:: On a Dividing Function of the Simple Closed Curve into Segments :: by Yatsuka Nakamura :: :: Received June 16, 1998 :: Copyright (c) 1998-2012 Association of Mizar Users :: (Stowarzyszenie Uzytkownikow Mizara, Bialystok, Poland). :: This code can be distributed under the GNU General Public Licence :: version 3.0 or later, or the Creative Commons Attribution-ShareAlike :: License version 3.0 or later, subject to the binding interpretation :: detailed in file COPYING.interpretation. :: See COPYING.GPL and COPYING.CC-BY-SA for the full text of these :: licenses, or see http://www.gnu.org/licenses/gpl.html and :: http://creativecommons.org/licenses/by-sa/3.0/. environ vocabularies NUMBERS, PRE_TOPC, EUCLID, ARYTM_1, SUBSET_1, XXREAL_0, ARYTM_3, RCOMP_1, XBOOLE_0, TOPREAL2, PSCOMP_1, JORDAN6, TOPREAL1, JORDAN3, TARSKI, FUNCT_1, BORSUK_1, RELAT_1, TOPS_2, ORDINAL2, STRUCT_0, FINSEQ_1, CARD_1, XXREAL_1, REAL_1, PARTFUN1, MEASURE5, GOBRD10, ORDINAL4; notations TARSKI, XBOOLE_0, SUBSET_1, NUMBERS, REAL_1, NAT_1, RCOMP_1, NAT_D, FINSEQ_1, FUNCT_1, RELSET_1, PARTFUN1, SEQ_1, VALUED_0, TOPREAL1, TOPREAL2, TBSP_1, GOBRD10, PRE_TOPC, TOPS_2, FINSEQ_6, STRUCT_0, COMPTS_1, EUCLID, PSCOMP_1, JORDAN5C, JORDAN6, TOPMETR, XXREAL_0; constructors REAL_1, RCOMP_1, NAT_D, TOPS_2, COMPTS_1, TBSP_1, TOPMETR, TOPREAL1, PSCOMP_1, GOBRD10, SEQ_1, JORDAN5C, JORDAN6, XXREAL_2, FINSEQ_6; registrations XBOOLE_0, RELSET_1, XXREAL_0, XREAL_0, MEMBERED, STRUCT_0, PRE_TOPC, EUCLID, TOPREAL1, BORSUK_2, VALUED_0, COMPTS_1, XXREAL_2, FINSEQ_1, FUNCT_1; requirements REAL, SUBSET, BOOLE, NUMERALS, ARITHM; definitions TARSKI, XBOOLE_0, FUNCT_1, STRUCT_0; theorems TARSKI, JORDAN6, TOPREAL1, TOPREAL5, JORDAN5C, UNIFORM1, PRE_TOPC, FUNCT_2, TOPS_2, RELAT_1, FUNCT_1, FINSEQ_1, FINSEQ_2, NAT_1, FINSEQ_4, GOBRD10, SPRECT_1, XBOOLE_0, XBOOLE_1, FINSEQ_3, BORSUK_1, COMPTS_1, RELSET_1, JORDAN5B, PARTFUN2, XCMPLX_1, XREAL_1, XXREAL_0, PARTFUN1, XXREAL_1, XXREAL_2, SEQM_3, NAT_D, XREAL_0, FINSEQ_6; schemes DOMAIN_1, NAT_1; begin :: Definition of the Segment and its property reserve p,p1,p2,p3,q for Point of TOP-REAL 2; Lm1: 2-'1 = 2-1 by XREAL_1:233 .=1; Lm2: for i, j, k be Element of NAT holds i-'k <= j implies i <= j + k proof let i, j, k be Element of NAT; assume A1: i-'k <= j; per cases; suppose A2: i >= k; i-'k +k <= j + k by A1,XREAL_1:6; hence thesis by A2,XREAL_1:235; end; suppose A3: i <= k; k <= j + k by NAT_1:11; hence thesis by A3,XXREAL_0:2; end; end; Lm3: for i, j, k be Element of NAT holds j + k <= i implies k <= i -' j proof let i, j, k be Element of NAT; assume A1: j + k <= i; per cases by A1,XXREAL_0:1; suppose j + k = i; hence thesis by NAT_D:34; end; suppose j + k < i; hence thesis by Lm2; end; end; theorem Th1: for P being compact non empty Subset of TOP-REAL 2 st P is being_simple_closed_curve holds W-min(P) in Lower_Arc(P) & E-max(P) in Lower_Arc(P) & W-min(P) in Upper_Arc(P) & E-max(P) in Upper_Arc(P) proof let P be compact non empty Subset of TOP-REAL 2; assume P is being_simple_closed_curve; then Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) & Lower_Arc(P) is_an_arc_of E-max(P),W-min(P) by JORDAN6:50; hence thesis by TOPREAL1:1; end; theorem Th2: for P being compact non empty Subset of TOP-REAL 2,q st P is being_simple_closed_curve & LE q,W-min(P),P holds q=W-min(P) proof let P be compact non empty Subset of TOP-REAL 2,q; assume P is being_simple_closed_curve & LE q,W-min(P),P; then LE q,W-min(P),Upper_Arc(P),W-min(P),E-max(P) & Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by JORDAN6:def 8,def 10; hence thesis by JORDAN6:54; end; theorem Th3: for P being compact non empty Subset of TOP-REAL 2,q st P is being_simple_closed_curve & q in P holds LE W-min(P),q,P proof let P be compact non empty Subset of TOP-REAL 2,q; assume that A1: P is being_simple_closed_curve and A2: q in P; A3: q in Upper_Arc(P) \/ Lower_Arc(P) by A1,A2,JORDAN6:50; A4: Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by A1,JORDAN6:50; A5: W-min(P) in Upper_Arc(P) by A1,Th1; per cases by A3,XBOOLE_0:def 3; suppose A6: q in Upper_Arc(P); then LE W-min(P),q,Upper_Arc(P),W-min(P),E-max(P) by A4,JORDAN5C:10; hence thesis by A5,A6,JORDAN6:def 10; end; suppose A7: q in Lower_Arc(P); per cases; suppose not q=W-min(P); hence thesis by A5,A7,JORDAN6:def 10; end; suppose A8: q=W-min(P); then LE W-min(P),q,Upper_Arc(P),W-min(P),E-max(P) by A5,JORDAN5C:9; hence thesis by A5,A8,JORDAN6:def 10; end; end; end; definition let P be compact non empty Subset of TOP-REAL 2, q1,q2 be Point of TOP-REAL 2; func Segment(q1,q2,P) -> Subset of TOP-REAL 2 equals :Def1: {p: LE q1,p,P & LE p,q2,P} if q2<>W-min(P) otherwise {p1: LE q1,p1,P or q1 in P & p1=W-min(P)}; correctness proof ex B being Subset of TOP-REAL 2 st (q2<>W-min(P) implies B={p: LE q1,p ,P & LE p,q2,P})& (not q2<>W-min(P) implies B={p1: LE q1,p1,P or q1 in P & p1= W-min(P)}) proof per cases; suppose A1: q2<>W-min(P); defpred P[Point of TOP-REAL 2] means LE q1,$1,P & LE $1,q2,P; {p: P[p]} is Subset of TOP-REAL 2 from DOMAIN_1:sch 7; then reconsider C = {p: LE q1,p,P & LE p,q2,P} as Subset of TOP-REAL 2; q2<>W-min(P) implies C={p: LE q1,p,P & LE p,q2,P}; hence thesis by A1; end; suppose A2: not q2<>W-min(P); defpred P[Point of TOP-REAL 2] means LE q1,$1,P or q1 in P & $1=W-min( P); {p1: P[p1]} is Subset of TOP-REAL 2 from DOMAIN_1:sch 7; then reconsider C = {p1: LE q1,p1,P or q1 in P & p1=W-min(P)} as Subset of TOP-REAL 2; not q2<>W-min(P) implies C={p1: LE q1,p1,P or q1 in P & p1=W-min(P )}; hence thesis by A2; end; end; hence thesis; end; end; theorem for P being compact non empty Subset of TOP-REAL 2 st P is being_simple_closed_curve holds Segment(W-min(P),E-max(P),P)=Upper_Arc(P) & Segment(E-max(P),W-min(P),P)=Lower_Arc(P) proof let P be