The Mizar article:

Preparing the Internal Approximations of Simple Closed Curves

by
Andrzej Trybulec

Received May 21, 2002

Copyright (c) 2002 Association of Mizar Users

MML identifier: JORDAN11
[ MML identifier index ]


environ

 vocabulary JORDAN1A, JORDAN11, JORDAN8, EUCLID, GROUP_1, FINSEQ_1, ARYTM_1,
      SEQ_1, BOOLE, GOBOARD5, SETFAM_1, SQUARE_1, FUNCT_1, PSCOMP_1, RCOMP_1,
      RELAT_2, JORDAN2C, JORDAN6, JORDAN9, PRE_TOPC, RELAT_1, TARSKI, ORDINAL2,
      CONNSP_1, COMPTS_1, MCART_1, TOPREAL1, TOPREAL2, GOBOARD9, ARYTM_3,
      SUBSET_1, LATTICES, NAT_1, INT_1, JORDAN10, SEQ_2, FUNCT_5, TREES_1,
      MATRIX_1, JORDAN1H, JORDAN1E, ARYTM;
 notation TARSKI, XBOOLE_0, ZFMISC_1, SUBSET_1, ORDINAL1, NUMBERS, XREAL_0,
      REAL_1, INT_1, NAT_1, BINARITH, CARD_4, CQC_SIM1, RELAT_1, FUNCT_2,
      FINSEQ_1, MATRIX_1, SEQ_1, SEQ_4, RCOMP_1, STRUCT_0, PRE_TOPC, CONNSP_1,
      COMPTS_1, EUCLID, TOPREAL1, TOPREAL2, GOBOARD5, GOBOARD9, PSCOMP_1,
      JORDAN2C, JORDAN6, JCT_MISC, JORDAN8, JORDAN9, JORDAN10, JORDAN1A,
      JORDAN1E, JORDAN1H;
 constructors TOPREAL2, JORDAN8, JORDAN2C, BINARITH, REALSET1, GOBOARD9,
      JORDAN1, RCOMP_1, PSCOMP_1, CONNSP_1, CQC_SIM1, REAL_1, CARD_4, TOPS_1,
      JORDAN6, JORDAN9, JORDAN5C, JORDAN1A, JORDAN10, WSIERP_1, JCT_MISC,
      JORDAN1H, JORDAN1E, PARTFUN1, INT_1;
 clusters SPRECT_3, BORSUK_2, TOPREAL6, XREAL_0, SUBSET_1, PSCOMP_1, REVROT_1,
      JORDAN8, INT_1, JORDAN1A, JORDAN1B, JORDAN10, MEMBERED, NUMBERS,
      ORDINAL2;
 requirements NUMERALS, REAL, SUBSET, BOOLE, ARITHM;
 definitions TARSKI, XBOOLE_0, JORDAN1H;
 theorems AXIOMS, CQC_SIM1, JORDAN8, REAL_1, AMI_5, NEWTON, JORDAN3, NAT_1,
      GOBOARD7, RLVECT_1, GOBOARD5, INT_1, SPRECT_3, XBOOLE_0, XBOOLE_1,
      JORDAN2C, SUBSET_1, GOBOARD9, ZFMISC_1, CQC_THE1, EUCLID, GOBOARD1,
      BINARITH, JORDAN6, PSCOMP_1, SPRECT_1, TARSKI, TOPREAL3, SETFAM_1,
      RCOMP_1, RELAT_1, FUNCT_2, TOPREAL1, PRE_TOPC, COMPTS_1, JORDAN1A,
      ENUMSET1, SEQ_4, FUNCT_1, XREAL_0, SCMFSA9A, JCT_MISC, JORDAN10, GOBRD14,
      JORDAN1B, JORDAN1C, SCMFSA_7, PCOMPS_2, JORDAN1F, JORDAN1G, JORDAN1H,
      JORDAN1I, JORDAN1J, PREPOWER, XCMPLX_1;
 schemes DOMAIN_1, FUNCT_2;

begin

reserve i,j,k,n for Nat,
        C for being_simple_closed_curve Subset of TOP-REAL 2;

Lm1:
 i > 0 &
 1 <= j & j <= width Gauge(C,i) & k <= j &
 1 <= k & k <= width Gauge(C,i) &
 LSeg(Gauge(C,i)*(Center Gauge(C,i),j),Gauge(C,i)*(Center Gauge(C,i),k))
    /\ Upper_Arc L~Cage(C,i) = {Gauge(C,i)*(Center Gauge(C,i),j)} &
 LSeg(Gauge(C,i)*(Center Gauge(C,i),j),Gauge(C,i)*(Center Gauge(C,i),k))
    /\ Lower_Arc L~Cage(C,i) = {Gauge(C,i)*(Center Gauge(C,i),k)}
 implies
 LSeg(Gauge(C,i)*(Center Gauge(C,i),j),Gauge(C,i)*(Center Gauge(C,i),k))
       c= Cl RightComp Cage(C,i)
proof assume that
A1: i > 0 and
A2: 1 <= j and
A3: j <= width Gauge(C,i) and
A4: k <= j and
A5: 1 <= k and
A6: k <= width Gauge(C,i) and
A7: LSeg(Gauge(C,i)*(Center Gauge(C,i),j),Gauge(C,i)*(Center Gauge(C,i),k))
    /\ Upper_Arc L~Cage(C,i) = {Gauge(C,i)*(Center Gauge(C,i),j)} and
A8: LSeg(Gauge(C,i)*(Center Gauge(C,i),j),Gauge(C,i)*(Center Gauge(C,i),k))
    /\ Lower_Arc L~Cage(C,i) = {Gauge(C,i)*(Center Gauge(C,i),k)};
  set p = Gauge(C,i)*(Center Gauge(C,i),j),
      q = Gauge(C,i)*(Center Gauge(C,i),k),
      S = RightComp Cage(C,i);
     X-SpanStart(C,i) = Center Gauge(C,i) by JORDAN1H:57;
   then 2 <= Center Gauge(C,i) & Center Gauge(C,i) < len Gauge(C,i)
       by JORDAN1H:58;
   then A9: 1 < Center Gauge(C,i) & Center Gauge(C,i) < len Gauge(C,i)
       by AXIOMS:22;
      q in {q} by TARSKI:def 1;
    then q in Lower_Arc L~Cage(C,i) by A8,XBOOLE_0:def 3;
    then A10: q in L~Lower_Seq(C,i) by A1,JORDAN1G:64;
      p in {p} by TARSKI:def 1;
    then p in Upper_Arc L~Cage(C,i) by A7,XBOOLE_0:def 3;
    then p in L~Upper_Seq(C,i) by A1,JORDAN1G:63;
    then A11:  j <> k by A2,A6,A9,A10,JORDAN1J:57;
A12: [Center Gauge(C,i),j] in Indices Gauge(C,i) by A2,A3,A9,GOBOARD7:10;
     [Center Gauge(C,i),k] in Indices Gauge(C,i) by A5,A6,A9,GOBOARD7:10;
   then A13: p <> q by A11,A12,JORDAN1H:32;
   set A = LSeg(p,q) \ {p,q};
A14: A is connected by JORDAN1H:5;
A15: S is_a_component_of (L~Cage(C,i))` by GOBOARD9:def 2;
     LSeg(p,q) /\ L~Cage(C,i)
       = LSeg(p,q) /\ (Upper_Arc L~Cage(C,i) \/ Lower_Arc L~Cage(C,i))
           by JORDAN6:65
      .= LSeg(p,q) /\ Upper_Arc L~Cage(C,i) \/
         LSeg(p,q) /\ Lower_Arc L~Cage(C,i) by XBOOLE_1:23
      .= {p,q} by A7,A8,ENUMSET1:41;
   then A misses L~Cage(C,i) by XBOOLE_1:90;
   then A16: A c= (L~Cage(C,i))` by SUBSET_1:43;
A17: LSeg(q,p) meets Upper_Arc C by A1,A3,A4,A5,A7,A8,A9,JORDAN1J:61;
      Upper_Arc C c= C by JORDAN1A:16;
    then A18: LSeg(q,p) meets C by A17,XBOOLE_1:63;
A19: {p} c= Upper_Arc L~Cage(C,i) by A7,XBOOLE_1:17;
      {q} c= Lower_Arc L~Cage(C,i) by A8,XBOOLE_1:17;
    then {p} \/ {q} c= Upper_Arc L~Cage(C,i) \/ Lower_Arc L~Cage(C,i)
       by A19,XBOOLE_1:13;
    then {p} \/ {q} c= L~Cage(C,i) by JORDAN6:65;
    then A20: {p,q} c= L~Cage(C,i) by ENUMSET1:41;
      L~Cage(C,i) misses C by JORDAN10:5;
    then {p,q} misses C by A20,XBOOLE_1:63;
    then A21: A meets C by A18,XBOOLE_1:84;
    C c= S by JORDAN10:11;
  then A meets S by A21,XBOOLE_1:63;
  then A c= S by A14,A15,A16,JORDAN1A:8;
 hence LSeg(p,q) c= Cl S by A13,JORDAN1H:8;
end;

