The Mizar article:

Properties of the External Approximation of Jordan's Curve

by
Artur Kornilowicz

Received June 24, 1999

Copyright (c) 1999 Association of Mizar Users

MML identifier: JORDAN10
[ MML identifier index ]


environ

 vocabulary RELAT_2, COMPTS_1, SPPOL_1, EUCLID, TOPREAL1, FINSEQ_1, JORDAN9,
      MATRIX_1, JORDAN8, GOBOARD1, GOBOARD5, TREES_1, BOOLE, ARYTM_1, TARSKI,
      PSCOMP_1, ARYTM_3, GROUP_1, MCART_1, PRE_TOPC, GOBOARD9, TOPS_1,
      SUBSET_1, CONNSP_1, RELAT_1, JORDAN2C, LATTICES, CONNSP_3, SETFAM_1,
      TOPREAL4, PCOMPS_1, WEIERSTR, METRIC_1, JORDAN10, FINSEQ_4;
 notation TARSKI, XBOOLE_0, SUBSET_1, SETFAM_1, XREAL_0, REAL_1, NAT_1,
      BINARITH, STRUCT_0, METRIC_1, TBSP_1, FINSEQ_1, NEWTON, FINSEQ_4,
      WEIERSTR, PRE_TOPC, TOPS_1, CONNSP_1, CONNSP_3, COMPTS_1, PCOMPS_1,
      MATRIX_1, EUCLID, TOPREAL1, GOBOARD1, GOBOARD5, TOPREAL4, PSCOMP_1,
      GOBOARD9, SPPOL_1, JORDAN2C, JORDAN8, GOBRD13, GOBRD14, JORDAN9;
 constructors BINARITH, CARD_4, CONNSP_1, CONNSP_3, FINSEQ_4, GOBOARD9,
      GOBRD13, GOBRD14, JORDAN2C, JORDAN8, JORDAN9, PSCOMP_1, REAL_1, REALSET1,
      TBSP_1, TOPREAL4, TOPS_1, WEIERSTR, JORDAN1;
 clusters XREAL_0, BORSUK_2, EUCLID, GOBRD14, JORDAN8, PCOMPS_1, PRE_TOPC,
      PSCOMP_1, RELSET_1, SPPOL_2, SPRECT_1, STRUCT_0, TOPREAL6, SUBSET_1,
      FINSEQ_1, ARYTM_3, SPRECT_4, JORDAN2C, MEMBERED;
 requirements REAL, NUMERALS, SUBSET, BOOLE, ARITHM;
 definitions TARSKI, XBOOLE_0;
 theorems AXIOMS, BINARITH, CONNSP_1, CONNSP_3, EUCLID, GOBOARD5, GOBOARD6,
      GOBOARD7, GOBOARD9, GOBRD11, GOBRD13, GOBRD14, HEINE, JGRAPH_1, JORDAN1,
      JORDAN2C, JORDAN3, JORDAN6, JORDAN8, JORDAN9, NEWTON, NAT_1, PRE_TOPC,
      PSCOMP_1, REAL_1, REAL_2, RLVECT_1, SETFAM_1, SPPOL_1, SPPOL_2, SPRECT_1,
      SPRECT_3, SPRECT_4, SUBSET_1, TARSKI, TOPREAL1, TOPREAL3, TOPREAL4,
      TOPREAL6, TOPS_1, WEIERSTR, ZFMISC_1, XBOOLE_0, XBOOLE_1, SQUARE_1,
      XCMPLX_0, XCMPLX_1;
 schemes NAT_1;

begin  :: Properties of the external approximation of Jordan's curve

definition
 cluster connected compact non vertical non horizontal Subset of TOP-REAL 2;
existence
  proof
    take R^2-unit_square;
    thus thesis;
  end;
end;

reserve i, j, k, n for Nat,
   P for Subset of TOP-REAL 2,
   C for connected compact non vertical non horizontal Subset of TOP-REAL 2;

theorem Th1:
 1 <= k & k+1 <= len Cage(C,n) &
  [i,j] in Indices Gauge(C,n) & [i,j+1] in Indices Gauge(C,n) &
   Cage(C,n)/.k = Gauge(C,n)*(i,j) & Cage(C,n)/.(k+1) = Gauge(C,n)*(i,j+1)
 implies i < len Gauge(C,n)
  proof
    set f = Cage(C,n),
        G = Gauge(C,n);
    assume that
A1:   1 <= k & k+1 <= len Cage(C,n) and
A2:   [i,j] in Indices Gauge(C,n) and
A3:   [i,j+1] in Indices Gauge(C,n) &
      Cage(C,n)/.k = Gauge(C,n)*(i,j) &
      Cage(C,n)/.(k+1) = Gauge(C,n)*(i,j+1);
A4: i <= len G by A2,GOBOARD5:1;
    assume i >= len G;
then A5: i = len G by A4,REAL_1:def 5;
      f is_sequence_on G by JORDAN9:def 1;
then A6: right_cell(f,k,G) = cell(G,i,j) by A1,A2,A3,GOBRD13:23;
      len G = width G by JORDAN8:def 1;
    then j <= len G by A2,GOBOARD5:1;
    then cell(G,len G,j) misses C by JORDAN8:19;
    hence contradiction by A1,A5,A6,JORDAN9:33;
  end;

theorem Th2:
 1 <= k & k+1 <= len Cage(C,n) &
  [i,j] in Indices Gauge(C,n) & [i,j+1] in Indices Gauge(C,n) &
   Cage(C,n)/.k = Gauge(C,n)*(i,j+1) & Cage(C,n)/.(k+1) = Gauge(C,n)*(i,j)
 implies i > 1
  proof
    set f = Cage(C,n),
        G = Gauge(C,n);
    assume that
A1:   1 <= k & k+1 <= len Cage(C,n) and
A2:   [i,j] in Indices Gauge(C,n) and
A3:   [i,j+1] in Indices Gauge(C,n) &
      Cage(C,n)/.k = Gauge(C,n)*(i,j+1) &
      Cage(C,n)/.(k+1) = Gauge(C,n)*(i,j);
A4: 1 <= i by A2,GOBOARD5:1;
    assume i <= 1;
    then i = 1 by A4,REAL_1:def 5;
then A5: i-'1 = 0 by GOBOARD9:1;
      f is_sequence_on G by JORDAN9:def 1;
then A6: right_cell(f,k,G) = cell(G,i-'1,j) by A1,A2,A3,GOBRD13:29;
      len G = width G by JORDAN8:def 1;
    then j <= len G by A2,GOBOARD5:1;
    then cell(G,0,j) misses C by JORDAN8:21;
    hence contradiction by A1,A5,A6,JORDAN9:33;
  end;

theorem Th3:
 1 <= k & k+1 <= len Cage(C,n) &
  [i,j] in Indices Gauge(C,n) & [i+1,j] in Indices Gauge(C,n) &
   Cage(C,n)/.k = Gauge(C,n)*(i,j) & Cage(C,n)/.(k+1) = Gauge(C,n)*(i+1,j)
 implies j > 1
  proof
    set f = Cage(C,n),
        G = Gauge(C,n);
    assume that
A1:   1 <= k & k+1 <= len Cage(C,n) and
A2:   [i,j] in Indices Gauge(C,n) and
A3:   [i+1,j] in Indices Gauge(C,n) &
      Cage(C,n)/.k = Gauge(C,n)*(i,j) &
      Cage(C,n)/.(k+1) = Gauge(C,n)*(i+1,j);
A4: 1 <= j by A2,GOBOARD5:1;
    assume j <= 1;
    then j = 1 by A4,REAL_1:def 5;
then A5: j-'1 = 0 by GOBOARD9:1;
      f is_sequence_on G by JORDAN9:def 1;
then A6: right_cell(f,k,G) = cell(G,i,j-'1) by A1,A2,A3,GOBRD13:25;
      i <= len G by A2,GOBOARD5:1;
    then cell(G,i,0) misses C by JORDAN8:20;
    hence contradiction by A1,A5,A6,JORDAN9:33;
  end;