compact non empty Subset of TOP-REAL 2; assume A1: P is being_simple_closed_curve; then A2: Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by JORDAN6:def 8; A3: {p1: LE E-max(P),p1,P or E-max(P) in P & p1=W-min(P)} = Lower_Arc(P) proof A4: {p1: LE E-max(P),p1,P or E-max(P) in P & p1=W-min(P)} c= Lower_Arc(P) proof let x be set; assume x in {p1: LE E-max(P),p1,P or E-max(P) in P & p1=W-min(P)}; then consider p1 such that A5: p1=x and A6: LE E-max(P),p1,P or E-max(P) in P & p1=W-min(P); per cases by A6; suppose A7: LE E-max(P),p1,P; per cases by A5,A7,JORDAN6:def 10; suppose x in Lower_Arc(P); hence thesis; end; suppose A8: E-max(P) in Upper_Arc(P) & p1 in Upper_Arc(P) & LE E-max(P) ,p1,Upper_Arc(P),W-min(P),E-max(P); A9: Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by A1,JORDAN6:50; then LE p1,E-max(P),Upper_Arc(P),W-min(P),E-max(P) by A8,JORDAN5C:10; then A10: p1=E-max(P) by A8,A9,JORDAN5C:12; Lower_Arc(P) is_an_arc_of E-max(P),W-min(P) by A1,JORDAN6:def 9; hence thesis by A5,A10,TOPREAL1:1; end; end; suppose E-max(P) in P & p1=W-min(P); then x in {W-min(P),E-max(P)} by A5,TARSKI:def 2; then x in Upper_Arc(P) /\ Lower_Arc(P) by A1,JORDAN6:def 9; hence thesis by XBOOLE_0:def 4; end; end; Lower_Arc(P) c= {p1: LE E-max(P),p1,P or E-max(P) in P & p1=W-min(P) } proof let x be set; assume A11: x in Lower_Arc(P); then reconsider p2=x as Point of TOP-REAL 2; Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by A1,JORDAN6:50; then not (E-max P in P & p2=W-min P) implies E-max P in Upper_Arc P & p2 in Lower_Arc P & not p2=W-min P by A11,SPRECT_1:14,TOPREAL1:1; then LE E-max(P),p2,P or E-max P in P & p2=W-min P by JORDAN6:def 10; hence thesis; end; hence thesis by A4,XBOOLE_0:def 10; end; A12: E-max(P)<>W-min(P) by A1,TOPREAL5:19; {p: LE W-min(P),p,P & LE p,E-max(P),P} = Upper_Arc(P) proof A13: {p: LE W-min(P),p,P & LE p,E-max(P),P} c= Upper_Arc(P) proof let x be set; assume x in {p: LE W-min(P),p,P & LE p,E-max(P),P}; then consider p such that A14: p=x and LE W-min(P),p,P and A15: LE p,E-max(P),P; per cases by A15,JORDAN6:def 10; suppose p in Upper_Arc(P) & E-max(P) in Lower_Arc(P) & not E-max(P)= W-min(P); hence thesis by A14; end; suppose p in Upper_Arc(P) & E-max(P) in Upper_Arc(P) & LE p,E-max(P), Upper_Arc(P),W-min(P),E-max(P); hence thesis by A14; end; suppose A16: p in Lower_Arc(P) & E-max(P) in Lower_Arc(P) & not E-max(P)= W-min(P) & LE p,E-max(P),Lower_Arc(P),E-max(P),W-min(P); Lower_Arc(P) is_an_arc_of E-max(P),W-min(P) by A1,JORDAN6:def 9; then p=E-max(P) by A16,JORDAN6:54; hence thesis by A2,A14,TOPREAL1:1; end; end; Upper_Arc(P) c= {p: LE W-min(P),p,P & LE p,E-max(P),P} proof let x be set; assume A17: x in Upper_Arc(P); then reconsider p2=x as Point of TOP-REAL 2; E-max(P) in Lower_Arc(P) by A1,Th1; then A18: LE p2,E-max(P),P by A12,A17,JORDAN6:def 10; A19: W-min(P) in Upper_Arc(P) by A1,Th1; LE W-min(P),p2,Upper_Arc(P),W-min(P),E-max(P) by A2,A17,JORDAN5C:10; then LE W-min(P),p2,P by A17,A19,JORDAN6:def 10; hence thesis by A18; end; hence thesis by A13,XBOOLE_0:def 10; end; hence thesis by A12,A3,Def1; end; theorem Th5: for P being compact non empty Subset of TOP-REAL 2, q1,q2 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P holds q1 in P & q2 in P proof let P be compact non empty Subset of TOP-REAL 2, q1,q2 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P; A3: Upper_Arc(P) \/ Lower_Arc(P)=P by A1,JORDAN6:50; per cases by A2,JORDAN6:def 10; suppose q1 in Upper_Arc(P) & q2 in Lower_Arc(P); hence thesis by A3,XBOOLE_0:def 3; end; suppose q1 in Upper_Arc(P) & q2 in Upper_Arc(P); hence thesis by A3,XBOOLE_0:def 3; end; suppose q1 in Lower_Arc(P) & q2 in Lower_Arc(P); hence thesis by A3,XBOOLE_0:def 3; end; end; theorem Th6: for P being compact non empty Subset of TOP-REAL 2, q1,q2 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P holds q1 in Segment(q1,q2,P) & q2 in Segment(q1,q2,P) proof let P be compact non empty Subset of TOP-REAL 2, q1,q2 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P; hereby per cases; suppose A3: q2<>W-min(P); q1 in P by A1,A2,Th5; then LE q1,q1,P by A1,JORDAN6:56; then q1 in {p: LE q1,p,P & LE p,q2,P} by A2; hence q1 in Segment(q1,q2,P) by A3,Def1; end; suppose A4: q2=W-min(P); q1 in P by A1,A2,Th5; then LE q1,q1,P by A1,JORDAN6:56; then q1 in {p1: LE q1,p1,P or q1 in P & p1=W-min(P)}; hence q1 in Segment(q1,q2,P) by A4,Def1; end; end; per cases; suppose A5: q2<>W-min(P); q2 in P by A1,A2,Th5; then LE q2,q2,P by A1,JORDAN6:56; then q2 in {p: LE q1,p,P & LE p,q2,P} by A2; hence thesis by A5,Def1; end; suppose A6: q2=W-min(P); q2 in {p1: LE q1,p1,P or q1 in P & p1=W-min(P)} by A2; hence thesis by A6,Def1; end; end; theorem Th7: for P being compact non empty Subset of TOP-REAL 2, q1 being Point of TOP-REAL 2 st q1 in P & P is being_simple_closed_curve holds q1 in Segment(q1,W-min P,P) proof let P be compact non empty Subset of TOP-REAL 2, q1 be Point of TOP-REAL 2 such that A1: q1 in P; assume P is being_simple_closed_curve; then LE q1,q1,P by A1,JORDAN6:56; then q1 in {p1: LE q1,p1,P or q1 in P & p1=W-min(P)}; hence thesis by Def1; end; theorem for P being compact non empty Subset of TOP-REAL 2, q being Point of TOP-REAL 2 st P is being_simple_closed_curve & q in P & q<>W-min(P) holds Segment(q,q,P)={q} proof let P be compact non empty Subset of TOP-REAL 2, q be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: q in P and A3: q <> W-min P; for x being set holds x in Segment(q,q,P) iff x=q proof let x be set; hereby assume x in Segment(q,q,P); then x in {p: LE q,p,P & LE p,q,P} by A3,Def1; then ex p st p=x & LE q,p,P & LE p,q,P; hence x=q by A1,JORDAN6:57; end; assume A4: x=q; LE q,q,P by A1,A2,JORDAN6:56; then x in {p: LE q,p,P & LE p,q,P} by A4; hence thesis by A3,Def1; end; hence