Lm2:
 ex n st n is_sufficiently_large_for C
proof
  set s = (W-bound C + E-bound C)/2,
      e = Gauge(C,1)*(X-SpanStart(C,1),len Gauge(C,1)),
      f = Gauge(C,1)*(X-SpanStart(C,1),1);
A1: X-SpanStart(C,1) = Center Gauge(C,1) by JORDAN1H:57;
  then X-SpanStart(C,1) = (len Gauge(C,1)) div 2 + 1 by JORDAN1A:def 1;
  then A2: 1 <= X-SpanStart(C,1) by NAT_1:29;
  A3: len Gauge(C,1) >= 4 by JORDAN8:13;
then A4: 1 < len Gauge(C,1) by AXIOMS:22;
then A5: f`1 = s by A1,JORDAN1A:59;
then A6: f in Vertical_Line s by JORDAN1A:17;
A7: e`1 = s by A1,A4,JORDAN1A:59;
  then e in Vertical_Line s by JORDAN1A:17;
  then A8: LSeg(e,f) c= Vertical_Line s by A6,JORDAN1A:23;
A9: len Gauge(C,1) = width Gauge(C,1) by JORDAN8:def 1;
    0 < len Gauge(C,1) by A3,AXIOMS:22;
  then len Gauge(C,1) qua Integer div 2 < len Gauge(C,1) by SCMFSA9A:4;
  then (len Gauge(C,1)) div 2 < len Gauge(C,1) by SCMFSA9A:5;
  then (len Gauge(C,1)) div 2 + 1 <= len Gauge(C,1) by NAT_1:38;
  then X-SpanStart(C,1) <= len Gauge(C,1) by A1,JORDAN1A:def 1;
  then A10: f`2 < e`2 by A2,A4,A9,GOBOARD5:5;
A11: proj2.f = f`2 & proj2.e = e`2 by PSCOMP_1:def 29;
A12: W-bound C < E-bound C by SPRECT_1:33;
deffunc F(Nat)=inf(proj2.:(LSeg(f,e) /\ Upper_Arc L~Cage(C,$1+1)));
  consider Es being Real_Sequence such that
A13: for i being Nat holds Es.i =
       F(i) from LambdaD;
deffunc G(Nat)=|[s,Es.$1]|;
       consider E being Function of NAT, the carrier of TOP-REAL 2 such that
A14: for i being Nat holds E.i = G(i) from LambdaD;
deffunc H(Nat)=sup(proj2.:(LSeg(f,E.$1) /\ Lower_Arc L~Cage(C,$1+1)));
consider Fs being Real_Sequence such that
A15: for i being Nat holds Fs.i =
       H(i) from LambdaD;
deffunc I(Nat)=|[s,Fs.$1]|;
       consider F being Function of NAT, the carrier of TOP-REAL 2 such that
A16: for i being Nat holds F.i = I(i) from LambdaD;
  set e1 = proj2.e, f1 = proj2.f;
A17: for i holds E.i in Upper_Arc L~Cage(C,i+1)
   proof let i;
     set p = E.i;
A18:  X-SpanStart(C,i+1) = Center Gauge(C,i+1) by JORDAN1H:57;
     then A19:  LSeg(Gauge(C,i+1)*(X-SpanStart(C,i+1),1),
           Gauge(C,i+1)*(X-SpanStart(C,i+1),len Gauge(C,i+1)))
          meets Upper_Arc L~Cage(C,i+1) by JORDAN1B:34;
       i+1 >= 1 by NAT_1:29;
     then LSeg(Gauge(C,i+1)*(X-SpanStart(C,i+1),1),
           Gauge(C,i+1)*(X-SpanStart(C,i+1),len Gauge(C,i+1)))
                 c= LSeg(f,e) by A1,A18,JORDAN1A:65;
     then A20:  LSeg(f,e) meets Upper_Arc L~Cage(C,i+1) by A19,XBOOLE_1:63;
       E.i = |[s,Es.i]| by A14;
     then A21:    p`1 = s & p`2 = Es.i by EUCLID:56;
     reconsider DD = LSeg(f,e) /\ Upper_Arc L~Cage(C,i+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
     reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
        DD c= the carrier of TOP-REAL 2;
     then DD c= dom proj2 by FUNCT_2:def 1;
     then A22:    dom proj2 /\ DD = DD by XBOOLE_1:28;
       DD <> {} by A20,XBOOLE_0:def 7;
     then dom proj2 meets DD by A22,XBOOLE_0:def 7;
     then A23:    D <> {} by RELAT_1:151;
       Es.i = inf D by A13;
     then Es.i in D by A23,RCOMP_1:32;
     then consider dd being Point of TOP-REAL 2 such that
A24:   dd in DD and
A25:   Es.i = proj2.dd by FUNCT_2:116;
A26:  dd in Upper_Arc L~Cage(C,i+1) by A24,XBOOLE_0:def 3;
       dd in LSeg(e,f) by A24,XBOOLE_0:def 3;
     then A27:   dd`1 = p`1 by A8,A21,JORDAN6:34;
       dd`2 = p`2 by A21,A25,PSCOMP_1:def 29;
    hence E.i in Upper_Arc L~Cage(C,i+1) by A26,A27,TOPREAL3:11;
   end;
A28: for i holds F.i in Lower_Arc L~Cage(C,i+1)
   proof let i;
     set p = F.i;
A29:  X-SpanStart(C,i+1) = Center Gauge(C,i+1) by JORDAN1H:57;
A30: E.i = |[s,Es.i]| by A14;
     then A31: (E.i)`1 = s by EUCLID:56;
       (E.i)`2 = Es.i by A30,EUCLID:56
          .= inf(proj2.:(LSeg(f,e) /\ Upper_Arc L~Cage(C,i+1))) by A13;
     then consider j such that
A32:    1 <= j and
A33:    j <= width Gauge(C,i+1) and
A34:    E.i = Gauge(C,i+1)*(X-SpanStart(C,i+1),j)
      by A1,A9,A29,A31,JORDAN1F:13;
       E.i in Upper_Arc L~Cage(C,i+1) by A17;
     then A35:   LSeg(f,E.i)
          meets Lower_Arc L~Cage(C,i+1) by A1,A29,A32,A33,A34,JORDAN1J:62;
       F.i = |[s,Fs.i]| by A16;
     then A36:    p`1 = s & p`2 = Fs.i by EUCLID:56;
     reconsider DD = LSeg(f,E.i) /\ Lower_Arc L~Cage(C,i+1)
           as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
     reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
       DD c= the carrier of TOP-REAL 2;
     then DD c= dom proj2 by FUNCT_2:def 1;
     then A37:    dom proj2 /\ DD = DD by XBOOLE_1:28;
       DD <> {} by A35,XBOOLE_0:def 7;
     then dom proj2 meets DD by A37,XBOOLE_0:def 7;
     then A38:    D <> {} by RELAT_1:151;
       Fs.i = sup D by A15;
     then Fs.i in D by A38,RCOMP_1:32;
     then consider dd being Point of TOP-REAL 2 such that
A39:   dd in DD and
A40:   Fs.i = proj2.dd by FUNCT_2:116;
A41:  dd in Lower_Arc L~Cage(C,i+1) by A39,XBOOLE_0:def 3;
A42:  dd in LSeg(E.i,f) by A39,XBOOLE_0:def 3;
       E.i in Vertical_Line s by A31,JORDAN1A:17;
     then LSeg(E.i,f) c= Vertical_Line s by A6,JORDAN1A:23;
     then A43:   dd`1 = p`1 by A36,A42,JORDAN6:34;
       dd`2 = p`2 by A36,A40,PSCOMP_1:def 29;
    hence F.i in Lower_Arc L~Cage(C,i+1) by A41,A43,TOPREAL3:11;
   end;
A44: proj2.:LSeg(f,e) = [.f1,e1.] by A10,A11,SPRECT_1:61;
deffunc F(Nat)=proj2.:LSeg(E.$1,F.$1);
consider S being Function of NAT, bool REAL such that
A45: for i being Nat holds S.i = F(i) from LambdaD;
  set AA = LSeg(e,f) /\ Upper_Arc C,
      BB = LSeg(e,f) /\ Lower_Arc C;
    AA is compact & BB is compact by COMPTS_1:20;
  then reconsider A = proj2.:AA, B = proj2.:BB as compact Subset of REAL
      by JORDAN1A:28;
A46: A misses B
   proof assume A meets B;
    then consider z being set such that
A47:   z in A and
A48:   z in B by XBOOLE_0:3;
     reconsider z as Real by A47;
     consider p being Point of TOP-REAL 2 such that
A49:    p in AA and
A50:    z = proj2.p by A47,FUNCT_2:116;
     consider q being Point of TOP-REAL 2 such that
A51:    q in BB and
A52:    z = proj2.q by A48,FUNCT_2:116;
A53:   q in LSeg(e,f) by A51,XBOOLE_0:def 3;
A54:  p in LSeg(e,f) by A49,XBOOLE_0:def 3;
     then A55:    p`1 = s by A8,JORDAN6:34 .= q`1 by A8,A53,JORDAN6:34;
       p`2 = proj2.q by A50,A52,PSCOMP_1:def 29 .= q`2 by PSCOMP_1:def 29;
     then A56:      p = q by A55,TOPREAL3:11;
A57:   p in Upper_Arc C by A49,XBOOLE_0:def 3;
       q in Lower_Arc C by A51,XBOOLE_0:def 3;
     then p in Upper_Arc C /\ Lower_Arc C by A56,A57,XBOOLE_0:def 3;
     then A58:    p in {W-min C,E-max C } by JORDAN6:65;
     per cases by A58,TARSKI:def 2;
     suppose p = W-min C;
      then A59:     (W-min C)`1 = s by A8,A54,JORDAN6:34;
         (W-min C)`1 = W-bound C by PSCOMP_1:84;
      hence contradiction by A12,A59,XCMPLX_1:67;
      suppose p = E-max C;
       then A60:      (E-max C)`1 = s by A8,A54,JORDAN6:34;
         (E-max C)`1 = E-bound C by PSCOMP_1:104;
      hence contradiction by A12,A60,XCMPLX_1:67;
   end;
    AA c= LSeg(e,f) by XBOOLE_1:17;
  then A61: A c= [.f1,e1.] by A44,RELAT_1:156;
    BB c= LSeg(e,f) by XBOOLE_1:17;
  then A62: B c= [.f1,e1.] by A44,RELAT_1:156;
    for i being Nat holds S.i qua Subset of REAL is connected &
   S.i meets A & S.i meets B
   proof let i be Nat;
A63:   S.i = proj2.:LSeg(E.i,F.i) by A45;
    hence S.i is connected by JCT_MISC:15;
    reconsider DD = LSeg(e,f) /\ Upper_Arc L~Cage(C,i+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
    reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
A64: E.i = |[s,Es.i]| by A14;
    then A65: (E.i)`1 = s by EUCLID:56;
A66:  X-SpanStart(C,i+1) = Center Gauge(C,i+1) by JORDAN1H:57;
A67: F.i = |[s,Fs.i]| by A16;
     then A68: (F.i)`1 = s by EUCLID:56;
A69:  LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),1),
           Gauge(C,i+1)*(Center Gauge(C,i+1),len Gauge(C,i+1)))
          meets Upper_Arc L~Cage(C,i+1) by JORDAN1B:34;
       1 <= i+1 by NAT_1:29;
     then LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),1),
           Gauge(C,i+1)*(Center Gauge(C,i+1),len Gauge(C,i+1))) c=
      LSeg(Gauge(C,1)*(Center Gauge(C,1),1),
           Gauge(C,1)*(Center Gauge(C,1),len Gauge(C,1))) by JORDAN1A:65;
     then A70:  LSeg(f,e) meets Upper_Arc L~Cage(C,i+1) by A1,A69,XBOOLE_1:63;
       DD c= the carrier of TOP-REAL 2;
     then DD c= dom proj2 by FUNCT_2:def 1;
     then A71:    dom proj2 /\ DD = DD by XBOOLE_1:28;
       DD <> {} by A70,XBOOLE_0:def 7;
     then dom proj2 meets DD by A71,XBOOLE_0:def 7;
     then A72:    D <> {} by RELAT_1:151;
       Es.i = inf D by A13;
     then Es.i in D by A72,RCOMP_1:32;
     then consider dd being Point of TOP-REAL 2 such that
A73:   dd in DD and
A74:  Es.i = proj2.dd by FUNCT_2:116;
A75:  dd in LSeg(f,e) by A73,XBOOLE_0:def 3;
     then A76:   dd`1 = (E.i)`1 by A8,A65,JORDAN6:34;
     A77: (E.i)`2 = Es.i by A64,EUCLID:56
            .= dd`2 by A74,PSCOMP_1:def 29;
     then A78:    E.i in LSeg(e,f) by A75,A76,TOPREAL3:11;
       f in LSeg(e,f) by TOPREAL1:6;
     then A79:    LSeg(f,E.i) c= LSeg(e,f) by A78,TOPREAL1:12;
     reconsider DD = LSeg(f,E.i) /\ Lower_Arc L~Cage(C,i+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
     reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
     (E.i)`2 = Es.i by A64,EUCLID:56
          .= inf(proj2.:(LSeg(f,e) /\ Upper_Arc L~Cage(C,i+1))) by A13;
     then consider j such that
A80:    1 <= j and
A81:    j <= width Gauge(C,i+1) and
A82:    E.i = Gauge(C,i+1)*(X-SpanStart(C,i+1),j)
        by A1,A9,A65,A66,JORDAN1F:13;
A83:  E.i in Upper_Arc L~Cage(C,i+1) by A17;
     then A84:   LSeg(f,E.i)
          meets Lower_Arc L~Cage(C,i+1) by A1,A66,A80,A81,A82,JORDAN1J:62;
       DD c= the carrier of TOP-REAL 2;
     then DD c= dom proj2 by FUNCT_2:def 1;
     then A85:    dom proj2 /\ DD = DD by XBOOLE_1:28;
       DD <> {} by A84,XBOOLE_0:def 7;
     then dom proj2 meets DD by A85,XBOOLE_0:def 7;
     then A86:    D <> {} by RELAT_1:151;
       Fs.i = sup D by A15;
     then Fs.i in D by A86,RCOMP_1:32;
     then consider dd being Point of TOP-REAL 2 such that
A87:  dd in DD and
A88:  Fs.i = proj2.dd by FUNCT_2:116;
A89:  dd in LSeg(E.i,f) by A87,XBOOLE_0:def 3;
       E.i in Vertical_Line s by A65,JORDAN1A:17;
     then LSeg(E.i,f) c= Vertical_Line s by A6,JORDAN1A:23;
then A90:  dd`1 = (F.i)`1 by A68,A89,JORDAN6:34;
       (F.i)`2 = Fs.i by A67,EUCLID:56
            .= dd`2 by A88,PSCOMP_1:def 29;
then A91: F.i in LSeg(E.i,f) by A89,A90,TOPREAL3:11;
then A92:    LSeg(E.i,F.i) c= LSeg(e,f) by A78,A79,TOPREAL1:12;
       E.i in LSeg(E.i,f) by TOPREAL1:6;
then A93: LSeg(E.i,F.i) c= LSeg(E.i,f) by A91,TOPREAL1:12;
       (E.i)`2 = Es.i by A64,EUCLID:56
          .= inf(proj2.:(LSeg(f,e) /\ Upper_Arc L~Cage(C,i+1))) by A13;
     then consider j such that
A94:   1 <= j and
A95:   j <= width Gauge(C,i+1) and
A96:   E.i = Gauge(C,i+1)*(X-SpanStart(C,i+1),j)
      by A1,A9,A65,A66,JORDAN1F:13;
      i+1 >= 0+1 by NAT_1:29;
then A97: i+1 > 0 by NAT_1:38;
A98:  (F.i)`2 =Fs.i by A67,EUCLID:56
       .= sup(proj2.:(LSeg(f,E.i) /\ Lower_Arc L~Cage(C,i+1)))by A15;
     then consider k such that
A99:  1 <= k and
A100:  k <= width Gauge(C,i+1) and
A101:  F.i = Gauge(C,i+1)*(Center Gauge(C,i+1),k)
                     by A1,A66,A68,A83,A94,A95,A96,A97,JORDAN1I:30;
A102:  F.i in Lower_Arc L~Cage(C,i+1) by A28;
     A103: 1 <= Center Gauge(C,i+1) by JORDAN1B:12;
     A104: Center Gauge(C,i+1) <= len Gauge(C,i+1) by JORDAN1B:14;
      for p being real number st p in D holds p <= (E.i)`2
     proof let p be real number;
      assume p in D;
       then consider x being set such that
          x in dom proj2 and
A105:    x in DD and
A106:    p = proj2.x by FUNCT_1:def 12;
      reconsider x as Point of TOP-REAL 2 by A105;
A107:    f`2 <= (E.i)`2 by A10,A75,A77,TOPREAL1:10;
         x in LSeg(f,E.i) by A105,XBOOLE_0:def 3;
       then x`2 <= (E.i)`2 by A107,TOPREAL1:10;
      hence p <= (E.i)`2 by A106,PSCOMP_1:def 29;
     end;
    then A108: sup D <= (E.i)`2 by A86,PSCOMP_1:10;
then A109:  k <= j by A66,A94,A96,A98,A100,A101,A103,A104,GOBOARD5:5;
A110: for x be set holds
      x in LSeg(E.i,F.i) /\ Upper_Arc L~Cage(C,i+1) implies x = E.i
      proof
       reconsider DD = LSeg(f,e) /\ Upper_Arc L~Cage(C,i+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
       reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
       let x be set;
       assume
A111:      x in LSeg(E.i,F.i) /\ Upper_Arc L~Cage(C,i+1);
        then reconsider p = x as Point of TOP-REAL 2;
A112:      p in LSeg(E.i,F.i) by A111,XBOOLE_0:def 3;
        then A113:      p`1 = (E.i)`1 by A65,A68,GOBOARD7:5;
A114:      p`2 <= (E.i)`2 by A98,A108,A112,TOPREAL1:10;
          E.i = |[s,Es.i]| by A14;
then A115:       (E.i)`2 = Es.i by EUCLID:56
         .= inf D by A13;
          D is bounded by RCOMP_1:28;
then A116:     D is bounded_below by SEQ_4:def 3;
          p in Upper_Arc L~Cage(C,i+1) by A111,XBOOLE_0:def 3;
        then p in DD by A92,A112,XBOOLE_0:def 3;
        then proj2.p in D by FUNCT_2:43;
        then p`2 in D by PSCOMP_1:def 29;
        then (E.i)`2 <= p`2 by A115,A116,SEQ_4:def 5;
        then p`2 = (E.i)`2 by A114,AXIOMS:21;
       hence x = E.i by A113,TOPREAL3:11;
      end;
     A117: for x be set holds
      x in LSeg(E.i,F.i) /\ Lower_Arc L~Cage(C,i+1) implies x = F.i
      proof
       reconsider EE = LSeg(f,E.i) /\ Lower_Arc L~Cage(C,i+1)
        as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
       reconsider E0 = proj2.:EE as compact Subset of REAL by JORDAN1A:28;
       let x be set;
       assume
A118:      x in LSeg(E.i,F.i) /\ Lower_Arc L~Cage(C,i+1);
        then reconsider p = x as Point of TOP-REAL 2;
A119:      p in LSeg(E.i,F.i) by A118,XBOOLE_0:def 3;
then A120:      p`1 = (F.i)`1 by A65,A68,GOBOARD7:5;
A121:      p`2 >= (F.i)`2 by A98,A108,A119,TOPREAL1:10;
          F.i = |[s,Fs.i]| by A16;
then A122:         (F.i)`2 = Fs.i by EUCLID:56
           .= sup E0 by A15;
            E0 is bounded by RCOMP_1:28;
then A123:       E0 is bounded_above by SEQ_4:def 3;
            p in Lower_Arc L~Cage(C,i+1) by A118,XBOOLE_0:def 3;
          then p in EE by A93,A119,XBOOLE_0:def 3;
          then proj2.p in E0 by FUNCT_2:43;
          then p`2 in E0 by PSCOMP_1:def 29;
          then (F.i)`2 >= p`2 by A122,A123,SEQ_4:def 4;