theorem Th4:
 1 <= k & k+1 <= len Cage(C,n) &
  [i,j] in Indices Gauge(C,n) & [i+1,j] in Indices Gauge(C,n) &
   Cage(C,n)/.k = Gauge(C,n)*(i+1,j) & Cage(C,n)/.(k+1) = Gauge(C,n)*(i,j)
 implies j < width Gauge(C,n)
  proof
    set f = Cage(C,n),
        G = Gauge(C,n);
    assume that
A1:   1 <= k & k+1 <= len Cage(C,n) and
A2:   [i,j] in Indices Gauge(C,n) and
A3:   [i+1,j] in Indices Gauge(C,n) &
      Cage(C,n)/.k = Gauge(C,n)*(i+1,j) &
      Cage(C,n)/.(k+1) = Gauge(C,n)*(i,j);
A4: j <= width G by A2,GOBOARD5:1;
    assume j >= width G;
then A5: j = width G by A4,REAL_1:def 5;
      f is_sequence_on G by JORDAN9:def 1;
then A6: right_cell(f,k,G) = cell(G,i,j) by A1,A2,A3,GOBRD13:27;
A7: len G = width G by JORDAN8:def 1;
      i <= len G by A2,GOBOARD5:1;
    then cell(G,i,len G) misses C by JORDAN8:18;
    hence contradiction by A1,A5,A6,A7,JORDAN9:33;
  end;

theorem Th5:
 C misses L~Cage(C,n)
  proof
    set f = Cage(C,n),
        G = Gauge(C,n);
    assume not thesis;
    then consider c being set such that
A1: c in C & c in L~f by XBOOLE_0:3;
  L~f = union { LSeg(f,i) where i is Nat: 1 <= i & i+1 <= len f }
      by TOPREAL1:def 6;
    then consider Z being set such that
A2:   c in Z and
A3:   Z in { LSeg(f,i) where i is Nat: 1 <= i & i+1 <= len f }
        by A1,TARSKI:def 4;
    consider i being Nat such that
A4:   Z = LSeg(f,i) and
A5:   1 <= i & i+1 <= len f by A3;
      f is_sequence_on G by JORDAN9:def 1;
    then LSeg(f,i) = left_cell(f,i,G) /\ right_cell(f,i,G) by A5,GOBRD13:30;
then A6: c in left_cell(f,i,G) by A2,A4,XBOOLE_0:def 3;
      left_cell(f,i,G) misses C by A5,JORDAN9:33;
    hence contradiction by A1,A6,XBOOLE_0:3;
  end;

theorem Th6:
 N-bound L~Cage(C,n) = N-bound C + (N-bound C - S-bound C)/(2|^n)
  proof
    set a = N-bound C, s = S-bound C, w = W-bound C,
        f = Cage(C,n), G = Gauge(C,n);
    consider i such that
A1:   1 <= i & i+1 <= len G and
A2:   f/.1 = G*(i,width G) and
        f/.2 = G*(i+1,width G) &
      N-min C in cell(G,i,width G-'1) &
      N-min C <> G*(i,width G-'1) by JORDAN9:def 1;
A3: len G = width G by JORDAN8:def 1;
      i+0 <= i+1 by AXIOMS:24;
then A4: i <= len G by A1,AXIOMS:22;
      4 <= len G by JORDAN8:13;
    then 1 <= len G by AXIOMS:22;
then A5: [i,len G] in Indices G by A1,A3,A4,GOBOARD7:10;
A6: 2|^n <> 0 by HEINE:5;
    thus N-bound L~f = (N-min L~f)`2 by PSCOMP_1:94
      .= (f/.1)`2 by JORDAN9:34
      .= |[w+((E-bound C-w)/(2|^n))*(i-2), s+((a-s)/(2|^n))*(len G-2)]|`2
          by A2,A3,A5,JORDAN8:def 1
      .= s+((a-s)/(2|^n))*(len G-2) by EUCLID:56
      .= s+((a-s)/(2|^n))*(2|^n+3-2) by JORDAN8:def 1
      .= s+((a-s)/(2|^n))*(2|^n+(3-2)) by XCMPLX_1:29
      .= s+(((a-s)/(2|^n))*2|^n+((a-s)/(2|^n))*1) by XCMPLX_1:8
      .= s+((a-s)/(2|^n))*2|^n+(a-s)/(2|^n) by XCMPLX_1:1
      .= s+(a-s)+(a-s)/(2|^n) by A6,XCMPLX_1:88
      .= a+(a-s)/(2|^n) by XCMPLX_1:27;
  end;

theorem Th7:
 i < j implies N-bound L~Cage(C,j) < N-bound L~Cage(C,i)
  proof
    assume
A1:   i < j;
defpred P[Nat] means
 i < $1 implies N-bound L~Cage(C,$1) < N-bound L~Cage(C,i);
A2: P[0] by NAT_1:18;
A3: for n being Nat st P[n] holds P[n+1]
    proof
      let n be Nat;
      assume
A4:     P[n];
      assume i < n+1;
then A5:   i <= n by NAT_1:38;
      set j = n + 1,
          a = N-bound C, s = S-bound C;
A6:   N-bound L~Cage(C,n) = a+(a-s)/(2|^n) &
       N-bound L~Cage(C,j) = a+(a-s)/(2|^j) by Th6;
     2|^n > 0 by HEINE:5;
then A7:   2|^n*2 > 0 * 2 by REAL_1:70;
        s < a by SPRECT_1:34;
then A8:   s - a < 0 by REAL_2:105;
        a+(a-s)/(2|^j) - (a+(a-s)/(2|^n))
        = a + (a-s)/(2|^j) - a - (a-s)/(2|^n) by XCMPLX_1:36
       .= a + (a-s)/(2|^j) +- a - (a-s)/(2|^n) by XCMPLX_0:def 8
       .= a +-a + (a-s)/(2|^j) - (a-s)/(2|^n) by XCMPLX_1:1
       .= 0 + (a-s)/(2|^j) - (a-s)/(2|^n) by XCMPLX_0:def 6
       .= (a-s)/(2|^n*2) - (a-s)/(2|^n)/(2/2) by NEWTON:11
       .= (a-s)/(2|^n*2) - (a-s)*2/(2|^n*2) by XCMPLX_1:85
       .= (a-s - (a-s)*2)/(2|^n*2) by XCMPLX_1:121
       .= (a-s - (2*a-2*s))/(2|^n*2) by XCMPLX_1:40
       .= (a-s-2*a+2*s)/(2|^n*2) by XCMPLX_1:37
       .= (a-2*a-s+2*s)/(2|^n*2) by XCMPLX_1:21
       .= (-a-s+2*s)/(2|^n*2) by XCMPLX_1:187
       .= (-a+-s+2*s)/(2|^n*2) by XCMPLX_0:def 8
       .= (-a+(-s+2*s))/(2|^n*2) by XCMPLX_1:1
       .= (-a+s)/(2|^n*2) by XCMPLX_1:184
       .= (s-a)/(2|^n*2) by XCMPLX_0:def 8;
      then 0 > a+(a-s)/(2|^j) - (a+(a-s)/(2|^n)) by A7,A8,REAL_2:128;
      then N-bound L~Cage(C,n+1) < N-bound L~Cage(C,n) by A6,SQUARE_1:12;
      hence thesis by A4,A5,AXIOMS:22,REAL_1:def 5;
    end;
      for n being Nat holds P[n] from Ind(A2,A3);
    hence thesis by A1;
  end;

definition
 let C be connected compact non vertical non horizontal Subset of TOP-REAL 2,
     n be Nat;
 cluster Cl RightComp Cage(C,n) -> compact;
coherence by GOBRD14:42;
end;