thesis by TARSKI:def 1; end; theorem for P being compact non empty Subset of TOP-REAL 2, q1,q2 being Point of TOP-REAL 2 st P is being_simple_closed_curve & q1<>W-min(P) & q2<>W-min(P) holds not W-min(P) in Segment(q1,q2,P) proof let P be compact non empty Subset of TOP-REAL 2, q1,q2 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: q1<>W-min(P) and A3: q2<>W-min(P); A4: Segment(q1,q2,P)={p: LE q1,p,P & LE p,q2,P} by A3,Def1; now A5: Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by A1,JORDAN6:def 8; assume W-min(P) in Segment(q1,q2,P); then consider p such that A6: p=W-min(P) and A7: LE q1,p,P and LE p,q2,P by A4; LE q1,p,Upper_Arc(P),W-min(P),E-max(P) by A6,A7,JORDAN6:def 10; hence contradiction by A2,A6,A5,JORDAN6:54; end; hence thesis; end; theorem Th10: for P being compact non empty Subset of TOP-REAL 2, q1,q2,q3 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P & LE q2,q3,P & not(q1=q2 & q1=W-min(P)) & not(q2=q3 & q2=W-min(P)) holds Segment(q1, q2,P)/\ Segment(q2,q3,P)={q2} proof let P be compact non empty Subset of TOP-REAL 2, q1,q2,q3 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P and A3: LE q2,q3,P and A4: not(q1=q2 & q1=W-min(P)) and A5: not(q2=q3 & q2=W-min(P)); A6: Upper_Arc(P) is_an_arc_of W-min(P),E-max(P) by A1,JORDAN6:def 8; thus Segment(q1,q2,P)/\ Segment(q2,q3,P) c= {q2} proof let x be set; assume A7: x in Segment(q1,q2,P)/\ Segment(q2,q3,P); then A8: x in Segment(q2,q3,P) by XBOOLE_0:def 4; A9: x in Segment(q1,q2,P) by A7,XBOOLE_0:def 4; now per cases; case q3<>W-min(P); then x in {p: LE q2,p,P & LE p,q3,P} by A8,Def1; then A10: ex p st p=x & LE q2,p,P & LE p,q3,P; per cases; suppose q2<>W-min(P); then x in {p2: LE q1,p2,P & LE p2,q2,P} by A9,Def1; then ex p2 st p2=x & LE q1,p2,P & LE p2,q2,P; hence x=q2 by A1,A10,JORDAN6:57; end; suppose A11: q2=W-min(P); then LE q1,q2,Upper_Arc(P),W-min(P),E-max(P) by A2,JORDAN6:def 10; hence x=q2 by A4,A6,A11,JORDAN6:54; end; end; case A12: q3=W-min(P); then x in {p1: LE q2,p1,P or q2 in P & p1=W-min(P)} by A8,Def1; then consider p1 such that A13: p1=x and A14: LE q2,p1,P or q2 in P & p1=W-min(P); p1 in {p: LE q1,p,P & LE p,q2,P} by A5,A9,A12,A13,Def1; then ex p st p=p1 & LE q1,p,P & LE p,q2,P; hence x=q2 by A1,A3,A12,A13,A14,JORDAN6:57; end; end; hence thesis by TARSKI:def 1; end; let x be set; assume x in {q2}; then x=q2 by TARSKI:def 1; then x in Segment(q1,q2,P) & x in Segment(q2,q3,P) by A1,A2,A3,Th6; hence thesis by XBOOLE_0:def 4; end; theorem Th11: for P being compact non empty Subset of TOP-REAL 2, q1,q2 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P & q1 <> W-min P & q2 <> W-min P holds Segment(q1,q2,P)/\ Segment(q2,W-min P,P)={q2} proof let P be compact non empty Subset of TOP-REAL 2, q1,q2 be Point of TOP-REAL 2; set q3 = W-min P; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P and A3: q1<>q3 and A4: not q2=W-min(P); thus Segment(q1,q2,P)/\ Segment(q2,W-min P,P) c= {q2} proof let x be set; assume A5: x in Segment(q1,q2,P)/\ Segment(q2,q3,P); then x in Segment(q2,q3,P) by XBOOLE_0:def 4; then x in {p1: LE q2,p1,P or q2 in P & p1=W-min P} by Def1; then consider p1 such that A6: p1=x and A7: LE q2,p1,P or q2 in P & p1=W-min P; x in Segment(q1,q2,P) by A5,XBOOLE_0:def 4; then p1 in {p: LE q1,p,P & LE p,q2,P} by A4,A6,Def1; then A8: ex p st p=p1 & LE q1,p,P & LE p,q2,P; per cases by A7; suppose LE q2,p1,P; then x=q2 by A1,A6,A8,JORDAN6:57; hence thesis by TARSKI:def 1; end; suppose q2 in P & p1=W-min(P); hence thesis by A1,A3,A8,Th2; end; end; let x be set; assume x in {q2}; then A9: x=q2 by TARSKI:def 1; q2 in P by A1,A2,Th5; then A10: x in Segment(q2,q3,P) by A1,A9,Th7; x in Segment(q1,q2,P) by A1,A2,A9,Th6; hence thesis by A10,XBOOLE_0:def 4; end; theorem Th12: for P being compact non empty Subset of TOP-REAL 2, q1,q2 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P & q1<>q2 & q1<>W-min(P) holds Segment(q2,W-min(P),P)/\ Segment(W-min(P),q1,P)={W-min(P)} proof let P be compact non empty Subset of TOP-REAL 2, q1,q2 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P and A3: q1<>q2 and A4: q1<>W-min(P); thus Segment(q2,W-min(P),P)/\ Segment(W-min(P),q1,P) c= {W-min(P)} proof let x be set; assume A5: x in Segment(q2,W-min(P),P)/\ Segment(W-min(P),q1,P); then x in Segment(q2,W-min(P),P) by XBOOLE_0:def 4; then x in {p1: LE q2,p1,P or q2 in P & p1=W-min(P)} by Def1; then consider p1 such that A6: p1=x and A7: LE q2,p1,P or q2 in P & p1=W-min(P); A8: x in Segment(W-min(P),q1,P) by A5,XBOOLE_0:def 4; now per cases by A7; case A9: LE q2,p1,P; x in {p: LE W-min(P),p,P & LE p,q1,P} by A4,A8,Def1; then ex p2 st p2=x & LE W-min(P),p2,P & LE p2,q1,P; then LE q2,q1,P by A1,A6,A9,JORDAN6:58; hence contradiction by A1,A2,A3,JORDAN6:57; end; case q2 in P & p1=W-min(P); hence x=W-min(P) by A6; end; end; hence thesis by TARSKI:def 1; end; let x be set; assume x in {W-min(P)}; then A10: x=W-min(P) by TARSKI:def 1; q2 in P by A1,A2,Th5; then x in {p1: LE q2,p1,P or q2 in P & p1=W-min(P)} by A10; then A11: x in Segment(q2,W-min(P),P) by Def1; q1 in P by A1,A2,Th5; then LE W-min(P),q1,P by A1,Th3; then x in Segment(W-min(P),q1,P) by A1,A10,Th6; hence thesis by A11,XBOOLE_0:def 4; end; theorem Th13: for P being compact non empty Subset of TOP-REAL 2, q1,q2,q3,q4 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P & LE q2,q3,P & LE q3,q4,P & q1<>q2 & q2<>q3 holds Segment(q1,q2,P) misses Segment(q3 ,q4,P) proof let P be compact non empty Subset of TOP-REAL 2, q1,q2,q3,q4 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P and A3: LE q2,q3,P and A4: LE q3,q4,P and A5: q1<>q2 and A6: q2<>q3; set x = the Element of Segment(q1,q2,P)/\ Segment(q3,q4,P); assume A7: Segment(q1,q2,P)/\ Segment(q3,q4,P)<>{}; then A8: x in Segment(q1,q2,P) by