          then p`2 = (F.i)`2 by A121,AXIOMS:21;
         hence x = F.i by A120,TOPREAL3:11;
        end;
A124: Gauge(C,i+1)*(Center Gauge(C,i+1),j) in
       LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
            Gauge(C,i+1)*(Center Gauge(C,i+1),j)) &
      Gauge(C,i+1)*(Center Gauge(C,i+1),k) in
       LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
            Gauge(C,i+1)*(Center Gauge(C,i+1),j)) by TOPREAL1:6;
A125: LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
       Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Upper_Arc L~Cage(C,i+1) =
       {Gauge(C,i+1)*(Center Gauge(C,i+1),j)}
   proof
    thus LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
     Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Upper_Arc L~Cage(C,i+1) c=
      {Gauge(C,i+1)*(Center Gauge(C,i+1),j)}
    proof
     let x be set;
     assume x in LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
      Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Upper_Arc L~Cage(C,i+1);
     then x = Gauge(C,i+1)*(Center Gauge(C,i+1),j) by A66,A96,A101,A110;
     hence x in {Gauge(C,i+1)*(Center Gauge(C,i+1),j)} by TARSKI:def 1;
    end;
     let x be set;
     assume x in {Gauge(C,i+1)*(Center Gauge(C,i+1),j)};
     then x = Gauge(C,i+1)*(Center Gauge(C,i+1),j) by TARSKI:def 1;
     hence x in LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
      Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Upper_Arc L~Cage(C,i+1)
       by A66,A83,A96,A124,XBOOLE_0:def 3;
   end;
   A126: LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
       Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Lower_Arc L~Cage(C,i+1) =
       {Gauge(C,i+1)*(Center Gauge(C,i+1),k)}
   proof
    thus LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
     Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Lower_Arc L~Cage(C,i+1) c=
      {Gauge(C,i+1)*(Center Gauge(C,i+1),k)}
    proof
     let x be set;
     assume x in LSeg(Gauge(C,i+1)*(Center Gauge(C,i+1),k),
      Gauge(C,i+1)*(Center Gauge(C,i+1),j)) /\ Lower_Arc L~Cage(C,i+1);
     then x = Gauge(C,i+1)*(Center Gauge(C,i+1),k) by A66,A96,A101,A117;
     hence x in {Gauge(C,i+1)*(Center Gauge(C,i+1),k)} by TARSKI:def 1;
    end;
     let x be set;
     assume x in {Gauge(C,i+1)*(Center Gauge(C,i+1),k)};
     then x = Gauge(C,i+1)*(Center Gauge(C,i+1),k) by TARSKI:def 1;
     hence thesis by A101,A102,A124,XBOOLE_0:def 3;
   end;
     then LSeg(F.i,E.i) meets Upper_Arc C
      by A66,A95,A96,A99,A101,A109,A125,JORDAN1J:64;
     then LSeg(E.i,F.i) meets AA by A92,XBOOLE_1:77;
    hence S.i meets A by A63,JORDAN1A:24;
       LSeg(E.i,F.i) meets Lower_Arc C
      by A66,A95,A96,A99,A101,A109,A125,A126,JORDAN1J:63;
     then LSeg(E.i,F.i) meets BB by A92,XBOOLE_1:77;
    hence S.i meets B by A63,JORDAN1A:24;
   end;
  then consider r being real number such that
A127: r in [.f1,e1.] and
A128: not r in A \/ B and
A129: for i being Nat ex k being Nat st i <= k & r in S.k
        by A46,A61,A62,JCT_MISC:21;
  reconsider r as Real by XREAL_0:def 1;
  set p = |[s,r]|;
A130: p in LSeg(e,f) by A5,A7,A127,JORDAN1A:21;
A131: p`1 = s by EUCLID:56;
A132: now assume p in C;
      then p in Lower_Arc C \/ Upper_Arc C by JORDAN6:65;
      then p in (Lower_Arc C \/ Upper_Arc C) /\ LSeg(e,f) by A130,XBOOLE_0:def
3;
      then p in AA \/ BB by XBOOLE_1:23;
      then proj2.p in proj2.:(AA \/ BB) by FUNCT_2:43;
      then r in proj2.:(AA \/ BB) by JORDAN1A:20;
     hence contradiction by A128,RELAT_1:153;
  end;
A133: meet BDD-Family C = C \/ BDD C by JORDAN10:21;
    for Y being set st Y in BDD-Family C holds p in Y
   proof let Y be set;
A134: BDD-Family C = { Cl BDD L~Cage(C,k1) where k1 is Nat : not contradiction
}
     by JORDAN10:def 2;
    assume Y in BDD-Family C;
     then consider k1 being Nat such that
A135:    Y = Cl BDD L~Cage(C,k1) by A134;
     consider k0 being Nat such that
A136:   k1 <= k0 and
A137:   r in S.k0 by A129;
A138: E.k0 = |[s,Es.k0]| by A14;
    then A139: (E.k0)`1 = s by EUCLID:56;
A140: F.k0 = |[s,Fs.k0]| by A16;
     then A141: (F.k0)`1 = s by EUCLID:56;
A142: proj2.(E.k0) = (E.k0)`2 & proj2.(F.k0) = (F.k0)`2 by PSCOMP_1:def 29;
    reconsider DD = LSeg(f,E.k0) /\ Lower_Arc L~Cage(C,k0+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
    reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
A143:  X-SpanStart(C,k0+1) = Center Gauge(C,k0+1) by JORDAN1H:57;
        (E.k0)`2 = Es.k0 by A138,EUCLID:56
          .= inf(proj2.:(LSeg(f,e) /\ Upper_Arc L~Cage(C,k0+1))) by A13;
      then consider j such that
A144:    1 <= j and
A145:    j <= width Gauge(C,k0+1) and
A146:    E.k0 = Gauge(C,k0+1)*(X-SpanStart(C,k0+1),j)
                     by A1,A9,A139,A143,JORDAN1F:13;
        E.k0 in Upper_Arc L~Cage(C,k0+1) by A17;
      then A147:   LSeg(f,E.k0)
          meets Lower_Arc L~Cage(C,k0+1) by A1,A143,A144,A145,A146,JORDAN1J:62;
      DD c= the carrier of TOP-REAL 2;
    then DD c= dom proj2 by FUNCT_2:def 1;
    then A148:  dom proj2 /\ DD = DD by XBOOLE_1:28;
      DD <> {} by A147,XBOOLE_0:def 7;
    then dom proj2 meets DD by A148,XBOOLE_0:def 7;
    then A149:  D <> {} by RELAT_1:151;
      Fs.k0 = sup D by A15;
    then Fs.k0 in D by A149,RCOMP_1:32;
    then consider dd being Point of TOP-REAL 2 such that
A150:  dd in DD and
A151:  Fs.k0 = proj2.dd by FUNCT_2:116;
A152: dd in LSeg(E.k0,f) by A150,XBOOLE_0:def 3;
      E.k0 in Vertical_Line s by A139,JORDAN1A:17;
    then LSeg(E.k0,f) c= Vertical_Line s by A6,JORDAN1A:23;
    then A153:  dd`1 = (F.k0)`1 by A141,A152,JORDAN6:34;
    A154: (F.k0)`2 = Fs.k0 by A140,EUCLID:56
            .= dd`2 by A151,PSCOMP_1:def 29;
    then A155:  F.k0 in LSeg(E.k0,f) by A152,A153,TOPREAL3:11;
    reconsider DD = LSeg(f,e) /\ Upper_Arc L~Cage(C,k0+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
    reconsider D = proj2.:DD as compact Subset of REAL by JORDAN1A:28;
A156:  LSeg(Gauge(C,k0+1)*(Center Gauge(C,k0+1),1),
           Gauge(C,k0+1)*(Center Gauge(C,k0+1),len Gauge(C,k0+1)))
          meets Upper_Arc L~Cage(C,k0+1) by JORDAN1B:34;
        1+0 <= k0+1 by NAT_1:29;
      then LSeg(Gauge(C,k0+1)*(Center Gauge(C,k0+1),1),
           Gauge(C,k0+1)*(Center Gauge(C,k0+1),len Gauge(C,k0+1))) c=
      LSeg(Gauge(C,1)*(Center Gauge(C,1),1),
           Gauge(C,1)*(Center Gauge(C,1),len Gauge(C,1))) by JORDAN1A:65;
      then A157:  LSeg(f,e) meets Upper_Arc L~Cage(C,k0+1) by A1,A156,XBOOLE_1:
63;
      DD c= the carrier of TOP-REAL 2;
    then DD c= dom proj2 by FUNCT_2:def 1;
    then A158:  dom proj2 /\ DD = DD by XBOOLE_1:28;
      DD <> {} by A157,XBOOLE_0:def 7;
    then dom proj2 meets DD by A158,XBOOLE_0:def 7;
    then A159:  D <> {} by RELAT_1:151;
      Es.k0 = inf D by A13;
    then Es.k0 in D by A159,RCOMP_1:32;
    then consider dd being Point of TOP-REAL 2 such that
A160:  dd in DD and
A161:  Es.k0 = proj2.dd by FUNCT_2:116;
A162: dd in LSeg(f,e) by A160,XBOOLE_0:def 3;
    then A163:  dd`1 = (E.k0)`1 by A8,A139,JORDAN6:34;
    A164: (E.k0)`2 = Es.k0 by A138,EUCLID:56
            .= dd`2 by A161,PSCOMP_1:def 29;
    then A165:    E.k0 in LSeg(f,e) by A162,A163,TOPREAL3:11;
    A166:   f`2 <= (E.k0)`2 by A10,A162,A164,TOPREAL1:10;
    then A167: (F.k0)`2 <= (E.k0)`2 by A152,A154,TOPREAL1:10;
      r in proj2.:LSeg(E.k0,F.k0) by A45,A137;
    then r in [.proj2.(F.k0),proj2.(E.k0).] by A142,A167,SPRECT_1:61;
    then A168:    p in LSeg(E.k0,F.k0) by A139,A141,JORDAN1A:21;
      (E.k0)`2 = Es.k0 by A138,EUCLID:56
          .= inf(proj2.:(LSeg(f,e) /\ Upper_Arc L~Cage(C,k0+1))) by A13;
    then consider j such that
A169:  1 <= j and
A170:  j <= width Gauge(C,k0+1) and
A171:  E.k0 = Gauge(C,k0+1)*(X-SpanStart(C,k0+1),j)
      by A1,A9,A139,A143,JORDAN1F:13;
A172:   E.k0 in Upper_Arc L~Cage(C,k0+1) by A17;
A173:   F.k0 in Lower_Arc L~Cage(C,k0+1) by A28;
       k0+1 >= 0+1 by NAT_1:29;
     then A174: k0+1 > 0 by NAT_1:38;
A175: (F.k0)`2 =Fs.k0 by A140,EUCLID:56
       .= sup(proj2.:(LSeg(f,E.k0) /\ Lower_Arc L~Cage(C,k0+1)))by A15;
    then consider k such that
A176:  1 <= k and
A177:  k <= width Gauge(C,k0+1) and
A178:  F.k0 = Gauge(C,k0+1)*(X-SpanStart(C,k0+1),k)
            by A1,A141,A143,A169,A170,A171,A172,A174,JORDAN1I:30;
    reconsider CC = LSeg(f,E.k0) /\ Lower_Arc L~Cage(C,k0+1)
         as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
    reconsider W = proj2.:CC as compact Subset of REAL by JORDAN1A:28;
       CC c= the carrier of TOP-REAL 2;
     then CC c= dom proj2 by FUNCT_2:def 1;
     then A179:    dom proj2 /\ CC = CC by XBOOLE_1:28;
       CC <> {} by A147,XBOOLE_0:def 7;
     then dom proj2 meets CC by A179,XBOOLE_0:def 7;
     then A180:    W <> {} by RELAT_1:151;
A181: 1 <= Center Gauge(C,k0+1) by JORDAN1B:12;
A182: Center Gauge(C,k0+1) <= len Gauge(C,k0+1) by JORDAN1B:14;
      for p being real number st p in W holds p <= (E.k0)`2
     proof let p be real number;
      assume p in W;
       then consider x being set such that
          x in dom proj2 and
A183:    x in CC and
A184:    p = proj2.x by FUNCT_1:def 12;
      reconsider x as Point of TOP-REAL 2 by A183;
         x in LSeg(f,E.k0) by A183,XBOOLE_0:def 3;
       then x`2 <= (E.k0)`2 by A166,TOPREAL1:10;
      hence p <= (E.k0)`2 by A184,PSCOMP_1:def 29;
     end;
    then sup W <= (E.k0)`2 by A180,PSCOMP_1:10;
    then A185:  k <= j by A143,A169,A171,A175,A177,A178,A181,A182,GOBOARD5:5;
    A186: E.k0 in LSeg(f,E.k0) by TOPREAL1:6;
    then A187: LSeg(E.k0,F.k0) c= LSeg(f,E.k0) by A155,TOPREAL1:12;
      f in LSeg(f,e) by TOPREAL1:6;
    then LSeg(f,E.k0) c= LSeg(e,f) by A165,TOPREAL1:12;
    then A188: LSeg(E.k0,F.k0) c= LSeg(e,f) by A155,A186,TOPREAL1:12;
     for x being set holds
    x in LSeg(E.k0,F.k0) /\ Upper_Arc L~Cage(C,k0+1) iff x = E.k0
    proof let x be set;
     thus x in LSeg(E.k0,F.k0) /\ Upper_Arc L~Cage(C,k0+1) implies x = E.k0
      proof assume
A189:      x in LSeg(E.k0,F.k0) /\ Upper_Arc L~Cage(C,k0+1);
        then reconsider p = x as Point of TOP-REAL 2;
A190:      p in LSeg(E.k0,F.k0) by A189,XBOOLE_0:def 3;
        then A191:      p`1 = (E.k0)`1 by A139,A141,GOBOARD7:5;
A192:      p`2 <= (E.k0)`2 by A167,A190,TOPREAL1:10;
          E.k0 = |[s,Es.k0]| by A14;
        then A193:       (E.k0)`2 = Es.k0 by EUCLID:56
         .= inf D by A13;
          D is bounded by RCOMP_1:28;
        then A194:     D is bounded_below by SEQ_4:def 3;
          p in Upper_Arc L~Cage(C,k0+1) by A189,XBOOLE_0:def 3;
        then p in DD by A188,A190,XBOOLE_0:def 3;
        then proj2.p in D by FUNCT_2:43;
        then p`2 in D by PSCOMP_1:def 29;
        then (E.k0)`2 <= p`2 by A193,A194,SEQ_4:def 5;
        then p`2 = (E.k0)`2 by A192,AXIOMS:21;
       hence x = E.k0 by A191,TOPREAL3:11;
      end;
     assume
A195:     x = E.k0;
      then x in LSeg(E.k0,F.k0) by TOPREAL1:6;
     hence x in LSeg(E.k0,F.k0) /\ Upper_Arc L~Cage(C,k0+1)
       by A172,A195,XBOOLE_0:def 3;
    end;
   then A196: LSeg(E.k0,F.k0) /\ Upper_Arc L~Cage(C,k0+1) = {E.k0} by TARSKI:
def 1;
   reconsider EE = LSeg(f,E.k0) /\ Lower_Arc L~Cage(C,k0+1)
        as compact Subset of TOP-REAL 2 by PSCOMP_1:64;
   reconsider E0 = proj2.:EE as compact Subset of REAL by JORDAN1A:28;
     for x being set holds
    x in LSeg(E.k0,F.k0) /\ Lower_Arc L~Cage(C,k0+1) iff x = F.k0
    proof let x be set;
     thus x in LSeg(E.k0,F.k0) /\ Lower_Arc L~Cage(C,k0+1) implies x = F.k0
      proof assume
A197:      x in LSeg(E.k0,F.k0) /\ Lower_Arc L~Cage(C,k0+1);
        then reconsider p = x as Point of TOP-REAL 2;
A198:      p in LSeg(E.k0,F.k0) by A197,XBOOLE_0:def 3;
        then A199:      p`1 = (F.k0)`1 by A139,A141,GOBOARD7:5;
A200:      p`2 >= (F.k0)`2 by A167,A198,TOPREAL1:10;
          F.k0 = |[s,Fs.k0]| by A16;
          then A201:         (F.k0)`2 = Fs.k0 by EUCLID:56
           .= sup E0 by A15;
            E0 is bounded by RCOMP_1:28;
          then A202:       E0 is bounded_above by SEQ_4:def 3;
            p in Lower_Arc L~Cage(C,k0+1) by A197,XBOOLE_0:def 3;
          then p in EE by A187,A198,XBOOLE_0:def 3;
          then proj2.p in E0 by FUNCT_2:43;
          then p`2 in E0 by PSCOMP_1:def 29;
          then (F.k0)`2 >= p`2 by A201,A202,SEQ_4:def 4;
          then p`2 = (F.k0)`2 by A200,AXIOMS:21;
         hence x = F.k0 by A199,TOPREAL3:11;
        end;
       assume
A203:       x = F.k0;
        then x in LSeg(E.k0,F.k0) by TOPREAL1:6;
       hence x in LSeg(E.k0,F.k0) /\ Lower_Arc L~Cage(C,k0+1)
           by A173,A203,XBOOLE_0:def 3;
      end;
     then LSeg(E.k0,F.k0) /\ Lower_Arc L~Cage(C,k0+1) = {F.k0} by TARSKI:def 1
;
     then LSeg(E.k0,F.k0) c= Cl RightComp Cage(C,k0+1)
            by A143,A169,A170,A171,A174,A176,A177,A178,A185,A196,Lm1;
     then A204:   p in Cl RightComp Cage(C,k0+1) by A168;
       k0 <= k0+1 by NAT_1:29;
     then A205:  RightComp Cage(C,k0+1) c= RightComp Cage(C,k0) by JORDAN1H:56;
       RightComp Cage(C,k0) c= RightComp Cage(C,k1) by A136,JORDAN1H:56;
     then RightComp Cage(C,k0+1) c= RightComp Cage(C,k1) by A205,XBOOLE_1:1;
     then Cl RightComp Cage(C,k0+1) c= Cl RightComp Cage(C,k1) by PRE_TOPC:49;
     then p in Cl RightComp Cage(C,k1) by A204;
    hence p in Y by A135,GOBRD14:47;
   end;
  then p in meet BDD-Family C by SETFAM_1:def 1;
  then p in BDD C by A132,A133,XBOOLE_0:def 2;
  then consider n,i,j such that
A206: 1 < i and
A207: i < len Gauge(C,n) and
A208: 1 < j and
A209: j < width Gauge(C,n) and
A210: p`1 <> (Gauge(C,n)*(i,j))`1 and
A211: p in cell(Gauge(C,n),i,j) and
A212: cell(Gauge(C,n),i,j) c= BDD C by JORDAN1C:35;
 take n,j;
 thus j < width Gauge(C,n) by A209;
      n >= 0+1 by A207,A209,A212,JORDAN1B:44;
    then A213: n > 0 by NAT_1:38;
A214:  X-SpanStart(C,n) = Center Gauge(C,n) by JORDAN1H:57;
      2 <= X-SpanStart(C,n) by JORDAN1H:58;
    then A215: 1 <= X-SpanStart(C,n) & X-SpanStart(C,n) <= len Gauge(C,n)
              by AXIOMS:22,JORDAN1H:58;
   4 <= len Gauge (C,1) by JORDAN8:13;
 then A216: 1 <= len Gauge (C,1) by AXIOMS:22;
  len Gauge(C,n) = width Gauge(C,n) by JORDAN8:def 1;
    then (Gauge(C,n)*(X-SpanStart(C,n),j))`1
          = s by A1,A5,A208,A209,A213,A214,A216,JORDAN1A:57;
 hence cell(Gauge(C,n),X-SpanStart(C,n)-'1,j) c= BDD C
          by A131,A206,A207,A208,A209,A210,A211,A212,A215,JORDAN1B:23;
end;

