0) < r by A417,A418,A433,TOPREAL3:12; then A435:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G*(1,j+1)`2 } by A420,A423,A424,A427; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A435,XBOOLE_0:def 3; case A436:(G*(i,1)`1 <r2 & r2<G*(i+1,1)`1)& s2=G*(1,j)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rm=min(r,rl); A437: rm<=r & rm<=rl by SQUARE_1:35; A438:j<j+1 by NAT_1:38;A439:j+1<=width G by A333,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A333,A438,A439,GOBOARD5:5; then A440:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A441:rm/2>0 by REAL_2:127; A442:rl/2>0 by A440,REAL_2:127; A443:rm/2<=rl/2 by A437,REAL_1:73; rm/2<=r/2 by A437,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A441,SQUARE_1:77; then A444:(rm/2)^2+0^2<=(r/2)^2+0^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=0^2 by SQUARE_1:72; then 0+0<=(rm/2)^2+0^2 by REAL_1:55; then A445: sqrt(0^2+(rm/2)^2)<=sqrt(0^2+(r/2)^2) by A444,SQUARE_1 :94; set s3=s2+rm/2; set r3=r2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A446:p`1=r2 & p`2=s2 by A334,EUCLID:56; A447:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A448:r/2>0 by XCMPLX_0:def 9; A449: s3>s2 by A441,REAL_1:69; A450:G*(1,j)`2+rm/2<=G*(1,j)`2+rl/2 by A443,AXIOMS:24; A451:G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 <G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 by A442,REAL_1:69; G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j)`2+((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:1 .=G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j+1)`2 by XCMPLX_1:27; then A452:s3<G*(1,j+1)`2 by A436,A450,A451,AXIOMS:22; A453:s2-s3= -(s3-s2) by XCMPLX_1:143 .=-rm/2 by XCMPLX_1:26; A454:r2-r3=0 by XCMPLX_1:14; A455:(r/2)^2 >=0 by SQUARE_1:72; A456:r/2*sqrt 2>=0 by A448,Lm1,REAL_2:121; A457:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A458:(-rm/2)^2=(rm/2)^2 by SQUARE_1:61; A459:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A460: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A461: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A456,A457,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; 0^2+(r/2)^2 <=(r/2)^2 + (r/2)^2 by A455,AXIOMS:24,SQUARE_1:60; then sqrt(0^2+(r/2)^2 )<=sqrt((r/2)^2 + (r/2)^2) by A455,SQUARE_1:60,94; then sqrt(0^2+(r/2)^2)<r by A460,A461,AXIOMS:22; then sqrt((r2 - r3)^2 + (s2 - s3)^2)<r by A445,A453,A454,A458,AXIOMS:22; then dist(u,u0) < r by A446,A447,A459,TOPREAL3:12; then A462:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G*(1,j+1)`2 } by A436,A449,A452; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A462,XBOOLE_0:def 3; case A463:(G*(i,1)`1 <r2 & r2<G*(i+1,1)`1) &(G*(1,j)`2 <s2 & s2<G*(1,j+1)`2); set s3=s2,r3=r2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A464:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A465:r/2>0 by XCMPLX_0:def 9; A466:s2-s3=0 by XCMPLX_1:14; A467:r2-r3=0 by XCMPLX_1:14; A468:(r/2)^2 >=0 by SQUARE_1:72; A469:r/2*sqrt 2>=0 by