XBOOLE_0:def 4; A9: x in Segment(q3,q4,P) by A7,XBOOLE_0:def 4; per cases; suppose q4=W-min(P); then q3=W-min(P) by A1,A4,Th2; hence contradiction by A1,A3,A6,Th2; end; suppose A10: q4<>W-min(P); q2<>W-min(P) by A1,A2,A5,Th2; then x in {p2: LE q1,p2,P & LE p2,q2,P} by A8,Def1; then A11: ex p2 st p2=x & LE q1,p2,P & LE p2,q2,P; x in {p1: LE q3,p1,P & LE p1,q4,P} by A9,A10,Def1; then ex p1 st p1=x & LE q3,p1,P & LE p1,q4,P; then LE q3,q2,P by A1,A11,JORDAN6:58; hence contradiction by A1,A3,A6,JORDAN6:57; end; end; theorem Th14: for P being compact non empty Subset of TOP-REAL 2, q1,q2,q3 being Point of TOP-REAL 2 st P is being_simple_closed_curve & LE q1,q2,P & LE q2,q3,P & q1<>W-min P & q2<>q3 holds Segment(q1,q2,P) misses Segment(q3,W-min P ,P) proof let P be compact non empty Subset of TOP-REAL 2, q1,q2,q3 be Point of TOP-REAL 2; assume that A1: P is being_simple_closed_curve and A2: LE q1,q2,P and A3: LE q2,q3,P and A4: q1<>W-min P and A5: q2<>q3; set x = the Element of Segment(q1,q2,P)/\ Segment(q3,W-min P,P); assume A6: Segment(q1,q2,P)/\ Segment(q3,W-min P,P)<>{}; then A7: x in Segment(q1,q2,P) by XBOOLE_0:def 4; x in Segment(q3,W-min P,P) by A6,XBOOLE_0:def 4; then x in {p1: LE q3,p1,P or q3 in P & p1=W-min P} by Def1; then A8: ex p1 st p1=x &( LE q3,p1,P or q3 in P & p1=W-min P); q2 <> W-min P by A1,A2,A4,Th2; then x in {p: LE q1,p,P & LE p,q2,P} by A7,Def1; then ex p3 st p3 = x & LE q1,p3,P & LE p3,q2,P; then LE q3,q2,P by A1,A4,A8,Th2,JORDAN6:58; hence contradiction by A1,A3,A5,JORDAN6:57; end; begin :: A function to divide the simple closed curve reserve n for Element of NAT; theorem Th15: for P being non empty Subset of TOP-REAL n, f being Function of I[01], (TOP-REAL n)|P st f is being_homeomorphism ex g being Function of I[01], TOP-REAL n st f=g & g is continuous & g is one-to-one proof let P be non empty Subset of TOP-REAL n, f be Function of I[01], (TOP-REAL n )|P; A1: [#]((TOP-REAL n)|P)= P by PRE_TOPC:def 5; the carrier of (TOP-REAL n)|P = [#]((TOP-REAL n)|P) .=P by PRE_TOPC:def 5; then reconsider g1=f as Function of I[01],TOP-REAL n by FUNCT_2:7; assume A2: f is being_homeomorphism; then A3: f is one-to-one by TOPS_2:def 5; A4: [#]((TOP-REAL n)|P) <> {} & f is continuous by A2,TOPS_2:def 5; A5: for P2 being Subset of TOP-REAL n st P2 is open holds g1"P2 is open proof let P2 be Subset of TOP-REAL n; reconsider B1=P2 /\ P as Subset of (TOP-REAL n)|P by A1,XBOOLE_1:17; f"(rng f) c= f"P by A1,RELAT_1:143; then A6: dom f c= f"P by RELAT_1:134; assume P2 is open; then B1 is open by A1,TOPS_2:24; then A7: f"B1 is open by A4,TOPS_2:43; f"P c= dom f by RELAT_1:132; then f"B1 = f"P2 /\ f"P & f"P=dom f by A6,FUNCT_1:68,XBOOLE_0:def 10; hence thesis by A7,RELAT_1:132,XBOOLE_1:28; end; [#]TOP-REAL n <> {}; then g1 is continuous by A5,TOPS_2:43; hence thesis by A3; end; theorem Th16: for P being non empty Subset of TOP-REAL n, g being Function of I[01], (TOP-REAL n) st g is continuous one-to-one & rng g = P ex f being Function of I[01],(TOP-REAL n)|P st f=g & f is being_homeomorphism proof let P be non empty Subset of TOP-REAL n, g be Function of I[01], TOP-REAL n; assume that A1: g is continuous one-to-one and A2: rng g = P; the carrier of (TOP-REAL n)|P = [#]((TOP-REAL n)|P); then A3: the carrier of (TOP-REAL n)|P = P by PRE_TOPC:def 5; then reconsider f=g as Function of I[01],(TOP-REAL n)|P by A2,FUNCT_2:6; take f; thus f = g; A4: [#]((TOP-REAL n)|P)= P by PRE_TOPC:def 5; A5: dom f = the carrier of I[01] by FUNCT_2:def 1 .= [#]I[01]; A6: [#]TOP-REAL n<>{}; for P2 being Subset of (TOP-REAL n)|P st P2 is open holds f"P2 is open proof let P2 be Subset of (TOP-REAL n)|P; assume P2 is open; then consider C being Subset of TOP-REAL n such that A7: C is open and A8: C /\ [#]((TOP-REAL n)|P) = P2 by TOPS_2:24; g"P = [#]I[01] by A3,A5,RELSET_1:22; then f"P2 = f"C /\ [#]I[01] by A4,A8,FUNCT_1:68 .= f"C by XBOOLE_1:28; hence thesis by A1,A6,A7,TOPS_2:43; end; then A9: f is continuous by A4,TOPS_2:43; rng f = [#]((TOP-REAL n)|P) by A2,PRE_TOPC:def 5; hence thesis by A1,A5,A9,COMPTS_1:17; end; Lm4: now let h2 be Element of NAT; h2 0 ex h being FinSequence of the carrier of TOP-REAL 2 st h.1=W-min(P) & h is one-to-one & 8<=len h & rng h c= P &(for i being Element of NAT st 1<=i & i 0; A3: Upper_Arc P is_an_arc_of W-min P, E-max P by A1,JORDAN6:def 8; then consider g1 being Function of I[01], TOP-REAL 2 such that A4: g1 is continuous one-to-one and A5: rng g1 = Upper_Arc P and A6: g1.0 = W-min P and A7: g1.1 = E-max P by Th17; consider h1 being FinSequence of REAL such that A8: h1.1=0 and A9: h1.len h1=1 and A10: 5<=len h1 and A11: rng h1 c= the carrier of I[01] and A12: h1 is increasing and A13: for i being Element of NAT,Q being Subset of I[01], W being Subset of Euclid 2 st 1<=i & i 1+1+1 by A39,A47,A36,A52,A55,A57,XXREAL_0:2; then A60: len h0-'1 > 1+1 by Lm2; then A61: 1len h1 by NAT_1:13; then A66: 1len h1; A93: 0+2<=ny-'len h11 +2 by XREAL_1:6; then A94: 1<=(ny-'len h11 +2-'1) by Lm1,NAT_D:42; len h1 +1<=ny by A92,NAT_1:13; then A95: len h1 +1-len h1<=ny-len h1 by XREAL_1:9; then 1<=ny-'len h11 by A39,A92,XREAL_1:233; then 1+1<=ny-'len h11+1+1-1 by XREAL_1:6; then A96: 2<=ny-'len h11+2-'1 by A93,Lm1,NAT_D:39,42; A97: ny-len h11=ny-'len h11 by A39,A92,XREAL_1:233; ny-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A85, XREAL_1:9; then A98: ny-'len h11+2<=len h2-2+2 by A39,A97,XREAL_1:6; then (ny-'len h11 +2-'1)<=len h21 by A47,NAT_D:44; then A99: (ny-'len h11 +2-'1) in dom h21 by A94,FINSEQ_3:25; ny-'len h11+2-1<=len h2-1 by A98,XREAL_1:9; then A100: ny-'len h11+2-'1<=len h2-1 by A93,Lm1,NAT_D:39,42; A101: ny<=len h11 + len (mid(h21,2,len h21 -'1)) by A85,FINSEQ_1:22; then A102: ny-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by XREAL_1:9 ; len h11+1<=ny by A39,A92,NAT_1:13; then A103: h0.ny=(mid(h21,2,len h21 -'1)).