definition let C;
 func ApproxIndex C -> Nat means
:Def1: it is_sufficiently_large_for C &
  for j st j is_sufficiently_large_for C holds j >= it;
 existence
  proof
    defpred P[Nat] means $1 is_sufficiently_large_for C;
    set X = {i : P[i]};
    consider i such that
A1:    i is_sufficiently_large_for C by Lm2;
A2:  i in X by A1;
      X is Subset of NAT from SubsetD;
    then reconsider X as non empty Subset of NAT by A2;
   take min X;
      min X in X by CQC_SIM1:def 8;
    then ex i st i = min X & i is_sufficiently_large_for C;
   hence min X is_sufficiently_large_for C;
   let j;
   assume j is_sufficiently_large_for C;
    then j in X;
   hence j >= min X by CQC_SIM1:def 8;
  end;
 uniqueness
  proof let it1,it2 be Nat such that
A3: it1 is_sufficiently_large_for C and
A4: for j st j is_sufficiently_large_for C holds j >= it1 and
A5: it2 is_sufficiently_large_for C and
A6: for j st j is_sufficiently_large_for C holds j >= it2;
      it1 <= it2 & it2 <= it1 by A3,A4,A5,A6;
   hence it1 = it2 by AXIOMS:21;
  end;
end;

theorem Th1:
 ApproxIndex C >= 1
proof
    ApproxIndex C is_sufficiently_large_for C by Def1;
 hence thesis by JORDAN1H:60;
end;