theorem Th8:
 N-min C in RightComp Cage(C,n)
  proof
    set f = Cage(C,n),
        G = Gauge(C,n);
A1: N-min C in C by SPRECT_1:13;
      C misses L~f by Th5;
    then C /\ L~f = {} by XBOOLE_0:def 7;
then A2: not N-min C in L~f by A1,XBOOLE_0:def 3;
      RightComp f misses L~f by SPRECT_3:42;
then A3: RightComp f /\ L~f = {} by XBOOLE_0:def 7;
    consider k being Nat such that
A4:   1 <= k & k+1 <= len G and
A5:   f/.1 = G*(k,width G) and
A6:   f/.2 = G*(k+1,width G) and
A7:   N-min C in cell(G,k,width G-'1) and
        N-min C <> G*(k,width G-'1) by JORDAN9:def 1;
A8: f is_sequence_on G by JORDAN9:def 1;
      L~f <> {};
then A9: 1+1 <= len f by GOBRD14:8;
A10: len G = width G by JORDAN8:def 1;
A11: 1 <= k+1 by NAT_1:29;
then A12: 1 <= len G by A4,AXIOMS:22;
A13: k < len G by A4,NAT_1:38;
    then [k,len G] in Indices G & [k+1,len G] in Indices G
      by A4,A10,A11,A12,GOBOARD7:10;
then A14: cell(G,k,len G-'1) = right_cell(f,1,G) by A5,A6,A8,A9,A10,GOBRD13:25;
      right_cell(f,1,G) c= right_cell(f,1) by A8,A9,GOBRD13:34;
then A15: Int right_cell(f,1,G) c= Int right_cell(f,1) by TOPS_1:48;
      Int right_cell(f,1) c= RightComp f by GOBOARD9:def 2;
then A16: Int cell(G,k,len G-'1) c= RightComp f by A14,A15,XBOOLE_1:1;
      RightComp f c= RightComp f \/ L~f by XBOOLE_1:7;
then A17: Int cell(G,k,len G-'1) c= RightComp f \/ L~f by A16,XBOOLE_1:1;
A18: right_cell(f,1,G) is closed by A8,A9,GOBRD13:31;
A19: Fr cell(G,k,len G-'1) c= RightComp f \/ L~f
    proof
      let q be set; assume
A20:   q in Fr cell(G,k,len G-'1);
      then reconsider s = q as Point of TOP-REAL 2;
        4 <= len G by JORDAN8:13;
      then 4 - 1 <= len G - 1 by REAL_1:92;
      then 0 <= len G - 1 by AXIOMS:22;
then A21:   len G-'1 = len G - 1 by BINARITH:def 3;
      A22: len G - 1 < len G - 0 by REAL_1:92;
      then Int cell(G,k,len G-'1) <> {} by A10,A13,A21,GOBOARD9:17;
      then consider p being set such that
A23:     p in Int cell(G,k,len G-'1) by XBOOLE_0:def 1;
      reconsider p as Point of TOP-REAL 2 by A23;
      per cases;
      suppose q in L~f;
      hence thesis by XBOOLE_0:def 2;
      suppose
A24:     not q in L~f;
A25:   LSeg(p,s) c= (L~f)`
      proof
        let a be set; assume
A26:       a in LSeg(p,s);
        then reconsider b = a as Point of TOP-REAL 2;
          3 <= len G-'1 by GOBRD14:17;
then A27:     1 <= len G-'1 by AXIOMS:22;
then A28:     Int cell(G,k,len G-'1) = { |[x,y]| where x, y is Real:
          G*(k,1)`1 < x & x < G*(k+1,1)`1 &
          G*(1,len G-'1)`2 < y & y < G*(1,len G-'1+1)`2 }
            by A4,A10,A13,A21,A22,GOBOARD6:29;
A29:     b = |[b`1,b`2]| by EUCLID:57;
        consider x, y being Real such that
A30:       p = |[x,y]| and
A31:       G*(k,1)`1 < x & x < G*(k+1,1)`1 &
          G*(1,len G-'1)`2 < y & y < G*(1,len G-'1+1)`2 by A23,A28;
          Fr cell(G,k,len G-'1) c= cell(G,k,len G-'1) by A14,A18,TOPS_1:69;
then A32:     q in cell(G,k,len G-'1) by A20;
          cell(G,k,len G-'1) =
          { |[m,o]| where m, o is Real:
            G*(k,1)`1 <= m & m <= G*(k+1,1)`1 &
            G*(1,len G-'1)`2 <= o & o <= G*(1,len G-'1+1)`2 }
              by A4,A10,A13,A21,A22,A27,GOBRD11:32;
        then consider m, o being Real such that
A33:       s = |[m,o]| and
A34:       G*(k,1)`1 <= m & m <= G*(k+1,1)`1 &
          G*(1,len G-'1)`2 <= o & o <= G*(1,len G-'1+1)`2 by A32;
A35:     s`1 = m & s`2 = o & p`1 = x & p`2 = y by A30,A33,EUCLID:56;

          now per cases;
          case b = s;
          hence a in (L~f)` by A24,SUBSET_1:50;
          case
A36:         b <> s;
            now per cases by REAL_1:def 5;
            case s`1 < p`1 & s`2 < p`2;
            then s`1 < b`1 & b`1 <= p`1 & s`2 < b`2 & b`2 <= p`2
              by A26,A36,TOPREAL6:37,38;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 < p`1 & s`2 > p`2;
            then s`1 < b`1 & b`1 <= p`1 & p`2 <= b`2 & b`2 < s`2
              by A26,A36,TOPREAL6:37,38;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 < p`1 & s`2 = p`2;
            then s`1 < b`1 & b`1 <= p`1 & p`2 = b`2 & b`2 = s`2
              by A26,A36,GOBOARD7:6,TOPREAL6:37;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 > p`1 & s`2 < p`2;
            then s`1 > b`1 & b`1 >= p`1 & s`2 < b`2 & b`2 <= p`2
              by A26,A36,TOPREAL6:37,38;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 > p`1 & s`2 > p`2;
            then s`1 > b`1 & b`1 >= p`1 & s`2 > b`2 & b`2 >= p`2
              by A26,A36,TOPREAL6:37,38;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 > p`1 & s`2 = p`2;
            then s`1 > b`1 & b`1 >= p`1 & s`2 = b`2 & b`2 = p`2
              by A26,A36,GOBOARD7:6,TOPREAL6:37;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 = p`1 & s`2 > p`2;
            then s`1 = b`1 & b`1 = p`1 & s`2 > b`2 & b`2 >= p`2
              by A26,A36,GOBOARD7:5,TOPREAL6:38;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 = p`1 & s`2 < p`2;
            then s`1 = b`1 & b`1 = p`1 & s`2 < b`2 & b`2 <= p`2
              by A26,A36,GOBOARD7:5,TOPREAL6:38;
            then G*(k,1)`1 < b`1 & b`1 < G*(k+1,1)`1 &
             G*(1,len G-'1)`2 < b`2 & b`2 < G*(1,len G-'1+1)`2
              by A31,A34,A35,AXIOMS:22;
            hence b in Int cell(G,k,len G-'1) by A28,A29;

            case s`1 = p`1 & s`2 = p`2;
            then p = s by TOPREAL3:11;
            then LSeg(p,s) = {p} by TOPREAL1:7;
            hence b in Int cell(G,k,len G-'1) by A23,A26,TARSKI:def 1;
          end;
          then not b in L~f by A3,A16,XBOOLE_0:def 3;
          hence a in (L~f)` by SUBSET_1:50;
        end;
        hence a in (L~f)`;
      end;
A37:   RightComp f is_a_component_of (L~f)` by GOBOARD9:def 2;
A38:   {p} c= RightComp f by A16,A23,ZFMISC_1:37;
        {p} meets LSeg(p,s)
      proof
          now take a = p;
         thus a in {p} & a in LSeg(p,s) by TARSKI:def 1,TOPREAL1:6;
        end; hence thesis by XBOOLE_0:3;
      end;
then A39:   LSeg(p,s) c= RightComp f by A25,A37,A38,GOBOARD9:6;
        s in LSeg(p,s) by TOPREAL1:6;
      hence thesis by A39,XBOOLE_0:def 2;
    end;
A40: Int right_cell(f,1,G) c= right_cell(f,1,G) by TOPS_1:44;
      Fr right_cell(f,1,G) = right_cell(f,1,G) \ Int right_cell(f,1,G)
      by A18,TOPS_1:77;
    then Fr right_cell(f,1,G) \/ Int right_cell(f,1,G) = right_cell(f,1,G)
      by A40,XBOOLE_1:45;
    then right_cell(f,1,G) c= RightComp f \/ L~f by A14,A17,A19,XBOOLE_1:8;
    hence thesis by A2,A7,A10,A14,XBOOLE_0:def 2;
  end;