(ny -len h11) by A101,FINSEQ_1:23; then A104: h0.ny=h21.(ny-'len h11 +2-'1) by A39,A48,A56,A50,A54,A97,A102,A95, FINSEQ_6:118; then h0.ny in rng h21 by A99,FUNCT_1:def 3; then h0.ny in rng g2 by FUNCT_1:14; then h0.nx in Upper_Arc(P)/\ Lower_Arc(P) by A23,A81,A89,XBOOLE_0:def 4 ; then A105: h0.nx in {W-min(P),E-max(P)} by A1,JORDAN6:50; per cases by A105,TARSKI:def 2; suppose h0.nx=W-min(P); then h21.(ny-'len h11 +2-'1)=W-min(P) by A39,A48,A56,A50,A54,A81,A103 ,A97,A102,A95,FINSEQ_6:118; then len h21=(ny-'len h11 +2-'1) by A46,A47,A34,A35,A32,A99, FUNCT_1:def 4; then len h21+1<=len h21-1+1 by A47,A100,XREAL_1:6; then len h21+1-len h21<=len h21 -len h21 by XREAL_1:9; then len h21+1-len h21<=0; hence thesis; end; suppose h0.nx=E-max(P); then 1=(ny-'len h11 +2-'1) by A46,A76,A77,A32,A81,A104,A99, FUNCT_1:def 4; hence thesis by A96; end; end; end; suppose A106: nx>len h1; then len h1 +1<=nx by NAT_1:13; then A107: len h1 +1-len h1<=nx-len h1 by XREAL_1:9; then 1<=nx-'len h11 by A39,A106,XREAL_1:233; then A108: 1+1<=nx-'len h11+1+1-1 by XREAL_1:6; A109: nx<=len h11 + len (mid(h21,2,len h21 -'1)) by A83,FINSEQ_1:22; then A110: nx-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by XREAL_1:9; A111: nx-len h11=nx-'len h11 by A39,A106,XREAL_1:233; nx-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A83, XREAL_1:9; then A112: nx-'len h11+2<=len h2-2+2 by A39,A111,XREAL_1:6; then A113: nx-'len h11+2-1<=len h2-1 by XREAL_1:9; A114: (nx-'len h11 +2-'1)<=len h21 by A47,A112,NAT_D:44; A115: 0+2<=nx-'len h11 +2 by XREAL_1:6; then 1<=(nx-'len h11 +2-'1) by Lm1,NAT_D:42; then A116: (nx-'len h11 +2-'1) in dom h21 by A114,FINSEQ_3:25; len h11+1<=nx by A39,A106,NAT_1:13; then A117: h0.nx=(mid(h21,2,len h21 -'1)).(nx -len h11) by A109,FINSEQ_1:23; then A118: h0.nx=h21.(nx-'len h11 +2-'1) by A39,A48,A56,A50,A54,A111,A110,A107, FINSEQ_6:118; then h0.nx in rng h21 by A116,FUNCT_1:def 3; then A119: h0.nx in Lower_Arc(P) by A23,FUNCT_1:14; per cases; suppose ny<=len h1; then A120: ny in dom h1 by A84,FINSEQ_3:25; then A121: h1.ny in rng h1 by FUNCT_1:def 3; h0.ny=h11.ny by A38,A120,FINSEQ_1:def 7 .=g1.(h1.ny) by A38,A120,FUNCT_1:12; then h0.ny in rng g1 by A37,A121,FUNCT_1:def 3; then h0.ny in Upper_Arc(P)/\ Lower_Arc(P) by A5,A81,A119,XBOOLE_0:def 4 ; then A122: h0.ny in {W-min(P),E-max(P)} by A1,JORDAN6:50; A123: nx-'len h11+2-'1<=len h2-1 by A115,A113,Lm1,NAT_D:39,42; A124: 2<=nx-'len h11+2-'1 by A108,A115,Lm1,NAT_D:39,42; per cases by A122,TARSKI:def 2; suppose h0.ny=W-min(P); then len h21=(nx-'len h11 +2-'1) by A46,A47,A34,A35,A32,A81,A118,A116 ,FUNCT_1:def 4; then len h21+1<=len h21-1+1 by A47,A123,XREAL_1:6; then len h21+1-len h21<=len h21 -len h21 by XREAL_1:9; then len h21+1-len h21<=0; hence thesis; end; suppose h0.ny=E-max(P); then h21.(nx-'len h11 +2-'1)=E-max(P) by A39,A48,A56,A50,A54,A81,A117 ,A111,A110,A107,FINSEQ_6:118; then 1=(nx-'len h11 +2-'1) by A46,A76,A77,A32,A116,FUNCT_1:def 4; hence thesis by A124; end; end; suppose A125: ny>len h1; then A126: ny-len h11=ny-'len h11 by A39,XREAL_1:233; len h1 +1<=ny by A125,NAT_1:13; then A127: h0.ny=(mid(h21,2,len h21 -'1)).(ny -len h11) & len h1 +1-len h1 <=ny-len h1 by A39,A36,A85,FINSEQ_1:23,XREAL_1:9; 0+2<=ny-'len h11 +2 by XREAL_1:6; then A128: 1<=(ny-'len h11 +2-'1) by Lm1,NAT_D:42; ny-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A85, XREAL_1:9; then A129: h0.ny=h21.(ny-'len h11 +2-'1) by A39,A48,A56,A50,A54,A126,A127, FINSEQ_6:118; ny-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A85, XREAL_1:9; then ny-'len h11+2<=len h2-2+2 by A39,A126,XREAL_1:6; then (ny-'len h11 +2-'1)<=len h21 by A47,NAT_D:44; then (ny-'len h11 +2-'1) in dom h21 by A128,FINSEQ_3:25; then nx-'len h1+2-'1=ny-'len h1+2-'1 by A39,A32,A81,A118,A116,A129, FUNCT_1:def 4; then nx-'len h1+2-1=ny-'len h1+2-'1 by A39,A115,Lm1,NAT_D:39,42; then nx-'len h1+(2-1)=ny-'len h1+2-1 by A39,A128,NAT_D:39; then len h1+nx-len h1=len h1+(ny-len h1) by A39,A111,A126,XCMPLX_1:29; hence thesis; end; end; end; then A130: h0/.len h0 <> W-min P by A16,A72,A65,A74,A75,A67,FUNCT_1:def 4; A131: dom g2 = [.0,1.] by BORSUK_1:40,FUNCT_2:def 1; thus 8<=len h0 by A38,A47,A36,A52,A55,A57,A58,FINSEQ_3:29; rng (mid(h21,2,len h21 -'1)) c= rng h21 & rng (g2*h2) c= rng g2 by FINSEQ_6:119,RELAT_1:26; then rng (g1*h1) c= rng g1 & rng (mid(h21,2,len h21 -'1)) c= rng g2 by RELAT_1:26,XBOOLE_1:1; then rng h11 \/ rng (mid(h21,2,len h21 -'1)) c= Upper_Arc(P) \/ Lower_Arc(P ) by A5,A23,XBOOLE_1:13; then rng h0 c=Upper_Arc(P) \/ Lower_Arc(P) by FINSEQ_1:31; hence rng h0 c= P by A1,JORDAN6:def 9; A132: dom g1 =[.0,1.] by BORSUK_1:40,FUNCT_2:def 1; thus for i being Element of NAT st 1<=i & i=len h1; per cases by A152,XXREAL_0:1; suppose A153: i>len h1; then len h11+1<=i by A39,NAT_1:13; then A154: h0.i=(mid(h21,2,len h21 -'1)).(i -len h11) by A36,A134,FINSEQ_1:23; A155: i+1-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A135 ,XREAL_1:9; i+1>len h11 by A39,A153,NAT_1:13; then A156: i+1-len h11=i+1-'len h11 by XREAL_1:233; A157: len h1 +1<=i by A153,NAT_1:13; then A158: len h1 +1-len h1<=i-len h1 by XREAL_1:9; A159: i-len h11=i-'len h11 by A39,A153,XREAL_1:233; A160: len h1 +1<=i+1 by A157,NAT_1:13; then A161: len h1 +1-len h1<=i+1-len h1 by XREAL_1:9; then A162: 1 i+1-'len h11 +2-'1 by A28,A47,A196; then h0/.