definition let C;
 func Y-InitStart C -> Nat means
:Def2: it < width Gauge(C,ApproxIndex C) &
    cell(Gauge(C,ApproxIndex C),X-SpanStart(C,ApproxIndex C)-'1,it) c= BDD C &
  for j st j < width Gauge(C,ApproxIndex C) &
       cell(Gauge(C,ApproxIndex C),X-SpanStart(C,ApproxIndex C)-'1,j) c= BDD C
    holds j >= it;
 existence
  proof set n = ApproxIndex C;
    defpred P[Nat] means
      $1 < width Gauge(C,n) &
      cell(Gauge(C,n),X-SpanStart(C,n)-'1,$1) c= BDD C;
      n is_sufficiently_large_for C by Def1;
    then consider j such that
A1:   P[j] by JORDAN1H:def 3;
    set X = { i: P[i] };
A2:  j in X by A1;
      X is Subset of NAT from SubsetD;
    then reconsider X as non empty Subset of NAT by A2;
   take min X;
      min X in X by CQC_SIM1:def 8;
    then ex i st i = min X & P[i];
   hence P[min X];
   let i;
   assume P[i];
    then i in X;
   hence thesis by CQC_SIM1:def 8;
  end;
 uniqueness
  proof let it1,it2 be Nat;
   assume
     it1 < width Gauge(C,ApproxIndex C) &
    cell(Gauge(C,ApproxIndex C),X-SpanStart(C,ApproxIndex C)-'1,it1) c= BDD C &
  (for j st j < width Gauge(C,ApproxIndex C) &
       cell(Gauge(C,ApproxIndex C),X-SpanStart(C,ApproxIndex C)-'1,j) c= BDD C
    holds j >= it1) &
   it2 < width Gauge(C,ApproxIndex C) &
    cell(Gauge(C,ApproxIndex C),X-SpanStart(C,ApproxIndex C)-'1,it2) c= BDD C &
  for j st j < width Gauge(C,ApproxIndex C) &
       cell(Gauge(C,ApproxIndex C),X-SpanStart(C,ApproxIndex C)-'1,j) c= BDD C
    holds j >= it2;
    then it1 <= it2 & it2 <= it1;
   hence thesis by AXIOMS:21;
  end;
end;