A465,Lm1,REAL_2:121; A470:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A471:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A472: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A473: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A469,A470,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; 0^2 + 0^2 <=(r/2)^2 + (r/2)^2 by A468,REAL_1:55,SQUARE_1:60; then sqrt(0^2 + 0^2)<=sqrt((r/2)^2 + (r/2)^2 ) by SQUARE_1:60,94; then sqrt((r2 - r3)^2 + (s2 - s3)^2 )<r by A466,A467,A472,A473,AXIOMS:22; then dist(u,u0) < r by A334,A464,A471,TOPREAL3:12; then A474:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1<r1 & r1<G*(i+1,1)`1 & G*(1,j)`2<s1 & s1<G*(1,j+1)`2} by A463; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A474,XBOOLE_0:def 3; case A475:(G*(i,1)`1 <r2 & r2<G*(i+1,1)`1) & s2=G*(1,j+1)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rm=min(r,rl); A476: rm<=r & rm<=rl by SQUARE_1:35; A477:j<j+1 by NAT_1:38;A478:j+1<=width G by A333,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A333,A477,A478,GOBOARD5:5; then A479:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A480:rm/2>0 by REAL_2:127; A481:rl/2>0 by A479,REAL_2:127; A482:rm/2<=rl/2 by A476,REAL_1:73; rm/2<=r/2 by A476,REAL_1:73; then (rm/2)^2<=(r/2)^2 by A480,SQUARE_1:77; then A483:(rm/2)^2+0^2<=(r/2)^2+0^2 by REAL_1:55; 0<=(rm/2)^2 & 0<=0^2 by SQUARE_1:72; then 0+0<=(rm/2)^2+0^2 by REAL_1:55; then A484: sqrt(0^2+(rm/2)^2)<=sqrt(0^2+(r/2)^2) by A483,SQUARE_1 :94; set s3=s2-rm/2; set r3=r2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A485:p`1=r2 & p`2=s2 by A334,EUCLID:56; A486:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A487:r/2>0 by XCMPLX_0:def 9; A488: s3<s2 by A480,SQUARE_1:29; A489:G*(1,j+1)`2-rm/2>=G*(1,j+1)`2-rl/2 by A482,REAL_1:92; A490:G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 >G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 by A481,SQUARE_1:29; G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j+1)`2-((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:36 .=G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j)`2 by XCMPLX_1:18; then A491:s3>G*(1,j)`2 by A475,A489,A490,AXIOMS:22; A492:s2-s3=rm/2 by XCMPLX_1:18; A493:r2-r3=0 by XCMPLX_1:14; A494:(r/2)^2 >=0 by SQUARE_1:72; A495:r/2*sqrt 2>=0 by A487,Lm1,REAL_2:121; A496:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A497:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A498: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A499: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A495,A496,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; 0+(r/2)^2 <=(r/2)^2 + (r/2)^2 by A494,AXIOMS:24; then sqrt(0^2+(r/2)^2 )<=sqrt((r/2)^2 + (r/2)^2) by A494,SQUARE_1:60,94; then sqrt(0^2+(r/2)^2)<r by A498,A499,AXIOMS:22; then sqrt((r2 - r3)^2 + (s2 - s3)^2 )<r by A484,A492,A493,AXIOMS:22; then dist(u,u0) < r by A485,A486,A497,TOPREAL3:12; then A500:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G* (1,j+1)`2 } by A475,A488,A491; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A500,XBOOLE_0:def 3; case A501:r2=G*(i+1,1)`1 & s2=G*(1,j)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rl1=G*(i+1,1)`1 - G*(i,1)`1; set rm=min(r,rl); set rm1=min(r,rl1); A502: rm<=r & rm<=rl by SQUARE_1:35; A503: rm1<=r & rm1<=rl1 by SQUARE_1:35; A504:j<j+1 by NAT_1:38;A505:j+1<=width G by A333,NAT_1:38; A506:i<i+1 by NAT_1:38;A507:i+1<=len G by A333,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A333,A504,A505,GOBOARD5:5; then A508:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A509:rm/2>0 by REAL_2:127; A510:rl/2>0 by A508,REAL_2:127; A511:rm/2<=rl/2 by A502,REAL_1:73; rm/2<=r/2 by A502,REAL_1:73; then A512: (rm/2)^2<=(r/2)^2 by A509,SQUARE_1:77; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A333,A506,A507,GOBOARD5:4; then A513:rl1>0 by SQUARE_1:11; then rm1>0 by A7,SPPOL_1:13; then A514:rm1/2>0 by REAL_2:127; A515:rl1/2>0 by A513,REAL_2:127; A516:rm1/2<=rl1/2 by A503,REAL_1:73; rm1/2<=r/2 by A503,REAL_1:73; then (rm1/2)^2<=(r/2)^2 by A514,SQUARE_1:77; then A517:(rm1/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by A512,REAL_1:55; 0<=(rm/2)^2 & 0<=(rm1/2)^2 by SQUARE_1:72; then 0+0<=(rm1/2)^2+(rm/2)^2 by REAL_1:55; then A518: sqrt((rm1/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A517,SQUARE_1:94; set r3=r2-rm1/2,s3=s2+rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A519:p`1=r2 & p`2=s2 by A334,EUCLID:56; A520:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A521:r/2>0 by XCMPLX_0:def 9; s3>s2 by A509,REAL_1:69; then A522:s3>G*(1,j)`2 by A334,AXIOMS:22; A523:G*(1,j)`2+rm/2<=G*(1,j)`2+rl/2 by A511,AXIOMS:24; A524:G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 <G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 by A510,REAL_1:69; G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j)`2+((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:1 .=G*(1,j)`2+(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j+1)`2 by XCMPLX_1:27; then A525:s3<G*(1,j+1)`2 by A501,A523,A524,AXIOMS:22; r3<r2 by A514,SQUARE_1:29; then A526:r3<G*(i+1,1)`1 by A334,AXIOMS:22; A527:G*(i+1,1)`1-rm1/2>=G*(i+1,1)`1-rl1/2 by A516,REAL_1:92; A528:G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 >G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 by A515,SQUARE_1:29; G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i+1,1)`1-((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:36 .=G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i,1)`1 by XCMPLX_1:18; then A529:r3>G*(i,1)`1 by A501,A527,A528,AXIOMS:22; A530:r2-r3=rm1/2 by XCMPLX_1:18; A531:s2-s3=-(s3-s2) by XCMPLX_1:143 .=-rm/2 by XCMPLX_1:26; A532:r/2*sqrt 2>=0 by A521,Lm1,REAL_2:121; A533:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A534:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A535: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A532,A533,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((rm1/2)^2 + (rm/2)^2)<r by A518,A535,AXIOMS:22; then sqrt ((r2 - r3)^2 + (s2 - s3)^2)<r by A530,A531,SQUARE_1:61 ; then dist(u,u0) < r by A519,A520,A534,TOPREAL3:12; then A536:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G*(1,j+1)`2 } by A522,A525,A526,A529; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A536,XBOOLE_0:def 