theorem Th9:
 C meets RightComp Cage (C,n)
  proof
A1: N-min C in C by SPRECT_1:13;
      N-min C in RightComp Cage(C,n) by Th8;
    then C /\ RightComp Cage (C,n) <> {} by A1,XBOOLE_0:def 3;
    hence thesis by XBOOLE_0:def 7;
  end;

theorem Th10:
 C misses LeftComp Cage(C,n)
  proof
    set f = Cage(C,n);
       C misses L~f by Th5;
then A1:  C /\ L~f = {} by XBOOLE_0:def 7;
A2:  C meets RightComp f by Th9;
    assume A3: C meets LeftComp f;
      LeftComp f is_a_component_of (L~f)` by GOBOARD9:def 1;
    then consider L being Subset of (TOP-REAL 2)|(L~f)` such that
A4:   L = LeftComp f and
A5:   L is_a_component_of (TOP-REAL 2)|(L~f)` by CONNSP_1:def 6;
      RightComp f is_a_component_of (L~f)` by GOBOARD9:def 2;
    then consider R being Subset of (TOP-REAL 2)|(L~f)` such that
A6:   R = RightComp f and
A7:   R is_a_component_of (TOP-REAL 2)|(L~f)` by CONNSP_1:def 6;
      C c= the carrier of (TOP-REAL 2)|(L~f)`
    proof
      let c be set;
      assume c in C;
      then c in the carrier of TOP-REAL 2 & not c in L~f by A1,XBOOLE_0:def 3;
      then c in (L~f)` by SUBSET_1:50;
      hence thesis by JORDAN1:1;
    end;
    then reconsider C1 = C as Subset of (TOP-REAL 2)|(L~f)`;
      C1 is connected by CONNSP_1:24;
    then L = R by A2,A3,A4,A5,A6,A7,JORDAN2C:100;
    hence contradiction by A4,A6,SPRECT_4:7;
  end;

theorem Th11:
 C c= RightComp Cage(C,n)
  proof
    set f = Cage(C,n);
    let c be set;
    assume
A1:   c in C;
      C misses L~f by Th5;
then A2: C /\ L~f = {} by XBOOLE_0:def 7;
      C misses LeftComp f by Th10;
    then C /\ LeftComp f = {} by XBOOLE_0:def 7;
    then not c in LeftComp f & not c in L~f by A1,A2,XBOOLE_0:def 3;
    hence c in RightComp f by A1,GOBRD14:28;
  end;

theorem Th12:
 C c= BDD L~Cage(C,n)
  proof
A1: C c= RightComp Cage(C,n) by Th11;
      RightComp Cage(C,n) is_inside_component_of L~Cage(C,n) by GOBRD14:45;
    then RightComp Cage(C,n) c= BDD L~Cage(C,n) by JORDAN2C:26;
    hence thesis by A1,XBOOLE_1:1;
  end;

theorem Th13:
 UBD L~Cage(C,n) c= UBD C
  proof
    set f = Cage(C,n);
A1: UBD C = union {B where B is Subset of TOP-REAL 2:
      B is_outside_component_of C} by JORDAN2C:def 6;
    let x be set; assume
A2:   x in UBD L~f;
      UBD L~f = union {B where B is Subset of TOP-REAL 2:
     B is_outside_component_of L~f} by JORDAN2C:def 6;
    then consider L being set such that
A3:   x in L and
A4:   L in {B where B is Subset of TOP-REAL 2:
           B is_outside_component_of L~f} by A2,TARSKI:def 4;
    consider B being Subset of TOP-REAL 2 such that
A5:   L = B and
A6:   B is_outside_component_of L~f by A4;
      the carrier of TOP-REAL 2 = the carrier of Euclid 2 by TOPREAL3:13;
    then reconsider B1 = B as Subset of Euclid 2;
      B is_a_component_of (L~f)` by A6,JORDAN2C:def 4;
    then consider B2 being Subset of (TOP-REAL 2)|(L~f)` such that
A7:   B2 = B and
A8:   B2 is_a_component_of (TOP-REAL 2)|(L~f)`
        by CONNSP_1:def 6;
      B2 is connected by A8,CONNSP_1:def 5;
then A9: B is connected by A7,CONNSP_3:34;
      not B is Bounded by A6,JORDAN2C:def 4;
then A10: not B1 is bounded by JORDAN2C:def 2;
      the carrier of (TOP-REAL 2)|C` = C` by JORDAN1:1;
    then skl (Down(B,C`)) c= the carrier of TOP-REAL 2 by XBOOLE_1:1;
    then reconsider P1 = skl (Down(B,C`)) as Subset of TOP-REAL 2;
      RightComp f is_inside_component_of L~f by GOBRD14:45;
then A11: C c= RightComp f & B1 misses RightComp f by A6,Th11,GOBRD14:5;
    then B1 misses C by XBOOLE_1:63;
then A12: P1 is_outside_component_of C by A9,A10,JORDAN2C:71;
A13:   B1 /\ RightComp f = {} by A11,XBOOLE_0:def 7;
A14: Down(B,C`) = B /\ C` by CONNSP_3:def 5;
      B c= C`
    proof
      let a be set; assume
A15:  a in B;
      then not a in C by A11,A13,XBOOLE_0:def 3;
      then a in (the carrier of TOP-REAL 2) \ C by A15,XBOOLE_0:def 4;
      hence a in C` by SUBSET_1:def 5;
    end;
    then Down(B,C`) = B by CONNSP_3:28;
    then Down(B,C`) is connected by A9,JORDAN2C:15;
then A16: Down(B,C`) c= skl Down(B,C`) by CONNSP_3:1;
      not x in C by A3,A5,A11,A13,XBOOLE_0:def 3;
    then x in (the carrier of TOP-REAL 2) \ C by A3,A5,XBOOLE_0:def 4;
    then x in C` by SUBSET_1:def 5;
then A17: x in B /\ C` by A3,A5,XBOOLE_0:def 3;
      P1 in {W where W is Subset of TOP-REAL 2: W is_outside_component_of C}
     by A12;
    hence x in UBD C by A1,A14,A16,A17,TARSKI:def 4;
  end;

definition
  let C be compact non vertical non horizontal Subset of TOP-REAL 2;
 func UBD-Family C equals :Def1:
  { UBD L~Cage(C,n) where n is Nat : not contradiction };
coherence;
 func BDD-Family C equals :Def2:
  { Cl BDD L~Cage(C,n) where n is Nat : not contradiction };
coherence;
end;

definition
  let C be compact non vertical non horizontal Subset of TOP-REAL 2;
 redefine func UBD-Family C -> Subset-Family of TOP-REAL 2;
coherence
  proof
      { UBD L~Cage(C,i) where i is Nat : not contradiction } c=
      bool the carrier of TOP-REAL 2
    proof
      let x be set; assume
        x in { UBD L~Cage(C,i) where i is Nat : not contradiction };
      then ex i being Nat st x = UBD L~Cage(C,i) & not contradiction;
      hence x in bool the carrier of TOP-REAL 2;
    end;
    then UBD-Family C c= bool the carrier of TOP-REAL 2 by Def1;
    then UBD-Family C is Subset-Family of TOP-REAL 2
      by SETFAM_1:def 7;
    hence thesis;
  end;
 redefine func BDD-Family C -> Subset-Family of TOP-REAL 2;
coherence
  proof
      { Cl BDD L~Cage(C,i) where i is Nat : not contradiction } c=
      bool the carrier of TOP-REAL 2
    proof
      let x be set; assume
        x in { Cl BDD L~Cage(C,i) where i is Nat : not contradiction };
      then ex i being Nat st x = Cl BDD L~Cage(C,i) & not contradiction;
      hence x in bool the carrier of TOP-REAL 2;
    end;
    then BDD-Family C c= bool the carrier of TOP-REAL 2 by Def2;
    then BDD-Family C is Subset-Family of TOP-REAL 2
      by SETFAM_1:def 7;
    hence thesis;
  end;
end;