theorem Th2:
 Y-InitStart C > 1
proof set m = ApproxIndex C;
A1: X-SpanStart(C,m)-'1 <= len Gauge(C,m) by JORDAN1H:59;
 assume
A2: Y-InitStart C <= 1;
  per cases by A2,CQC_THE1:2;
  suppose Y-InitStart C = 0;
  then A3: cell(Gauge(C,m),X-SpanStart(C,m)-'1,0) c= BDD C by Def2;
    0 <= width Gauge(C,m) by NAT_1:18;
  then A4: cell(Gauge(C,m),X-SpanStart(C,m)-'1,0) is non empty by A1,JORDAN1A:
45;
    cell(Gauge(C,m),X-SpanStart(C,m)-'1,0) c= UBD C by A1,JORDAN1A:70;
  then UBD C meets BDD C by A3,A4,XBOOLE_1:68;
 hence contradiction by JORDAN2C:28;
  suppose Y-InitStart C = 1;
   then A5:  cell(Gauge(C,m),X-SpanStart(C,m)-'1,1) c= BDD C by Def2;
    width Gauge(C,m) <> 0 by GOBOARD1:def 5;
  then A6: 0+1 <= width Gauge(C,m) by RLVECT_1:99;
  then A7: cell(Gauge(C,m),X-SpanStart(C,m)-'1,1) is non empty by A1,JORDAN1A:
45;
A8: cell(Gauge(C,m),X-SpanStart(C,m)-'1,0) c= UBD C by A1,JORDAN1A:70;
   set i1 = X-SpanStart(C,m);
A9: C is Bounded by JORDAN2C:73;
A10: i1 < len Gauge(C,m) by JORDAN1H:58;
      i1-'1 <= i1 by JORDAN3:7;
   then A11: i1-'1 < len Gauge(C,m) by A10,AXIOMS:22;
A12:  0 < width Gauge(C,m) by A6,NAT_1:38;
     1 <= i1-'1 by JORDAN1H:59;
   then cell(Gauge(C,m),i1-'1,0) /\ cell(Gauge(C,m),i1-'1,0+1)
    = LSeg(Gauge(C,m)*(i1-'1,0+1),Gauge(C,m)*(i1-'1+1,0+1))
              by A11,A12,GOBOARD5:27;
    then A13:   cell(Gauge(C,m),i1-'1,0) meets cell(Gauge(C,m),i1-'1,0+1) by
XBOOLE_0:def 7;
     ex B being Subset of TOP-REAL 2 st B is_outside_component_of C & B=UBD C
                          by A9,JORDAN2C:76;
   then A14:  UBD C is_a_component_of C` by JORDAN2C:def 4;
A15:  cell(Gauge(C,m),X-SpanStart(C,m)-'1,1) is connected by A6,A11,JORDAN1A:46
;
    BDD C c= C` by JORDAN2C:29;
  then cell(Gauge(C,m),X-SpanStart(C,m)-'1,1) c= C` by A5,XBOOLE_1:1;
  then cell(Gauge(C,m),X-SpanStart(C,m)-'1,1) c= UBD C by A8,A13,A14,A15,
GOBOARD9:6;
  then UBD C meets BDD C by A5,A7,XBOOLE_1:68;
 hence contradiction by JORDAN2C:28;
end;

theorem Th3:
 Y-InitStart C + 1 < width Gauge(C,ApproxIndex C)
proof set m = ApproxIndex C;
A1: X-SpanStart(C,m)-'1 <= len Gauge(C,m) by JORDAN1H:59;
 assume Y-InitStart C + 1 >= width Gauge(C,m);
  then A2: Y-InitStart C + 1 > width Gauge(C,m) or
    Y-InitStart C + 1 = width Gauge(C,m) by AXIOMS:21;
A3: Y-InitStart C < width Gauge(C,m) or
    Y-InitStart C = width Gauge(C,m) by Def2;
  per cases by A2,A3,NAT_1:38;
  suppose Y-InitStart C = width Gauge(C,m);
 hence contradiction by Def2;
  suppose Y-InitStart C + 1 = width Gauge(C,m);
   then Y-InitStart C = width Gauge(C,m)-'1 by BINARITH:39;
   then A4:  cell(Gauge(C,m),X-SpanStart(C,m)-'1,width Gauge(C,m)-'1) c= BDD C
by Def2;
    width Gauge(C,m)-'1 <= width Gauge(C,m) by JORDAN3:7;
  then A5: cell(Gauge(C,m),X-SpanStart(C,m)-'1,width Gauge(C,m)-'1) is non
empty
                                         by A1,JORDAN1A:45;
A6: cell(Gauge(C,m),X-SpanStart(C,m)-'1,width Gauge(C,m)) c= UBD C by A1,
JORDAN1A:71;
   set i1 = X-SpanStart(C,m);
A7: C is Bounded by JORDAN2C:73;
A8: i1 < len Gauge(C,m) by JORDAN1H:58;
    width Gauge(C,m) <> 0 by GOBOARD1:def 5;
then A9: 0+1 <= width Gauge(C,m) by RLVECT_1:99;
      i1-'1 <= i1 by JORDAN3:7;
then A10: i1-'1 < len Gauge(C,m) by A8,AXIOMS:22;
      width Gauge(C,m)-1 < width Gauge(C,m) by INT_1:26;
    then A11: width Gauge(C,m)-'1 < width Gauge(C,m) by A9,SCMFSA_7:3;
A12: width Gauge(C,m)-'1+1 = width Gauge(C,m) by A9,AMI_5:4;
     1 <= i1-'1 by JORDAN1H:59;
   then cell(Gauge(C,m),i1-'1,width Gauge(C,m)) /\
        cell(Gauge(C,m),i1-'1,width Gauge(C,m)-'1)
    = LSeg(Gauge(C,m)*(i1-'1,width Gauge(C,m)),
           Gauge(C,m)*(i1-'1+1,width Gauge(C,m))) by A10,A11,A12,GOBOARD5:27;
    then A13:   cell(Gauge(C,m),i1-'1,width Gauge(C,m)) meets
                cell(Gauge(C,m),i1-'1,width Gauge(C,m)-'1) by XBOOLE_0:def 7;
     ex B being Subset of TOP-REAL 2 st B is_outside_component_of C & B=UBD C
                          by A7,JORDAN2C:76;
   then A14:  UBD C is_a_component_of C` by JORDAN2C:def 4;
A15:  cell(Gauge(C,m),X-SpanStart(C,m)-'1,width Gauge(C,m)-'1) is connected
                              by A10,A11,JORDAN1A:46;
    BDD C c= C` by JORDAN2C:29;
  then cell(Gauge(C,m),X-SpanStart(C,m)-'1,width Gauge(C,m)-'1) c= C`
                               by A4,XBOOLE_1:1;
  then cell(Gauge(C,m),X-SpanStart(C,m)-'1,width Gauge(C,m)-'1)
                        c= UBD C by A6,A13,A14,A15,GOBOARD9:6;
  then UBD C meets BDD C by A4,A5,XBOOLE_1:68;
 hence contradiction by JORDAN2C:28;
end;