3; case A537:r2=G*(i+1,1)`1 &(G*(1,j)`2 <s2 & s2<G*(1,j+1)`2); set rl1=G*(i+1,1)`1 - G*(i,1)`1; set rm1=min(r,rl1); A538: rm1<=r & rm1<=rl1 by SQUARE_1:35; A539:i<i+1 by NAT_1:38;A540:i+1<=len G by A333,NAT_1:38; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A333,A539,A540,GOBOARD5:4; then A541:rl1>0 by SQUARE_1:11; then rm1>0 by A7,SPPOL_1:13; then A542:rm1/2>0 by REAL_2:127; A543:rl1/2>0 by A541,REAL_2:127; A544:rm1/2<=rl1/2 by A538,REAL_1:73; rm1/2<=r/2 by A538,REAL_1:73; then (rm1/2)^2<=(r/2)^2 by A542,SQUARE_1:77; then A545:0^2+(rm1/2)^2<=0^2+(r/2)^2 by REAL_1:55; 0<=(rm1/2)^2 & 0<=0^2 by SQUARE_1:72; then 0+0<=0^2+(rm1/2)^2 by REAL_1:55; then A546: sqrt((rm1/2)^2+0^2)<=sqrt((r/2)^2+0^2) by A545, SQUARE_1:94; set r3=r2-rm1/2; set s3=s2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A547:p`1=r2 & p`2=s2 by A334,EUCLID:56; A548:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A549:r/2>0 by XCMPLX_0:def 9; A550: r3<r2 by A542,SQUARE_1:29; A551:G*(i+1,1)`1-rm1/2>=G*(i+1,1)`1-rl1/2 by A544,REAL_1:92; A552:G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 >G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 by A543,SQUARE_1:29; G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i+1,1)`1-((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:36 .=G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i,1)`1 by XCMPLX_1:18; then A553:r3>G*(i,1)`1 by A537,A551,A552,AXIOMS:22; A554:r2-r3=rm1/2 by XCMPLX_1:18; A555:s2-s3=0 by XCMPLX_1:14; A556:(r/2)^2 >=0 by SQUARE_1:72; A557:r/2*sqrt 2>=0 by A549,Lm1,REAL_2:121; A558:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A559:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A560: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; A561: sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A557,A558,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; (r/2)^2+0 <=(r/2)^2 + (r/2)^2 by A556,AXIOMS:24; then sqrt((r/2)^2+0^2 )<=sqrt((r/2)^2 + (r/2)^2) by A556,SQUARE_1:60,94; then sqrt((r/2)^2+0^2)<r by A560,A561,AXIOMS:22; then sqrt((r2 - r3)^2 + (s2 - s3)^2 )<r by A546,A554,A555,AXIOMS:22; then dist(u,u0) < r by A547,A548,A559,TOPREAL3:12; then A562:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G* (1,j+1)`2 } by A537,A550,A553; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A562,XBOOLE_0:def 3; case A563: r2=G*(i+1,1)`1 & s2=G*(1,j+1)`2; set rl=G*(1,j+1)`2 - G*(1,j)`2; set rl1=G*(i+1,1)`1 - G*(i,1)`1; set rm=min(r,rl); set rm1=min(r,rl1); A564: rm<=r & rm<=rl by SQUARE_1:35; A565: rm1<=r & rm1<=rl1 by SQUARE_1:35; A566:j<j+1 by NAT_1:38;A567:j+1<=width G by A333,NAT_1:38; A568:i<i+1 by NAT_1:38;A569:i+1<=len G by A333,NAT_1:38; 1<=len G by Th34; then G*(1,j)`2<G*(1,j+1)`2 by A333,A566,A567,GOBOARD5:5; then A570:rl>0 by SQUARE_1:11; then rm>0 by A7,SPPOL_1:13; then A571:rm/2>0 by REAL_2:127; A572:rl/2>0 by A570,REAL_2:127; A573:rm/2<=rl/2 by A564,REAL_1:73; rm/2<=r/2 by A564,REAL_1:73; then A574: (rm/2)^2<=(r/2)^2 by A571,SQUARE_1:77; 1<=width G by Th34; then G*(i,1)`1<G*(i+1,1)`1 