definition
  let C be compact non vertical non horizontal Subset of TOP-REAL 2;
 cluster UBD-Family C -> non empty;
coherence
  proof
    consider m being Nat;
      { UBD L~Cage(C,i) where i is Nat : not contradiction } = UBD-Family C
      by Def1;
    then UBD L~Cage(C,m) in UBD-Family C;
    hence thesis;
  end;
 cluster BDD-Family C -> non empty;
coherence
  proof
    consider m being Nat;
      { Cl BDD L~Cage(C,i) where i is Nat : not contradiction } = BDD-Family C
      by Def2;
    then Cl BDD L~Cage(C,m) in BDD-Family C;
    hence thesis;
  end;
end;

theorem Th14:
 union UBD-Family C = UBD C
  proof
A1: UBD-Family C = { UBD L~Cage(C,n): not contradiction } by Def1;
      for X being set st X in UBD-Family C holds X c= UBD C
    proof
      let X be set;
      assume X in UBD-Family C;
      then ex n st X = UBD L~Cage(C,n) & not contradiction by A1;
      hence X c= UBD C by Th13;
    end;
    hence union UBD-Family C c= UBD C by ZFMISC_1:94;

    let x be set such that
A2:   x in UBD C;
      UBD C = union {B where B is Subset of TOP-REAL 2:
     B is_outside_component_of C} by JORDAN2C:def 6;
    then consider A being set such that
A3:   x in A and
A4:   A in {B where B is Subset of TOP-REAL 2:
        B is_outside_component_of C} by A2,TARSKI:def 4;
    consider B being Subset of TOP-REAL 2 such that
A5:   A = B and B is_outside_component_of C by A4;
    reconsider p = x as Point of TOP-REAL 2 by A3,A5;
    consider q being Point of TOP-REAL 2 such that
A6:   q`2 > N-bound L~Cage(C,0) and
A7:   p <> q by TOPREAL6:41;
A8: UBD L~Cage(C,0) c= UBD C by Th13;
A9: Cage(C,0)/.1 = N-min L~Cage(C,0) by JORDAN9:34;
A10: UBD L~Cage(C,0) = LeftComp Cage(C,0) by GOBRD14:46;
      q in LeftComp Cage(C,0) by A6,A9,JORDAN2C:121;
    then consider P such that
A11:   P is_S-P_arc_joining p,q and
A12:   P c= UBD C by A2,A7,A8,A10,TOPREAL4:30;
    consider f being FinSequence of TOP-REAL 2 such that
A13:   f is_S-Seq and
A14:   P = L~f and
A15:   p = f/.1 and q = f/.len f by A11,TOPREAL4:def 1;
    reconsider f as being_S-Seq FinSequence of TOP-REAL 2 by A13;
A16: L~f is non empty;
      TOP-REAL 2 = TopSpaceMetr Euclid 2 by EUCLID:def 8;
    then reconsider P1 = P, C1 = C as non empty compact Subset of
     TopSpaceMetr Euclid 2 by A14,A16;
    set d = min_dist_min(P1,C1);
      C is Bounded by JORDAN2C:73;
    then consider B being Subset of TOP-REAL 2 such that
A17:   B is_outside_component_of C & B = UBD C by JORDAN2C:76;
      UBD C is_a_component_of C` by A17,JORDAN2C:def 4;
    then C misses UBD C by GOBRD14:4;
    then P misses C by A12,XBOOLE_1:63;
    then d > 0 by JGRAPH_1:55;
    then d/2 > 0 by REAL_2:127;
    then consider n such that
         1 < n and
A18:   dist(Gauge(C,n)*(1,1),Gauge(C,n)*(1,2)) < d/2 and
A19:   dist(Gauge(C,n)*(1,1),Gauge(C,n)*(2,1)) < d/2 by GOBRD14:21;
    set G = Gauge(C,n),
        g = Cage(C,n);
      2 <= len f by SPPOL_1:2;
then A20: x in P by A14,A15,JORDAN3:34;
A21: now
      assume L~g /\ P <> {};
      then consider a being set such that
A22:     a in L~g /\ P by XBOOLE_0:def 1;
      reconsider a' = a as Point of Euclid 2 by A22,TOPREAL3:13;
      reconsider A = a as Point of TOP-REAL 2 by A22;
A23:   a in L~g & a in P by A22,XBOOLE_0:def 3;
      then consider i such that
A24:     1 <= i & i+1 <= len g and
A25:     a in LSeg(g,i) by SPPOL_2:13;
A26:   g is_sequence_on G by JORDAN9:def 1;
      then consider i1, j1, i2, j2 being Nat such that
A27:     [i1,j1] in Indices G and
A28:     g/.i = G*(i1,j1) and
A29:     [i2,j2] in Indices G and
A30:     g/.(i+1) = G*(i2,j2) and
A31:     i1 = i2 & j1+1 = j2 or i1+1 = i2 & j1 = j2 or
        i1 = i2+1 & j1 = j2 or i1 = i2 & j1 = j2+1 by A24,JORDAN8:6;
        right_cell(g,i,G) meets C by A24,JORDAN9:33;
      then consider c being set such that
A32:     c in right_cell(g,i,G) /\ C by XBOOLE_0:4;
      reconsider c as Point of Euclid 2 by A32,TOPREAL3:13;
      reconsider c' = c as Point of TOP-REAL 2 by A32;
        c in C by A32,XBOOLE_0:def 3;
then A33:   dist(a',c) >= d by A23,WEIERSTR:40;
      set e = E-bound C, w = W-bound C, p = N-bound C, s = S-bound C;
A34:   len G = width G by JORDAN8:def 1;
        4 <= len G by JORDAN8:13;
then A35:   1 <= len G & 1 <= width G & 1+1 <= len G & 1+1 <= width G
       by A34,AXIOMS:22;
      then [1,1] in Indices G & [1,1+1] in Indices G &
      [1+1,1] in Indices G by GOBOARD7:10;
then A36:   dist(G*(1,1),G*(1,1+1)) = (p-s)/2|^n &
      dist(G*(1,1),G*(1+1,1)) = (e-w)/2|^n by GOBRD14:19,20;
A37:   c in right_cell(g,i,G) by A32,XBOOLE_0:def 3;
        left_cell(g,i,G) /\ right_cell(g,i,G) = LSeg(g,i) by A24,A26,GOBRD13:30
;
      then A38:   a in right_cell(g,i,G) by A25,XBOOLE_0:def 3;
        now per cases by A31;
        case
A39:       i1 = i2 & j1+1 = j2;
then A40:     j1+1 <= width G by A29,GOBOARD5:1;
then A41:     1 <= i1 & i1 < len G & 1 <= j1 & j1 < width G
          by A24,A27,A28,A29,A30,A39,Th1,GOBOARD5:1,NAT_1:38;
A42:     right_cell(g,i,G) = cell(G,i1,j1)
              by A24,A26,A27,A28,A29,A30,A39,GOBRD13:23
          .= { |[r,t]| where r, t is Real :
                G*(i1,1)`1 <= r & r <= G*(i1+1,1)`1 &
                G*(1,j1)`2 <= t & t <= G*(1,j1+1)`2 } by A41,GOBRD11:32;
        then consider r, t being Real such that
A43:       c = |[r,t]| and
A44:       G*(i1,1)`1 <= r & r <= G*(i1+1,1)`1 &
          G*(1,j1)`2 <= t & t <= G*(1,j1+1)`2 by A37;
        consider aa, ab being Real such that
A45:       a = |[aa,ab]| and
A46:       G*(i1,1)`1 <= aa & aa <= G*(i1+1,1)`1 &
          G*(1,j1)`2 <= ab & ab <= G*(1,j1+1)`2 by A38,A42;
A47:     c'`1 = r & c'`2 = t & A`1 = aa & A`2 = ab by A43,A45,EUCLID:56;
      1 <= i1+1 & i1+1 <= len G & 1 <= j1+1 by A41,NAT_1:38;
then A48:     [i1,1] in Indices G & [i1+1,1] in Indices G &
         [1,j1] in Indices G & [1,j1+1] in Indices G
          by A35,A40,A41,GOBOARD7:10;
then A49:     dist(G*(i1,1),G*(i1+1,1)) = G*(i1+1,1)`1 - G*(i1,1)`1 &
         dist(G*(1,j1),G*(1,j1+1)) = G*(1,j1+1)`2 - G*(1,j1)`2
          by GOBRD14:15,16;
          dist(G*(1,j1),G*(1,j1+1)) = (p-s)/2|^n &
        dist(G*(i1,1),G*(i1+1,1)) = (e-w)/2|^n by A48,GOBRD14:19,20;
        hence dist(A,c') <= (p-s)/2|^n + (e-w)/2|^n by A44,A46,A47,A49,GOBRD14:
12;