(i+1) <> W-min P by A46,A47,A34,A35,A32,A197,A196,A190,A194, FUNCT_1:def 4; hence thesis by A189,A190,A198,JORDAN6:def 10; end; end; end; A199: ilen h1; i in dom h0 by A202,A199,FINSEQ_3:25; then A214: h0/.i=h0.i by PARTFUN1:def 6; A215: i-len h11=i-'len h11 by A39,A213,XREAL_1:233; i-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A199, XREAL_1:9; then i-'len h11+2<=len h2-2+2 by A39,A215,XREAL_1:6; then A216: (i-'len h11 +2-'1)<=len h21 by A47,NAT_D:44; i-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A199, XREAL_1:9; then A217: i-'len h11+2<=len h2-2+2 by A39,A215,XREAL_1:6; set k=i-'len h11+2-'1; A218: i-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A199, XREAL_1:9; A219: 0+2<=i-'len h11 +2 by XREAL_1:6; then A220: i-'len h11+2-'1=i-'len h11+2-1 by Lm1,NAT_D:39,42; 1<=(i-'len h11 +2-'1) by A219,Lm1,NAT_D:42; then A221: k in dom h2 by A46,A216,FINSEQ_3:25; then h2.k in rng h2 by FUNCT_1:def 3; then A222: g2.(h2.k) in rng g2 by A131,A29,BORSUK_1:40,FUNCT_1:def 3; A223: len h1 +1<=i by A213,NAT_1:13; then h0.i=(mid(h21,2,len h21 -'1)).(i -len h11) & len h1 +1-len h1<=i- len h1 by A39,A36,A199,FINSEQ_1:23,XREAL_1:9; then A224: h0.i=h21.(i-'len h11 +2-'1) by A39,A48,A56,A50,A54,A215,A218,FINSEQ_6:118 ; then h0.i=g2.(h2.k) by A221,FUNCT_1:13; then h0.i in Upper_Arc(P) /\ Lower_Arc(P) by A23,A206,A212,A211,A214,A222 ,XBOOLE_0:def 4; then h0.i in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; then A225: h0.i=W-min(P) or h0.i=E-max(P)by TARSKI:def 2; len h11+1-len h11<=i-len h11 by A39,A223,XREAL_1:9; then 1<=i-'len h11 by NAT_D:39; then 1+2<=i-'len h11+2 by XREAL_1:6; then 1+2-1<=i-'len h11+2-1 by XREAL_1:9; then A226: 1len h1; 1+1 in dom h1 by A14,FINSEQ_3:25; then A239: h11.(1+1)=g1.(h1.(1+1)) by FUNCT_1:13; A240: i-len h11=i-'len h11 by A39,A238,XREAL_1:233; i+1-1<=len h1+(len h2-2)-1 by A39,A47,A36,A52,A55,A57,A200,XREAL_1:9; then i-len h11<=len h1+((len h2-2)-1)-len h11 by XREAL_1:9; then i-'len h11+2<=len h2-2-1+2 by A39,A240,XREAL_1:6; then A241: i-'len h11+2-1<=len h2-1-1 by XREAL_1:9; A242: len h1 +1<=i by A238,NAT_1:13; then A243: len h1 +1-len h1<=i-len h1 by XREAL_1:9; h1.(1+1) in rng h1 by A15,FUNCT_1:def 3; then A244: g1.(h1.(1+1)) in rng g1 by A132,A11,BORSUK_1:40,FUNCT_1:def 3; 0+2<=i-'len h11 +2 by XREAL_1:6; then A245: 2-'1<=(i-'len h11 +2-'1) by NAT_D:42; set k=i-'len h11+2-'1; 0+1<=i-'len h11+1+1-1 by XREAL_1:6; then A246: i-'len h11+2-'1=i-'len h11+2-1 by NAT_D:39; A247: i-len h11 <=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A199, XREAL_1:9; i-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A199, XREAL_1:9; then i-'len h11+2<=len h2-2+2 by A39,A240,XREAL_1:6; then i-'len h11 +2-'1<=len h21 by A47,NAT_D:44; then A248: (i-'len h11 +2-'1) in dom h21 by A245,Lm1,FINSEQ_3:25; A249: h0.i=(mid(h21,2,len h21 -'1)).(i -len h11) by A39,A36,A199,A242, FINSEQ_1:23; then h0.(i)=h21.(i-'len h11 +2-'1) by A39,A48,A56,A50,A54,A240,A247,A243, FINSEQ_6:118; then A250: h0.i=g2.(h2.k) by A46,A248,FUNCT_1:13; h2.k in rng h2 by A46,A248,FUNCT_1:def 3; then A251: h0.i in Lower_Arc(P) by A23,A131,A29,A250,BORSUK_1:40,FUNCT_1:def 3; 1<=i-len h11 by A38,A243,FINSEQ_3:29; then h0.i=h21.k by A48,A56,A50,A54,A240,A247,A249,FINSEQ_6:118; then h0/.i <> W-min P by A228,A46,A34,A35,A32,A204,A246,A248,A241, FUNCT_1:def 4; hence LE h0/.(1+1),h0/.i,P by A5,A204,A206,A41,A239,A244,A251, JORDAN6:def 10; end; end; A252: len h0-len h11=len h0-'len h11 by A39,A65,XREAL_1:233; then (len h0-'len h11 +2-'1)<=len h21 by A36,A52,A55,A57,NAT_D:44; then (len h0-'len h11 +2-'1) in dom h21 by A43,Lm1,FINSEQ_3:25; then A253: h21.k=g2.(h2.k) & h2.k in rng h2 by A46,FUNCT_1:13,def 3; h1.len h1 in dom g1 by A9,A69,XXREAL_1:1; then A254: len h1 in dom (g1*h1) by A45,FUNCT_1:11; then A255: h11.len h1=E-max(P) by A7,A9,FUNCT_1:12; A256: for i being Element of NAT st 1<=i & i+1<=len h0 holds LE h0/.i,h0/.(i +1),P & h0/.(i+1)<>W-min(P) & h0/.i<>h0/.(i+1) proof let i be Element of NAT such that A257: 1<=i and A258: i+1<=len h0; A259: i 1 & i+1 <> i by A257,NAT_1:13; A270: i in dom h1 by A257,A264,FINSEQ_3:25; then A271: h1.i in rng h1 by FUNCT_1:def 3; then A272: 0 <= (h1.i) & (h1.i) <= 1 by A11,BORSUK_1:40,XXREAL_1:1; A273: h0.(i+1)=h11.(i+1) by A39,A260,A265,FINSEQ_1:64; then A274: h0.(i+1)=g1.(h1.(i+1)) by A266,FUNCT_1:13; then A275: h0.(i+1) in Upper_Arc(P) by A5,A132,A11,A267,BORSUK_1:40,FUNCT_1:def 3; A276: h0.i=h11.i by A39,A257,A264,FINSEQ_1:64; then A277: g1.(h1.i) = h0/.i by A263,A270,FUNCT_1:13; g1.(h1.i) in rng g1 by A132,A11,A271,BORSUK_1:40,FUNCT_1:def 3; then A278: h0.i in Upper_Arc(P) by A5,A276,A270,FUNCT_1:13; h1.i=len h1; per cases by A279,XXREAL_0:1; suppose A280: i>len h1; i-len h11len h11 by A39,A280,NAT_1:13; then A282: i+1-len h11=i+1-'len h11 by XREAL_1:233; set j=i-'len h11+2-'1; A283: i+1-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A258 ,XREAL_1:9; A284: 0+2<=i-'len h11 +2 by XREAL_1:6; then A285: j+1=i-'len h11+(1+1)-1+1 by Lm1,NAT_D:39,42 .=i-'len h11+(1+1); A286: len h1 +1<=i by A280,NAT_1:13; then A287: len h1 +1-len h1<=i-len h1 by XREAL_1:9; i+1 in dom h0 by A258,A260,FINSEQ_3:25; then A288: h0/.(i+1)=h0.(i+1) by PARTFUN1:def 6; A289: len h1 +1<=i+1 by A286,NAT_1:13; then A290: len h1 +1-len h1<=i+1-len h1 by XREAL_1:9; then 1 W-min P by A46,A34,A35,A32,A295,A292,A281,A285,A297,A288, FUNCT_1:def 4; A307: h0.(i+1)=g2.(h2.(j+1)) by A292,A305,A297,FUNCT_1:13; then A308: h0/.(i+1) in Lower_Arc(P) by A23,A131,A29,A298,A288,BORSUK_1:40 ,FUNCT_1:def 3; A309: h2.j in rng h2 by A300,FUNCT_1:def 3; then A310: j < j+1 & h0/.i in Lower_Arc(P) by A23,A131,A29,A304,A302,BORSUK_1:40 ,FUNCT_1:def 3,NAT_1:13; 0 <= (h2.j) & (h2.j) <= 1 by A29,A309,BORSUK_1:40,XXREAL_1:1; then LE h0/.i,h0/.(i+1),Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23 ,A24,A25,A304,A307,A301,A302,A288,A299,Th18; hence thesis by A46,A32,A303,A292,A305,A300,A297,A302,A288,A306,A310 ,A308,FUNCT_1:def 4,JORDAN6:def 10; end; suppose A311: i=len h1; then A312: i-len h11=i-'len h11 by A39,XREAL_1:233; i-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A262, XREAL_1:9; then A313: i-'len h11+2<=len h2-2+2 by A39,A312,XREAL_1:6; then A314: (i-'len h11 +2-'1)<=len h21 by A47,NAT_D:44; set j=i-'len h11+2-'1; A315: j+1 <> j; A316: 0+2<=i-'len h11 +2 by XREAL_1:6; then A317: j+1=i-'len h11+(1+1)-1+1 by Lm1,NAT_D:39,42 .