definition
  let C,n such that
A1: n is_sufficiently_large_for C;
A2: n >= ApproxIndex C by A1,Def1;
    set i1 = X-SpanStart(C,n);
 func Y-SpanStart(C,n) -> Nat means
:Def3: it <= width Gauge(C,n) &
   (for k st it <= k & k <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
     holds cell(Gauge(C,n),X-SpanStart(C,n)-'1,k) c= BDD C) &
    for j st j <= width Gauge(C,n) &
     for k st j <= k & k <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
       holds cell(Gauge(C,n),X-SpanStart(C,n)-'1,k) c= BDD C
    holds j >= it;
 existence
  proof
    set m = ApproxIndex C;
    defpred P[Nat] means
     $1 <= width Gauge(C,n) &
     for k st $1 <= k & k <= 2|^(n-'m)*(Y-InitStart C-'2)+2
      holds cell(Gauge(C,n),i1-'1,k) c= BDD C;
    set X = { i: P[i]};
A3:    1 < Y-InitStart C by Th2;
A4:    Y-InitStart C+1 < width Gauge(C,m) by Th3;
    set j0 = 2|^(n-'m)*(Y-InitStart C-'2)+2;
      Y-InitStart C + 1 < 2|^m + (2+1) by A4,JORDAN1A:49;
    then Y-InitStart C + 1 < 2|^m + 2 + 1 by XCMPLX_1:1;
    then A5:  Y-InitStart C < 2|^m + 2 by AXIOMS:24;
      1+1 <= Y-InitStart C by A3,NAT_1:38;
    then A6: Y-InitStart C-'2 < 2|^m by A5,SPRECT_3:7;
      2|^(n-'m) >= 1 by PREPOWER:19;
    then 2|^(n-'m) >= 0 by AXIOMS:22;
    then 2|^(n-'m)*(Y-InitStart C-'2) <= 2|^(n-'m)*(2|^m) by A6,AXIOMS:25;
    then 2|^(n-'m)*(Y-InitStart C-'2) <= 2|^((n-'m)+m) by NEWTON:13;
    then A7:  2|^(n-'m)*(Y-InitStart C-'2) <= 2|^n by A2,AMI_5:4;
      2|^n <= 2|^n + 1 by NAT_1:29;
    then 2|^(n-'m)*(Y-InitStart C-'2) <= 2|^n + 1 by A7,AXIOMS:22;
    then j0 <= 2|^n + 1+2 by AXIOMS:24;
    then j0 <= 2|^n + (1+2) by XCMPLX_1:1;
    then j0 <= len Gauge(C,n) by JORDAN8:def 1;
    then A8:  j0 <= width Gauge(C,n) by JORDAN8:def 1;
      now let j;
     assume j0 <= j & j <= 2|^(n-'m)*(Y-InitStart C-'2)+2;
      then A9:     j = j0 by AXIOMS:21;
A10:    X-SpanStart(C,m) = 2|^(m-'1) + 2 by JORDAN1H:def 2;
        1 <= 2|^(m-'1) by PREPOWER:19;
      then A11:    2+1 <= X-SpanStart(C,m) by A10,AXIOMS:24;
A12:   len Gauge(C,m) = 2|^m + (2 + 1) by JORDAN8:def 1
           .= 2|^m + 2 + 1 by XCMPLX_1:1;
        m-'1 <= m by GOBOARD9:2;
      then 2|^(m-'1) <= 2|^m by PCOMPS_2:4;
      then 2|^(m-'1) + 2 <= 2|^m + 2 by AXIOMS:24;
      then A13:    X-SpanStart(C,m) < len Gauge(C,m) by A10,A12,NAT_1:38;
A14:   m >= 1 by Th1;
      then A15:   n >= 1 by A2,AXIOMS:22;
        (n-'m)+(m-'1) = (n-'m)+(m-1) by A14,SCMFSA_7:3
        .= (n-'m)+ m-1 by XCMPLX_1:29
        .= n-1 by A2,AMI_5:4
        .= n-'1 by A15,SCMFSA_7:3;
      then 2|^(n-'1) = 2|^(n-'m)*(2|^(m-'1)) by NEWTON:13
            .= 2|^(n-'m)*(X-SpanStart(C,m)-2) by A10,XCMPLX_1:26;
      then A16:    i1 = 2|^(n-'m)*(X-SpanStart(C,m)-2)+2 by JORDAN1H:def 2;
        Y-InitStart C >= 1+1 by A3,NAT_1:38;
      then j = 2|^(n-'m)*(Y-InitStart C-2)+2 by A9,SCMFSA_7:3;
then A17:    cell(Gauge(C,n),i1-'1,j) c=
       cell(Gauge(C,m),X-SpanStart(C,m)-'1,Y-InitStart C)
          by A2,A3,A4,A11,A13,A16,JORDAN1A:69;
        cell(Gauge(C,m),X-SpanStart(C,m)-'1,Y-InitStart C) c= BDD C by Def2;
     hence cell(Gauge(C,n),i1-'1,j) c= BDD C by A17,XBOOLE_1:1;
    end;
    then A18:  j0 in X by A8;
      X is Subset of NAT from SubsetD;
    then reconsider X as non empty Subset of NAT by A18;
   take min X;
      min X in X by CQC_SIM1:def 8;
    then ex j st j = min X & P[j];
   hence P[min X];
   let j;
   assume P[j];
    then j in X;
   hence thesis by CQC_SIM1:def 8;
  end;
 uniqueness
  proof
    defpred definiens[Nat] means
   $1 <= width Gauge(C,n) &
  (for i st $1 <= i & i <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
   holds cell(Gauge(C,n),X-SpanStart(C,n)-'1,i) c= BDD C) &
  for j st j <= width Gauge(C,n) &
    for i st j <= i & i <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
       holds cell(Gauge(C,n),X-SpanStart(C,n)-'1,i) c= BDD C
    holds j >= $1;
   let it1,it2 be Nat;
   assume definiens[it1] & definiens[it2];
    then it1 <= it2 & it2 <= it1;
   hence thesis by AXIOMS:21;
  end;
end;

theorem Th4:
 n is_sufficiently_large_for C implies
 X-SpanStart(C,n) = 2|^(n-'ApproxIndex C)*(X-SpanStart(C,ApproxIndex C)-2)+2
 proof
   set i1 = X-SpanStart(C,n), m = ApproxIndex C;
A1:    X-SpanStart(C,m) = 2|^(m-'1) + 2 by JORDAN1H:def 2;
 assume n is_sufficiently_large_for C;
  then A2: n >=ApproxIndex C by Def1;
A3:   m >= 1 by Th1;
      then A4:   n >= 1 by A2,AXIOMS:22;
        (n-'m)+(m-'1) = (n-'m)+(m-1) by A3,SCMFSA_7:3
        .= (n-'m)+ m-1 by XCMPLX_1:29
        .= n-1 by A2,AMI_5:4
        .= n-'1 by A4,SCMFSA_7:3;
      then 2|^(n-'1) = 2|^(n-'m)*(2|^(m-'1)) by NEWTON:13
            .= 2|^(n-'m)*(X-SpanStart(C,m)-2) by A1,XCMPLX_1:26;
   hence i1 = 2|^(n-'m)*(X-SpanStart(C,m)-2)+2 by JORDAN1H:def 2;
  end;

theorem Th5:
 n is_sufficiently_large_for C implies
  Y-SpanStart(C,n) <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
proof set m = ApproxIndex C;
A1: X-SpanStart(C,m) > 2 by JORDAN1H:58;
 assume
A2: n is_sufficiently_large_for C;
  then A3: n >=ApproxIndex C by Def1;
  set i1 = X-SpanStart(C,n);
    set j0 = 2|^(n-'m)*(Y-InitStart C-'2)+2;
A4: Y-InitStart C+1 < width Gauge(C,m) by Th3;
A5: 1 < Y-InitStart C by Th2;
   then 1+1 <= Y-InitStart C by NAT_1:38;
   then A6: Y-InitStart C-'2 = Y-InitStart C-2 by SCMFSA_7:3;
     Y-InitStart C < Y-InitStart C +1 by REAL_1:69;
   then Y-InitStart C < width Gauge(C,m) by A4,AXIOMS:22;
   then A7:  j0 <= width Gauge(C,n) by A3,A5,A6,JORDAN1A:53;
      now let j;
     assume j0 <= j & j <= 2|^(n-'m)*(Y-InitStart C-'2)+2;
      then A8:     j = j0 by AXIOMS:21;
A9:   cell(Gauge(C,m),X-SpanStart(C,m)-'1,Y-InitStart C) c= BDD C by Def2;
A10:   2+1 <= X-SpanStart(C,m) by A1,NAT_1:38;
A11:   len Gauge(C,m) = 2|^m + 3 by JORDAN8:def 1;
A12:   X-SpanStart(C,m) = 2|^(m-'1) + 2 by JORDAN1H:def 2;
       m-'1 <= m by JORDAN3:7;
     then 2|^(m-'1) <= 2|^m by PCOMPS_2:4;
     then A13:    X-SpanStart(C,m) < len Gauge(C,m) by A11,A12,REAL_1:67;
       i1 = 2|^(n-'m)*(X-SpanStart(C,m)-2)+2 by A2,Th4;
     then cell(Gauge(C,n),i1-'1,j) c=
       cell(Gauge(C,m),X-SpanStart(C,m)-'1,Y-InitStart C)
        by A3,A4,A5,A6,A8,A10,A13,JORDAN1A:69;
     hence cell(Gauge(C,n),i1-'1,j) c= BDD C by A9,XBOOLE_1:1;
    end;
 hence Y-SpanStart(C,n) <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
    by A2,A7,Def3;
end;