        case
A50:       i1+1 = i2 & j1 = j2;
then A51:     i1+1 <= len G by A29,GOBOARD5:1;
          j2 > 1 by A24,A27,A28,A29,A30,A50,Th3;
then A52:     j2-1 > 0 by SQUARE_1:11;
then A53:     j2-1 = j2-'1 by BINARITH:def 3;
        A54: j2 <= width G by A29,GOBOARD5:1;
          width G - 1 < width G - 0 by REAL_1:92;
then A55:     1 <= i1 & i1 < len G & 1 <= j2-'1 & j2-'1 < width G
          by A27,A51,A52,A53,A54,GOBOARD5:1,NAT_1:38,REAL_1:92,RLVECT_1:99;
A56:     right_cell(g,i,G) = cell(G,i1,j2-'1)
              by A24,A26,A27,A28,A29,A30,A50,GOBRD13:25
          .= { |[r,t]| where r, t is Real :
                G*(i1,1)`1 <= r & r <= G*(i1+1,1)`1 &
                G*(1,j2-'1)`2 <= t & t <= G*(1,j2-'1+1)`2 } by A55,GOBRD11:32;
        then consider r, t being Real such that
A57:       c = |[r,t]| and
A58:       G*(i1,1)`1 <= r & r <= G*(i1+1,1)`1 &
          G*(1,j2-'1)`2 <= t & t <= G*(1,j2-'1+1)`2 by A37;
        consider aa, ab being Real such that
A59:       a = |[aa,ab]| and
A60:       G*(i1,1)`1 <= aa & aa <= G*(i1+1,1)`1 &
          G*(1,j2-'1)`2 <= ab & ab <= G*(1,j2-'1+1)`2 by A38,A56;
A61:     c'`1 = r & c'`2 = t & A`1 = aa & A`2 = ab by A57,A59,EUCLID:56;
A62:     1 <= i1+1 & i1+1 <= len G & j2-'1+1 <= width G by A55,NAT_1:38;
          1 <= j2-'1+1 by A55,NAT_1:38;
then A63:     [i1,1] in Indices G & [i1+1,1] in Indices G &
         [1,j2-'1] in Indices G & [1,j2-'1+1] in Indices G
          by A35,A55,A62,GOBOARD7:10;
then A64:     dist(G*(i1,1),G*(i1+1,1)) = G*(i1+1,1)`1 - G*(i1,1)`1 &
         dist(G*(1,j2-'1),G*(1,j2-'1+1)) = G*(1,j2-'1+1)`2 - G*(1,j2-'1)`2
          by GOBRD14:15,16;
          dist(G*(1,j2-'1),G*(1,j2-'1+1)) = (p-s)/2|^n &
        dist(G*(i1,1),G*(i1+1,1)) = (e-w)/2|^n by A63,GOBRD14:19,20;
        hence dist(A,c') <= (p-s)/2|^n + (e-w)/2|^n by A58,A60,A61,A64,GOBRD14:
12;

        case
A65:       i1 = i2+1 & j1 = j2;
        then i2+1 <= len G by A27,GOBOARD5:1;
then A66:     1 <= i2 & i2 < len G & 1 <= j1 & j1 < width G
          by A24,A27,A28,A29,A30,A65,Th4,GOBOARD5:1,NAT_1:38;
A67:     right_cell(g,i,G) = cell(G,i2,j1)
              by A24,A26,A27,A28,A29,A30,A65,GOBRD13:27
          .= { |[r,t]| where r, t is Real :
                G*(i2,1)`1 <= r & r <= G*(i2+1,1)`1 &
                G*(1,j1)`2 <= t & t <= G*(1,j1+1)`2 } by A66,GOBRD11:32;
        then consider r, t being Real such that
A68:       c = |[r,t]| and
A69:       G*(i2,1)`1 <= r & r <= G*(i2+1,1)`1 &
          G*(1,j1)`2 <= t & t <= G*(1,j1+1)`2 by A37;
        consider aa, ab being Real such that
A70:       a = |[aa,ab]| and
A71:       G*(i2,1)`1 <= aa & aa <= G*(i2+1,1)`1 &
          G*(1,j1)`2 <= ab & ab <= G*(1,j1+1)`2 by A38,A67;
A72:     c'`1 = r & c'`2 = t & A`1 = aa & A`2 = ab by A68,A70,EUCLID:56;
A73:     1 <= i2+1 & i2+1 <= len G & j1+1 <= width G by A66,NAT_1:38;
          1 <= j1+1 by NAT_1:37;
then A74:     [i2,1] in Indices G & [i2+1,1] in Indices G &
         [1,j1] in Indices G & [1,j1+1] in Indices G
          by A35,A66,A73,GOBOARD7:10;
then A75:     dist(G*(i2,1),G*(i2+1,1)) = G*(i2+1,1)`1 - G*(i2,1)`1 &
         dist(G*(1,j1),G*(1,j1+1)) = G*(1,j1+1)`2 - G*(1,j1)`2
          by GOBRD14:15,16;
          dist(G*(1,j1),G*(1,j1+1)) = (p-s)/2|^n &
        dist(G*(i2,1),G*(i2+1,1)) = (e-w)/2|^n by A74,GOBRD14:19,20;
        hence dist(A,c') <= (p-s)/2|^n + (e-w)/2|^n by A69,A71,A72,A75,GOBRD14:
12;