=i-'len h11+2; 2-'1<=(i-'len h11 +2-'1) by A316,NAT_D:42; then 1 W-min P by A46,A34,A35,A32,A323,A331,A318,A330, FUNCT_1:def 4; hence thesis by A46,A32,A323,A331,A327,A328,A326,A318,A329,A330,A332 ,A325,A315,FUNCT_1:def 4,JORDAN6:def 10; end; end; end; then A333: LE h0/.1,h0/.(1+1),P & h0/.1<>h0/.(1+1) by A205; A334: E-max P in Upper_Arc P by A1,Th1; thus for i being Element of NAT,W being Subset of Euclid 2 st 1<=i & i W-min P by A38,A17,A71,A20,A340,A358,A353,A351, FUNCT_1:def 4; assume x in Segment(h0/.i,h0/.(i+1),P); then x in {p: LE h0/.i,p,P & LE p,h0/.(i+1),P} by A362,Def1; then consider p being Point of TOP-REAL 2 such that A363: p=x and A364: LE h0/.i,p,P and A365: LE p,h0/.(i+1),P; A366: h0/.i in Upper_Arc(P) & p in Lower_Arc(P)& not p=W-min(P) or h0 /.i in Upper_Arc(P) & p in Upper_Arc(P) & LE h0/.i,p,Upper_Arc(P),W-min(P), E-max(P) or h0/.i in Lower_Arc(P) & p in Lower_Arc(P)& not p=W-min(P) & LE h0/. i,p,Lower_Arc(P),E-max(P),W-min(P) by A364,JORDAN6:def 10; A367: p in Upper_Arc(P) & h0/.(i+1) in Lower_Arc(P) or p in Upper_Arc( P) & h0/.(i+1) in Upper_Arc(P) & LE p,h0/.(i+1),Upper_Arc(P),W-min(P),E-max(P) or p in Lower_Arc(P) & h0/.(i+1) in Lower_Arc(P)& LE p,h0/.(i+1),Lower_Arc(P), E-max(P),W-min(P) by A365,JORDAN6:def 10; now per cases by A352,XXREAL_0:1; suppose i+1 E-max P by A38,A45,A255,A20,A358,A353,A351, FUNCT_1:def 4; A369: now assume h0/.(i+1) in Lower_Arc(P); then h0/.(i+1) in Upper_Arc(P)/\ Lower_Arc(P) by A351,A360,XBOOLE_0:def 4; then h0/.(i+1) in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A362,A368,TARSKI:def 2; end; then A370: LE p,h0/.(i+1),Upper_Arc(P),W-min(P),E-max(P) by A365, JORDAN6:def 10; then A371: p<>E-max(P) by A3,A368,JORDAN6:55; A372: p in Upper_Arc(P) by A365,A369,JORDAN6:def 10; per cases by A335,XXREAL_0:1; suppose i>1; then A373: h0/.i <> W-min P by A38,A17,A71,A20,A342,A347,A348,A350, FUNCT_1:def 4; A374: h11.i <> E-max(P) by A38,A45,A255,A20,A341,A342,FUNCT_1:def 4; now assume h0/.i in Lower_Arc(P); then h0/.i in Upper_Arc(P)/\ Lower_Arc(P) by A350,A349, XBOOLE_0:def 4; then h0/.i in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A357,A350,A373,A374,TARSKI:def 2; end; then A375: h0/.i in Upper_Arc(P) & p in Lower_Arc(P) & not p=W-min(P) or h0/.i in Upper_Arc(P) & p in Upper_Arc(P) & LE h0/.i,p,Upper_Arc(P),W-min(P) ,E-max(P) by A364,JORDAN6:def 10; then A376: p <> W-min P by A3,A373,JORDAN6:54; A377: now assume p in Lower_Arc(P); then p in Upper_Arc(P)/\ Lower_Arc(P) by A372,XBOOLE_0:def 4; then p in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A371,A376,TARSKI:def 2; end; then consider z being set such that A378: z in dom g1 and A379: p=g1.z by A5,A375,FUNCT_1:def 3; reconsider rz=z as Real by A132,A378; A380: rz<=1 by A378,BORSUK_1:40,XXREAL_1:1; h1.(i+1) in rng h1 by A353,FUNCT_1:def 3; then A381: 0<=h1/.(i+1) & h1/.(i+1)<=1 by A11,A355,BORSUK_1:40,XXREAL_1:1; take z; thus z in dom g1 by A378; A382: g1.(h1/.i)=h0/.i & h1/.i<=1 by A335,A341,A357,A347,A344,A350, FINSEQ_4:15; g1.(h1/.(i+1))=h0/.(i+1) by A340,A352,A359,A351,FINSEQ_4:15; then A383: rz<=h1/.(i+1) by A4,A5,A6,A7,A370,A379,A381,A380,Th19; 0<=rz by A378,BORSUK_1:40,XXREAL_1:1; then h1/.i<=rz by A4,A5,A6,A7,A375,A377,A379,A382,A380,Th19; hence z in [.h1/.i,h1/.(i+1).] by A383,XXREAL_1:1; thus x = g1.z by A363,A379; end; suppose A384: i=1; now per cases; case A385: p<>W-min(P); now assume p in Lower_Arc(P); then p in Upper_Arc(P)/\ Lower_Arc(P) by A372, XBOOLE_0:def 4; then p in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A371,A385,TARSKI:def 2; end; then consider z being set such that A386: z in dom g1 and A387: p=g1.z by A5,A366,FUNCT_1:def 3; reconsider rz=z as Real by A132,A386; A388: h1/.1<=rz by A8,A346,A384,A386,BORSUK_1:40,XXREAL_1:1; h1.(1+1) in rng h1 by A353,A384,FUNCT_1:def 3; then A389: 0<=h1/.(1+1) & h1/.(1+1)<=1 by A11,A355,A384,BORSUK_1:40 ,XXREAL_1:1; A390: g1.(h1/.(1+1))=h0/.(1+1) by A352,A359,A351,A384,FINSEQ_4:15; take rz; rz<=1 by A386,BORSUK_1:40,XXREAL_1:1; then rz<=h1/.(1+1) by A4,A5,A6,A7,A370,A384,A387,A390,A389 ,Th19; hence rz in dom g1 & rz in [.h1/.1,h1/.(1+1).] & x = g1.rz by A363 ,A386,A387,A388,XXREAL_1:1; end; case A391: p=W-min(P); thus 0 in [.h1/.1,h1/.(1+1).] by A8,A354,A346,A355,A384, XXREAL_1:1; thus x = g1.0 by A6,A363,A391; end; end; hence ex y being set st y in dom g1 & y in [.h1/.i,h1/.(i+1).] & x = g1.y by A44,A384; end; end; suppose A392: i+1=len h1; then A393: h0/.(i+1)=E-max(P) by A7,A9,A45,A358,A351,FUNCT_1:13; A394: now assume that A395: p in Lower_Arc(P) and A396: not p in Upper_Arc(P); LE h0/.(i+1),p,Lower_Arc(P),E-max(P),W-min(P) by A21,A393,A395, JORDAN5C:10; hence contradiction by A334,A21,A367,A393,A396,JORDAN5C:12; end; p in Upper_Arc(P) or p in Lower_Arc(P) by A364,JORDAN6:def 10; then A397: LE p,h0/.(i+1),Upper_Arc(P),W-min(P),E-max(P) by A3,A393,A394, JORDAN5C:10; per cases; suppose A398: p<>E-max(P); now per cases; case A399: p<>W-min(P); A400: now assume p in Lower_Arc(P); then p in Upper_Arc(P)/\ Lower_Arc(P) by A394, XBOOLE_0:def 4; then p in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A398,A399,TARSKI:def 2; end; then consider z being set such that A401: z in dom g1 and A402: p=g1.z by A5,A366,FUNCT_1:def 3; reconsider rz=z as Real by A132,A401; A403: rz<=1 by A401,BORSUK_1:40,XXREAL_1:1; h1.(i+1) in rng h1 by A353,FUNCT_1:def 3; then A404: 0<=h1/.(i+1) & h1/.(i+1)<=1 by A11,A355,BORSUK_1:40 ,XXREAL_1:1; g1.(h1/.(i+1))=h0/.(i+1) by A340,A352,A359,A351,FINSEQ_4:15; then A405: rz<=h1/.