by A333,A568,A569,GOBOARD5:4; then A575:rl1>0 by SQUARE_1:11; then rm1>0 by A7,SPPOL_1:13; then A576:rm1/2>0 by REAL_2:127; A577:rl1/2>0 by A575,REAL_2:127; A578:rm1/2<=rl1/2 by A565,REAL_1:73; rm1/2<=r/2 by A565,REAL_1:73; then (rm1/2)^2<=(r/2)^2 by A576,SQUARE_1:77; then A579:(rm1/2)^2+(rm/2)^2<=(r/2)^2+(r/2)^2 by A574,REAL_1:55; 0<=(rm/2)^2 & 0<=(rm1/2)^2 by SQUARE_1:72; then 0+0<=(rm1/2)^2+(rm/2)^2 by REAL_1:55; then A580: sqrt((rm1/2)^2+(rm/2)^2)<=sqrt((r/2)^2+(r/2)^2 ) by A579,SQUARE_1:94; set r3=r2-rm1/2,s3=s2-rm/2; reconsider q0=|[r3,s3]| as Point of TOP-REAL 2; A581:p`1=r2 & p`2=s2 by A334,EUCLID:56; A582:q0`1=r3 & q0`2=s3 by EUCLID:56; reconsider u0=q0 as Point of Euclid 2 by SPPOL_1:17; reconsider v0=u0 as Element of REAL 2 by SPPOL_1:18; r*2">0 by A7,REAL_2:122; then A583:r/2>0 by XCMPLX_0:def 9; s3<s2 by A571,SQUARE_1:29; then A584:s3<G*(1,j+1)`2 by A334,AXIOMS:22; A585:G*(1,j+1)`2-rm/2>=G*(1,j+1)`2-rl/2 by A573,REAL_1:92; A586:G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 >G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 by A572,SQUARE_1:29; G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2)/2 -(G*(1,j+1)`2-G*(1,j)`2)/2 = G*(1,j+1)`2-((G*(1,j+1)`2-G*(1,j)`2)/2 +(G*(1,j+1)`2-G*(1,j)`2)/2) by XCMPLX_1:36 .=G*(1,j+1)`2-(G*(1,j+1)`2-G*(1,j)`2) by XCMPLX_1:66 .=G*(1,j)`2 by XCMPLX_1:18; then A587:s3>G*(1,j)`2 by A563,A585,A586,AXIOMS:22; r3<r2 by A576,SQUARE_1:29; then A588:r3<G*(i+1,1)`1 by A334,AXIOMS:22; A589:G*(i+1,1)`1-rm1/2>=G*(i+1,1)`1-rl1/2 by A578,REAL_1:92; A590:G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 >G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 by A577,SQUARE_1:29; G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1)/2 -(G*(i+1,1)`1-G*(i,1)`1)/2 = G*(i+1,1)`1-((G*(i+1,1)`1-G*(i,1)`1)/2 +(G*(i+1,1)`1-G*(i,1)`1)/2) by XCMPLX_1:36 .=G*(i+1,1)`1-(G*(i+1,1)`1-G*(i,1)`1) by XCMPLX_1:66 .=G*(i,1)`1 by XCMPLX_1:18; then A591:r3>G*(i,1)`1 by A563,A589,A590,AXIOMS:22; A592:r2-r3=rm1/2 by XCMPLX_1:18; A593:s2-s3=rm/2 by XCMPLX_1:18; A594:r/2*sqrt 2>=0 by A583,Lm1,REAL_2:121; A595:(r/2)^2 + (r/2)^2= 2*((r/2)^2) by XCMPLX_1:11 .=(sqrt 2)^2*((r/2)^2) by SQUARE_1:def 4 .=(r/2*sqrt 2)^2 by SQUARE_1:68; A596:dist(u,u0) = (Pitag_dist 2).(v,v0) by Lm11,METRIC_1:def 1; sqrt 2/2<1 by Lm1,REAL_2:142,SQUARE_1:86; then A597: r*(sqrt 2/2)<r*1 by A7,REAL_1:70; sqrt ((r/2)^2 + (r/2)^2) = r/2*sqrt 2 by A594,A595,SQUARE_1:89 .= sqrt 2*r/2 by XCMPLX_1:75 .=r*((sqrt 2)/2) by XCMPLX_1:75; then sqrt ((rm1/2)^2 + (rm/2)^2)<r by A580,A597,AXIOMS:22; then dist(u,u0) < r by A581,A582,A592,A593,A596,TOPREAL3:12; then A598:u0 in Ball(u,r) by METRIC_1:12; u0 in { |[r1,s1]| : G*(i,1)`1 < r1 & r1 < G*(i+1,1)`1 & G*(1,j)`2 < s1 & s1 < G*(1,j+1)`2 } by A584,A587,A588,A591; then u0 in Y by A333,GOBOARD6:29; hence Y /\ G0 <> {}(TOP-REAL 2) by A7,A598,XBOOLE_0:def 3; end; hence Y /\ G0 <> {}(TOP-REAL 2); end; hence Y /\ G0 <> {}(TOP-REAL 2); end; hence p in G0 implies Y meets G0 by XBOOLE_0:def 7; end; hence x in Cl Y by PRE_TOPC:def 13; end; hence thesis by A3,XBOOLE_0:def 10; end;