        case
A76:       i1 = i2 & j1 = j2+1;
then A77:     j2+1 <= width G by A27,GOBOARD5:1;
          i1 > 1 by A24,A27,A28,A29,A30,A76,Th2;
then A78:     i1-1 > 0 by SQUARE_1:11;
then A79:     i1-1 = i1-'1 by BINARITH:def 3;
        A80: i1 <= len G by A27,GOBOARD5:1;
          len G - 1 < len G - 0 by REAL_1:92;
then A81:     1 <= i1-'1 & i1-'1 < len G & 1 <= j2 & j2 < width G
          by A29,A77,A78,A79,A80,GOBOARD5:1,NAT_1:38,REAL_1:92,RLVECT_1:99;
A82:     right_cell(g,i,G) = cell(G,i1-'1,j2)
              by A24,A26,A27,A28,A29,A30,A76,GOBRD13:29
          .= { |[r,t]| where r, t is Real :
                G*(i1-'1,1)`1 <= r & r <= G*(i1-'1+1,1)`1 &
                G*(1,j2)`2 <= t & t <= G*(1,j2+1)`2 } by A81,GOBRD11:32;
        then consider r, t being Real such that
A83:       c = |[r,t]| and
A84:       G*(i1-'1,1)`1 <= r & r <= G*(i1-'1+1,1)`1 &
          G*(1,j2)`2 <= t & t <= G*(1,j2+1)`2 by A37;
        consider aa, ab being Real such that
A85:       a = |[aa,ab]| and
A86:       G*(i1-'1,1)`1 <= aa & aa <= G*(i1-'1+1,1)`1 &
          G*(1,j2)`2 <= ab & ab <= G*(1,j2+1)`2 by A38,A82;
A87:     c'`1 = r & c'`2 = t & A`1 = aa & A`2 = ab by A83,A85,EUCLID:56;
      1 <= i1-'1+1 & i1-'1+1 <= len G & 1 <= j2+1 by A81,NAT_1:38;
then A88:     [i1-'1,1] in Indices G & [i1-'1+1,1] in Indices G &
         [1,j2] in Indices G & [1,j2+1] in Indices G
          by A35,A77,A81,GOBOARD7:10;
then A89:     dist(G*(i1-'1,1),G*(i1-'1+1,1)) = G*(i1-'1+1,1)`1 - G*(i1-'1,1)`1
&
         dist(G*(1,j2),G*(1,j2+1)) = G*(1,j2+1)`2 - G*(1,j2)`2
          by GOBRD14:15,16;
          dist(G*(1,j2),G*(1,j2+1)) = (p-s)/2|^n &
        dist(G*(i1-'1,1),G*
(i1-'1+1,1)) = (e-w)/2|^n by A88,GOBRD14:19,20;
        hence dist(A,c') <= (p-s)/2|^n + (e-w)/2|^n by A84,A86,A87,A89,GOBRD14:
12;
      end;
then A90:   dist(a',c) <= (p-s)/2|^n + (e-w)/2|^n by GOBRD14:def 1;
        (p-s)/2|^n + (e-w)/2|^n < d/2 + d/2 by A18,A19,A36,REAL_1:67;
      then (p-s)/2|^n + (e-w)/2|^n < d by XCMPLX_1:66;
      hence contradiction by A33,A90,AXIOMS:22;
    end;
      L~g is Bounded by JORDAN2C:73;
    then consider B being Subset of TOP-REAL 2 such that
A91:   B is_outside_component_of L~g and
A92:   B = UBD L~g by JORDAN2C:76;
    consider E being Subset of (TOP-REAL 2)|(L~g)` such that
A93:   E = B & E is_a_component_of (TOP-REAL 2)|(L~g)` and
        not E is bounded Subset of Euclid 2 by A91,JORDAN2C:18;
A94: P c= (L~g)`
    proof
      let a be set;
      assume
A95:     a in P;
      then not a in L~g by A21,XBOOLE_0:def 3;
      hence thesis by A95,SUBSET_1:50;
    end;
A96: P is_an_arc_of p,q by A11,A14,A16,TOPREAL4:3;
then A97: P is connected by JORDAN6:11;
A98: UBD L~g is_a_component_of (L~g)` by A92,A93,CONNSP_1:def 6;
A99: g/.1 = N-min L~g by JORDAN9:34;
     0 < n or 0 = n by NAT_1:18;
    then N-bound L~(Cage(C,0)) >= N-bound L~g by Th7;
    then q`2 > N-bound L~g by A6,AXIOMS:22;
    then q in LeftComp g by A99,JORDAN2C:121;
    then q in UBD L~g by GOBRD14:46;
then A100: {q} c= UBD L~g by ZFMISC_1:37;
      {q} meets P
    proof
        now take a = q;
      thus a in {q} & a in P by A96,TARSKI:def 1,TOPREAL1:4;
     end; hence thesis by XBOOLE_0:3;
    end;
then A101: P c= UBD L~g by A94,A97,A98,A100,GOBOARD9:6;
      UBD L~g in UBD-Family C by A1;
    hence x in union UBD-Family C by A20,A101,TARSKI:def 4;
 end;

theorem Th15:
 C c= meet BDD-Family C
  proof
A1: BDD-Family C = { Cl BDD L~Cage(C,k) where k is Nat : not contradiction }
      by Def2;
      for Z being set st Z in BDD-Family C holds C c= Z
    proof
      let Z be set;
      assume Z in BDD-Family C;
       then consider k being Nat such that
A2:     Z = Cl BDD L~Cage(C,k) by A1;
A3:     C c= BDD L~Cage(C,k) by Th12;
        BDD L~Cage(C,k) c= Cl BDD L~Cage(C,k) by PRE_TOPC:48;
     hence thesis by A2,A3,XBOOLE_1:1;
    end;
    hence thesis by SETFAM_1:6;
  end;

theorem Th16:
 BDD C misses LeftComp Cage(C,n)
  proof
    set f = Cage(C,n);
    assume BDD C /\ LeftComp f <> {};
    then consider x being Point of TOP-REAL 2 such that
A1:   x in BDD C /\ LeftComp f by SUBSET_1:10;
A2: x in BDD C & x in LeftComp f by A1,XBOOLE_0:def 3;
A3: UBD-Family C = { UBD L~Cage(C,k) where k is Nat : not contradiction }
      by Def1;
      BDD C misses UBD C by JORDAN2C:28;
    then BDD C /\ UBD C = {} by XBOOLE_0:def 7;
    then not x in UBD C by A2,XBOOLE_0:def 3;
then A4: not x in union UBD-Family C by Th14;
      UBD L~f in { UBD L~Cage(C,k) where k is Nat : not contradiction };
 then not x in UBD L~f by A3,A4,TARSKI:def 4;
    hence contradiction by A2,GOBRD14:46;
  end;

theorem Th17:
 BDD C c= RightComp Cage(C,n)
  proof
    set f = Cage(C,n);
    let x be set;
    assume
A1:   x in BDD C;
A2: UBD-Family C = { UBD L~Cage(C,k) where k is Nat : not contradiction }
      by Def1;
      BDD C misses UBD C by JORDAN2C:28;
    then BDD C /\ UBD C = {} by XBOOLE_0:def 7;
    then not x in UBD C by A1,XBOOLE_0:def 3;
then A3: not x in union UBD-Family C by Th14;
      UBD L~f in { UBD L~Cage(C,k) where k is Nat : not contradiction };
then A4: not x in UBD L~Cage(C,n) by A2,A3,TARSKI:def 4;
A5: UBD L~f = union {E where E is Subset of TOP-REAL 2:
        E is_outside_component_of L~f} by JORDAN2C:def 6;
      LeftComp f is_outside_component_of L~f by GOBRD14:44;
    then LeftComp f in {E where E is Subset of TOP-REAL 2:
        E is_outside_component_of L~f};
then A6: not x in LeftComp f by A4,A5,TARSKI:def 4;
A7: L~f = (Cl LeftComp f) \ LeftComp f by GOBRD14:30;
      now
      assume x in Cl LeftComp f;
      then BDD C meets LeftComp f by A1,PRE_TOPC:def 13;
      hence contradiction by Th16;
    end;
    then not x in L~f by A7,XBOOLE_0:def 4;
    hence x in RightComp f by A1,A6,GOBRD14:28;
  end;

theorem Th18:
 P is_inside_component_of C implies P misses L~Cage(C,n)
  proof
    set f = Cage(C,n);
    assume
A1:   P is_inside_component_of C;
    assume P /\ L~f <> {};
    then consider x being Point of TOP-REAL 2 such that
A2:   x in P /\ L~f by SUBSET_1:10;
A3: x in P & x in L~f by A2,XBOOLE_0:def 3;
      P c= BDD C by A1,JORDAN2C:26;
then A4: x in BDD C by A3;
      BDD C c= RightComp f by Th17;
    hence contradiction by A3,A4,GOBRD14:28;
  end;