theorem Th6:
 n is_sufficiently_large_for C
  implies cell(Gauge(C,n),X-SpanStart(C,n)-'1,Y-SpanStart(C,n)) c= BDD C
proof assume
A1: n is_sufficiently_large_for C;
 then Y-SpanStart(C,n) <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2 by Th5;
 hence thesis by A1,Def3;
end;

theorem Th7:
 n is_sufficiently_large_for C implies
 1 < Y-SpanStart(C,n) & Y-SpanStart(C,n) <= width Gauge(C,n)
proof
 assume
A1: n is_sufficiently_large_for C;
 thus 1 < Y-SpanStart(C,n)
  proof
  A2: X-SpanStart(C,n)-'1 <= len Gauge(C,n) by JORDAN1H:59;
   assume
  A3: Y-SpanStart(C,n) <= 1;
    per cases by A3,CQC_THE1:2;
    suppose Y-SpanStart(C,n) = 0;
    then A4: cell(Gauge(C,n),X-SpanStart(C,n)-'1,0) c= BDD C by A1,Th6;
      0 <= width Gauge(C,n) by NAT_1:18;
    then A5: cell(Gauge(C,n),X-SpanStart(C,n)-'1,0) is non empty by A2,JORDAN1A
:45;
      cell(Gauge(C,n),X-SpanStart(C,n)-'1,0) c= UBD C by A2,JORDAN1A:70;
    then UBD C meets BDD C by A4,A5,XBOOLE_1:68;
   hence contradiction by JORDAN2C:28;
    suppose Y-SpanStart(C,n) = 1;
     then A6:  cell(Gauge(C,n),X-SpanStart(C,n)-'1,1) c= BDD C by A1,Th6;
      width Gauge(C,n) <> 0 by GOBOARD1:def 5;
    then A7: 0+1 <= width Gauge(C,n) by RLVECT_1:99;
    then A8: cell(Gauge(C,n),X-SpanStart(C,n)-'1,1) is non empty by A2,JORDAN1A
:45;
  A9: cell(Gauge(C,n),X-SpanStart(C,n)-'1,0) c= UBD C by A2,JORDAN1A:70;
     set i1 = X-SpanStart(C,n);
  A10: C is Bounded by JORDAN2C:73;
  A11: i1 < len Gauge(C,n) by JORDAN1H:58;
        i1-'1 <= i1 by JORDAN3:7;
     then A12: i1-'1 < len Gauge(C,n) by A11,AXIOMS:22;
  A13:  0 < width Gauge(C,n) by A7,NAT_1:38;
       1 <= i1-'1 by JORDAN1H:59;
     then cell(Gauge(C,n),i1-'1,0) /\ cell(Gauge(C,n),i1-'1,0+1)
      = LSeg(Gauge(C,n)*(i1-'1,0+1),Gauge(C,n)*(i1-'1+1,0+1))
                by A12,A13,GOBOARD5:27;
      then A14:   cell(Gauge(C,n),i1-'1,0) meets cell(Gauge(C,n),i1-'1,0+1)
      by XBOOLE_0:def 7;
       ex B being Subset of TOP-REAL 2 st B is_outside_component_of C & B=UBD C
                            by A10,JORDAN2C:76;
     then A15:  UBD C is_a_component_of C` by JORDAN2C:def 4;
A16:  cell(Gauge(C,n),X-SpanStart(C,n)-'1,1) is connected by A7,A12,JORDAN1A:46
;
      BDD C c= C` by JORDAN2C:29;
    then cell(Gauge(C,n),X-SpanStart(C,n)-'1,1) c= C` by A6,XBOOLE_1:1;
    then cell(Gauge(C,n),X-SpanStart(C,n)-'1,1) c= UBD C by A9,A14,A15,A16,
GOBOARD9:6;
    then UBD C meets BDD C by A6,A8,XBOOLE_1:68;
   hence contradiction by JORDAN2C:28;
  end;
 thus Y-SpanStart(C,n) <= width Gauge(C,n) by A1,Def3;
end;

theorem
   n is_sufficiently_large_for C implies
 [X-SpanStart(C,n),Y-SpanStart(C,n)] in Indices Gauge(C,n)
proof
 assume
A1: n is_sufficiently_large_for C;
     1+1 < X-SpanStart(C,n) by JORDAN1H:58;
then A2: 1 < X-SpanStart(C,n) & X-SpanStart(C,n) < len Gauge(C,n) by JORDAN1H:
58,NAT_1:38;
    1 < Y-SpanStart(C,n) & Y-SpanStart(C,n) <= width Gauge(C,n) by A1,Th7;
 hence thesis by A2,GOBOARD7:10;
end;

theorem
   n is_sufficiently_large_for C implies
 [X-SpanStart(C,n)-'1,Y-SpanStart(C,n)] in Indices Gauge(C,n)
proof
 assume
A1: n is_sufficiently_large_for C;
A2: 1 <= X-SpanStart(C,n)-'1 & X-SpanStart(C,n)-'1 < len Gauge(C,n) by JORDAN1H
:59;
    1 < Y-SpanStart(C,n) & Y-SpanStart(C,n) <= width Gauge(C,n) by A1,Th7;
 hence thesis by A2,GOBOARD7:10;
end;

theorem
   n is_sufficiently_large_for C
  implies cell(Gauge(C,n),X-SpanStart(C,n)-'1,Y-SpanStart(C,n)-'1) meets C
proof
 assume
A1: n is_sufficiently_large_for C;
  set i1 = X-SpanStart(C,n);
A2: Y-SpanStart(C,n) <= width Gauge(C,n) by A1,Def3;
 assume A3: cell(Gauge(C,n),X-SpanStart(C,n)-'1,Y-SpanStart(C,n)-'1) misses C;
A4: Y-SpanStart(C,n)-'1 <= width Gauge(C,n) by A2,JORDAN3:7;
A5: 1 < Y-SpanStart(C,n) by A1,Th7;
    for k st Y-SpanStart(C,n)-'1 <= k &
     k <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2
    holds cell(Gauge(C,n),i1-'1,k) c= BDD C
   proof let k such that
A6:  Y-SpanStart(C,n)-'1 <= k and
A7:  k <= 2|^(n-'ApproxIndex C)*(Y-InitStart C-'2)+2;
    per cases by A6,AXIOMS:21;
    suppose
A8:   Y-SpanStart(C,n)-'1 = k;
     then A9:    cell(Gauge(C,n),i1-'1,k) c= C` by A3,SUBSET_1:43;
A10: i1 < len Gauge(C,n) by JORDAN1H:58;
      i1-'1 <= i1 by JORDAN3:7;
   then A11: i1-'1 < len Gauge(C,n) by A10,AXIOMS:22;
A12:  1 < Y-SpanStart(C,n) & Y-SpanStart(C,n) <= width Gauge(C,n) by A1,Th7;
    then A13:   k+1 = Y-SpanStart(C,n) by A8,AMI_5:4;
      k < k+1 by REAL_1:69;
    then A14:  k < width Gauge(C,n) by A12,A13,AXIOMS:22;
     1+1 < X-SpanStart(C,n) by JORDAN1H:58;
   then 1 <= i1-1 by REAL_1:84;
   then 1 <= i1-'1 by JORDAN3:1;
   then cell(Gauge(C,n),i1-'1,k) /\ cell(Gauge(C,n),i1-'1,k+1)
    = LSeg(Gauge(C,n)*(i1-'1,k+1),Gauge(C,n)*(i1-'1+1,k+1))
              by A11,A14,GOBOARD5:27;
    then A15:   cell(Gauge(C,n),i1-'1,k) meets cell(Gauge(C,n),i1-'1,k+1) by
XBOOLE_0:def 7;
      cell(Gauge(C,n),i1-'1,k+1) c= BDD C by A1,A13,Th6;
    then A16:  cell(Gauge(C,n),i1-'1,k) meets BDD C by A15,XBOOLE_1:63;
    set W = {B where B is Subset of TOP-REAL 2: B is_inside_component_of C};
A17:  BDD C = union W by JORDAN2C:def 5;
    then consider e being set such that
A18: e in W and
A19: cell(Gauge(C,n),i1-'1,k) meets e by A16,ZFMISC_1:98;
    consider B being Subset of TOP-REAL 2 such that
A20: e = B and
A21: B is_inside_component_of C by A18;
A22:   cell(Gauge(C,n),i1-'1,k) is connected by A11,A14,JORDAN1A:46;
       B is_a_component_of C` by A21,JORDAN2C:def 3;
     then A23:    cell(Gauge(C,n),i1-'1,k) c= B by A9,A19,A20,A22,GOBOARD9:6;
       B c= BDD C by A17,A18,A20,ZFMISC_1:92;
    hence cell(Gauge(C,n),i1-'1,k) c= BDD C by A23,XBOOLE_1:1;
    suppose Y-SpanStart(C,n)-'1 < k;
     then Y-SpanStart(C,n) < k+1 by SPRECT_3:8;
     then Y-SpanStart(C,n) <= k by NAT_1:38;
    hence cell(Gauge(C,n),i1-'1,k) c= BDD C by A1,A7,Def3;
   end;
  then A24:  Y-SpanStart(C,n)-'1 >=Y-SpanStart(C,n) by A1,A4,Def3;
     Y-SpanStart(C,n)-1 < Y-SpanStart(C,n) by INT_1:26;
 hence contradiction by A5,A24,SCMFSA_7:3;
end;

theorem
   n is_sufficiently_large_for C
 implies cell(Gauge(C,n),X-SpanStart(C,n)-'1,Y-SpanStart(C,n)) misses C
proof assume n is_sufficiently_large_for C;
  then A1: cell(Gauge(C,n),X-SpanStart(C,n)-'1,Y-SpanStart(C,n)) c= BDD C by
Th6;
    BDD C misses C by JORDAN1A:15;
 hence thesis by A1,XBOOLE_1:63;
end;


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