theorem Th19:
 BDD C misses L~Cage(C,n)
  proof
A1: BDD C = union {B where B is Subset of TOP-REAL 2:
      B is_inside_component_of C} by JORDAN2C:def 5;
    assume not thesis;
    then consider x being set such that
A2:   x in BDD C /\ L~Cage(C,n) by XBOOLE_0:4;
      x in BDD C by A2,XBOOLE_0:def 3;
    then consider Z being set such that
A3:   x in Z & Z in {B where B is Subset of TOP-REAL 2:
      B is_inside_component_of C} by A1,TARSKI:def 4;
    consider B being Subset of TOP-REAL 2 such that
A4:   Z = B & B is_inside_component_of C by A3;
      B misses L~Cage(C,n) by A4,Th18;
then A5: B /\ L~Cage(C,n) = {} by XBOOLE_0:def 7;
      x in L~Cage(C,n) by A2,XBOOLE_0:def 3;
    hence thesis by A3,A4,A5,XBOOLE_0:def 3;
  end;

theorem Th20:
 COMPLEMENT UBD-Family C = BDD-Family C
 proof
A1: BDD-Family C = { Cl BDD L~Cage(C,k) where k is Nat : not contradiction }
      by Def2;
A2: UBD-Family C = { UBD L~Cage(C,n): not contradiction } by Def1;
     for P being Subset of TOP-REAL 2
     holds P in BDD-Family C iff P` in UBD-Family C
   proof let P being Subset of TOP-REAL 2;
     thus P in BDD-Family C implies P` in UBD-Family C
      proof assume P in BDD-Family C;
        then consider k such that
A3:      P = Cl BDD L~Cage(C,k) by A1;
          P = Cl RightComp Cage(C,k) by A3,GOBRD14:47;
        then A4:        P = (RightComp Cage(C,k)) \/ L~Cage(C,k) by GOBRD14:31;
A5:      L~Cage(C,k) misses LeftComp Cage(C,k) by SPRECT_3:43;
          RightComp Cage(C,k) misses LeftComp Cage(C,k) by GOBRD14:24;
        then A6:      P misses LeftComp Cage(C,k) by A4,A5,XBOOLE_1:70;
A7:      P \/ LeftComp Cage(C,k) = the carrier of TOP-REAL 2 by A4,GOBRD14:25;
          P` /\ (LeftComp Cage(C,k))` = (P \/ LeftComp Cage(C,k))` by SUBSET_1:
29
                .= ([#]the carrier of TOP-REAL 2)` by A7,SUBSET_1:def 4
                .= {}the carrier of TOP-REAL 2 by SUBSET_1:21;
        then P` misses (LeftComp Cage(C,k))` by XBOOLE_0:def 7;
        then P` = LeftComp Cage(C,k) by A6,SUBSET_1:46;
        then P` = UBD L~Cage(C,k) by GOBRD14:46;
       hence P` in UBD-Family C by A2;
      end;
    assume P` in UBD-Family C;
     then consider k such that
A8:    P` = UBD L~Cage(C,k) by A2;
A9:   P` = LeftComp Cage(C,k) by A8,GOBRD14:46;
then A10:   P` misses RightComp Cage(C,k) by GOBRD14:24;
       P` misses L~Cage(C,k) by A9,SPRECT_3:43;
     then P` misses (RightComp Cage(C,k)) \/ L~Cage(C,k) by A10,XBOOLE_1:70;
     then A11:   P` misses Cl RightComp Cage(C,k) by GOBRD14:31;
A12:   P` \/ ((RightComp Cage(C,k)) \/ L~Cage(C,k))
            = the carrier of TOP-REAL 2 by A9,GOBRD14:25;
       P`` /\ (Cl RightComp Cage(C,k))`
              = (P` \/ (Cl RightComp Cage(C,k)))` by SUBSET_1:29
             .= (P` \/ ((RightComp Cage(C,k)) \/ L~Cage(C,k)))` by GOBRD14:31
             .= ([#]the carrier of TOP-REAL 2)` by A12,SUBSET_1:def 4
             .= {}the carrier of TOP-REAL 2 by SUBSET_1:21;
     then P`` misses (Cl RightComp Cage(C,k))` by XBOOLE_0:def 7;
     then P`` = Cl RightComp Cage(C,k) by A11,SUBSET_1:46;
     then P = Cl BDD L~Cage(C,k) by GOBRD14:47;
    hence P in BDD-Family C by A1;
   end;
  hence thesis by SETFAM_1:def 8;
 end;

theorem
   meet BDD-Family C = C \/ BDD C
  proof
      (BDD C) misses (UBD C) by JORDAN2C:28;
then A1: (BDD C) /\ (UBD C) = {} by XBOOLE_0:def 7;
A2: UBD-Family C = { UBD L~Cage(C,n) where n is Nat : not contradiction }
      by Def1;
A3: BDD-Family C = { Cl BDD L~Cage(C,n) where n is Nat : not contradiction }
      by Def2;
    thus meet BDD-Family C c= C \/ BDD C
    proof
      let x be set;
      assume
A4:     x in meet BDD-Family C;
         COMPLEMENT UBD-Family C = BDD-Family C by Th20;
       then ([#] the carrier of TOP-REAL 2) \ union UBD-Family C
         = meet BDD-Family C by SETFAM_1:47;
      then not x in union UBD-Family C by A4,XBOOLE_0:def 4;
      then A5:   not x in UBD C by Th14;
      per cases;
      suppose not x in C;
then A6:   x in C` by A4,SUBSET_1:50;
        BDD C \/ UBD C = C` by JORDAN2C:31;
      then x in BDD C by A5,A6,XBOOLE_0:def 2;
      hence x in C \/ BDD C by XBOOLE_0:def 2;
      suppose x in C;
      hence x in C \/ BDD C by XBOOLE_0:def 2;
    end;
A7: BDD C c= meet BDD-Family C
    proof
      let x be set;
      assume
A8:     x in BDD C;
      then not x in UBD C by A1,XBOOLE_0:def 3;
then A9:   not x in union UBD-Family C by Th14;
        for Y being set st Y in BDD-Family C holds x in Y
      proof
        let Y be set;
        assume Y in BDD-Family C;
        then consider n such that
A10:       Y = Cl BDD L~Cage(C,n) and not contradiction by A3;
A11:     UBD L~Cage(C,n) = union{B where B is Subset of TOP-REAL 2:
          B is_outside_component_of L~Cage(C,n)} by JORDAN2C:def 6;
A12:     BDD L~Cage(C,n) = union{B where B is Subset of TOP-REAL 2:
          B is_inside_component_of L~Cage(C,n)} by JORDAN2C:def 5;
          UBD L~Cage(C,n) in UBD-Family C by A2;
then A13:     not x in UBD L~Cage(C,n) by A9,TARSKI:def 4;
          LeftComp Cage(C,n) is_outside_component_of L~Cage(C,n) by GOBRD14:44;
        then LeftComp Cage(C,n) in {B where B is Subset of TOP-REAL 2:
          B is_outside_component_of L~Cage(C,n)};
then A14:     not x in LeftComp Cage(C,n) by A11,A13,TARSKI:def 4;
          BDD C misses L~Cage(C,n) by Th19;
        then BDD C /\ L~Cage(C,n) = {} by XBOOLE_0:def 7;
        then not x in L~Cage(C,n) by A8,XBOOLE_0:def 3;
then A15:     x in RightComp Cage(C,n) by A8,A14,GOBRD14:28;
          RightComp Cage(C,n) is_inside_component_of L~Cage(C,n)
          by GOBRD14:45;
        then RightComp Cage(C,n) in {B where B is Subset of TOP-REAL 2:
          B is_inside_component_of L~Cage(C,n)};
then A16:       x in BDD L~Cage(C,n) by A12,A15,TARSKI:def 4;
           BDD L~Cage(C,n) c= Cl BDD L~Cage(C,n) by PRE_TOPC:48;
        hence x in Y by A10,A16;
      end;
      hence x in meet BDD-Family C by SETFAM_1:def 1;
    end;
      C c= meet BDD-Family C by Th15;
    hence thesis by A7,XBOOLE_1:8;
  end;

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