(i+1) by A4,A5,A6,A7,A397,A402,A404,A403,Th19; take rz; 0<=rz by A401,BORSUK_1:40,XXREAL_1:1; then h1/.i<=rz by A4,A5,A6,A7,A357,A347,A344,A350,A346,A366 ,A400,A402,A403,Th19; hence rz in dom g1 & rz in [.h1/.i,h1/.(i+1).] & x = g1.rz by A363 ,A401,A402,A405,XXREAL_1:1; end; case A406: p=W-min(P); then h11.i=W-min(P) by A3,A357,A350,A366,JORDAN6:54; then i=1 by A38,A17,A71,A20,A342,FUNCT_1:def 4; then 0 in [.h1/.i,h1/.(i+1).] by A8,A354,A346,A355,XXREAL_1:1 ; hence ex y being set st y in dom g1 & y in [.h1/.i,h1/.(i+1) .] & x = g1.y by A6,A44,A363,A406; end; end; hence ex y being set st y in dom g1 & y in [.h1/.i,h1/.(i+1).] & x = g1.y; end; suppose A407: p=E-max(P); 1 in [.h1/.i,h1/.(i+1).] by A9,A354,A346,A355,A392,XXREAL_1:1; hence ex y being set st y in dom g1 & y in [.h1/.i,h1/.(i+1).] & x = g1.y by A7,A69,A363,A407,Lm6; end; end; end; hence thesis by FUNCT_1:def 6; end; A408: h1.(i+1)<=1 by A11,A356,BORSUK_1:40,XXREAL_1:1; g1.:([.h1/.i,h1/.(i+1).]) c= Segment(h0/.i,h0/.(i+1),P) proof A409: g1.(h1/.i)=h0/.i & 0<=h1/.i by A335,A341,A348,A345,A350,FINSEQ_4:15; let x be set; assume x in g1.:([.h1/.i,h1/.(i+1).]); then consider y being set such that A410: y in dom g1 and A411: y in [.h1/.i,h1/.(i+1).] and A412: x=g1.y by FUNCT_1:def 6; reconsider sy=y as Real by A411; A413: sy<=1 by A410,BORSUK_1:40,XXREAL_1:1; A414: x in Upper_Arc(P) by A5,A410,A412,FUNCT_1:def 3; then reconsider p1=x as Point of TOP-REAL 2; A415: h1/.i<=1 by A335,A341,A344,FINSEQ_4:15; h1/.i<=sy by A411,XXREAL_1:1; then LE h0/.i,p1,Upper_Arc(P),W-min(P),E-max(P) by A3,A4,A5,A6,A7,A412 ,A409,A415,A413,Th18; then A416: LE h0/.i,p1,P by A350,A349,A414,JORDAN6:def 10; sy<=h1/.(i+1) & 0<=sy by A410,A411,BORSUK_1:40,XXREAL_1:1; then LE p1,h0/.(i+1),Upper_Arc(P),W-min(P),E-max(P) by A3,A4,A5,A6,A7 ,A359,A408,A351,A355,A412,A413,Th18; then LE p1,h0/.(i+1),P by A351,A360,A414,JORDAN6:def 10; then A417: x in {p: LE h0/.i,p,P & LE p,h0/.(i+1),P} by A416; not h0/.(i+1)=W-min P by A38,A17,A71,A20,A340,A358,A353,A351, FUNCT_1:def 4; hence thesis by A417,Def1; end; then W=g1.:Q1 by A337,A361,XBOOLE_0:def 10; hence thesis by A13,A335,A341; end; suppose A418: i>len h1; i-len h11len h11 by A39,A418,NAT_1:13; then A424: i+1-len h11=i+1-'len h11 by XREAL_1:233; i+1 in dom h0 by A338,A340,FINSEQ_3:25; then A425: h0/.(i+1)=h0.(i+1) by PARTFUN1:def 6; A426: i<=len h11 + len (mid(h21,2,len h21 -'1)) by A336,FINSEQ_1:22; len h11+1<=i by A39,A418,NAT_1:13; then A427: h0.i=(mid(h21,2,len h21 -'1)).(i -len h11) by A426,FINSEQ_1:23; A428: i+1-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A338, XREAL_1:9; i in dom h0 by A335,A336,FINSEQ_3:25; then A429: h0/.i=h0.i by PARTFUN1:def 6; set j=i-'len h11+2-'1; len h2 W-min(P) by A46,A34,A35,A32,A440,A439,A429,FUNCT_1:def 4; A458: h2/.j<=1 by A29,A442,A445,BORSUK_1:40,XXREAL_1:1; let x be set; assume A459: x in Segment(h0/.i,h0/.(i+1),P); h0/.(i+1) <> W-min P by A46,A34,A35,A32,A422,A451,A419,A432,A450,A435 ,A425,FUNCT_1:def 4; then x in {p: LE h0/.i,p,P & LE p,h0/.(i+1),P} by A459,Def1; then consider p being Point of TOP-REAL 2 such that A460: p=x and A461: LE h0/.i,p,P and A462: LE p,h0/.(i+1),P; A463: h0/.i in Upper_Arc(P) & p in Lower_Arc(P)& not p=W-min(P) or h0 /.i in Upper_Arc(P) & p in Upper_Arc(P) & LE h0/.i,p,Upper_Arc(P),W-min(P), E-max(P) or h0/.i in Lower_Arc(P) & p in Lower_Arc(P)& not p=W-min(P) & LE h0/. i,p,Lower_Arc(P),E-max(P),W-min(P) by A461,JORDAN6:def 10; A464: h21.j <> E-max P by A46,A76,A77,A32,A453,A439,FUNCT_1:def 4; A465: now assume h0/.i in Upper_Arc(P); then h0/.i in Upper_Arc(P)/\ Lower_Arc(P) by A429,A443,XBOOLE_0:def 4 ; then h0/.i in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A440,A429,A457,A464,TARSKI:def 2; end; then A466: LE h0/.i,p,Lower_Arc P, E-max P, W-min P by A461,JORDAN6:def 10; A467: h0/.i <> E-max(P) by A46,A76,A77,A32,A440,A453,A439,A429,FUNCT_1:def 4; A468: now assume p in Upper_Arc(P); then p in Upper_Arc P /\ Lower_Arc P by A463,A465,XBOOLE_0:def 4; then p in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; then p=W-min(P) or p=E-max(P) by TARSKI:def 2; hence contradiction by A21,A463,A465,A467,JORDAN6:54; end; A469: h0/.(i+1) <> E-max P & h21.(j+1) <> W-min P by A46,A76,A34,A77,A35,A32 ,A422,A451,A419,A432,A450,A434,A435,A425,FUNCT_1:def 4; now assume h0/.(i+1) in Upper_Arc(P); then h0/.(i+1) in Upper_Arc(P)/\ Lower_Arc(P) by A425,A452, XBOOLE_0:def 4; then h0/.(i+1) in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; hence contradiction by A451,A450,A425,A469,TARSKI:def 2; end; then p in Lower_Arc(P) & h0/.(i+1) in Lower_Arc(P)& not h0/.(i+ 1)= W-min(P) & LE p,h0/.(i+1),Lower_Arc(P),E-max(P),W-min(P) or p in Upper_Arc(P) & h0/.(i+1) in Lower_Arc(P) & not h0/.(i+1)=W-min(P) by A462,JORDAN6:def 10; then consider z being set such that A470: z in dom g2 and A471: p=g2.z by A23,A468,FUNCT_1:def 3; reconsider rz=z as Real by A131,A470; A472: rz<=1 by A470,BORSUK_1:40,XXREAL_1:1; LE p,h0/.(i+1),Lower_Arc(P),E-max(P),W-min(P) by A462,A468, JORDAN6:def 10; then A473: rz<=h2/.(j+1) by A22,A23,A24,A25,A471,A456,A472,A455,Th19; 0<=rz by A470,BORSUK_1:40,XXREAL_1:1; then h2/.j<=rz by A22,A23,A24,A25,A441,A429,A445,A466,A471,A458,A472 ,Th19; then rz in [.h2/.j,h2/.(j+1).] by A473,XXREAL_1:1; hence thesis by A460,A470,A471,FUNCT_1:def 6; end; A474: g2.(h2.(j+1)) = h0/.(i+1) by A451,A450,A435,A425,FUNCT_1:13; g2.:([.h2/.j,h2/.(j+1).]) c= Segment(h0/.i,h0/.(i+1),P) proof let x be set; assume x in g2.:([.h2/.j,h2/.(j+1).]); then consider y being set such that A475: y in dom g2 and A476: y in [.h2/.j,h2/.(j+1).] and A477: x=g2.y by FUNCT_1:def 6; reconsider sy=y as Real by A476; A478: sy<=h2/.(j+1) by A476,XXREAL_1:1; A479: x in Lower_Arc(P) by A23,A475,A477,FUNCT_1:def 3; then reconsider p1=x as Point of TOP-REAL 2; A480: h2.(j+1) <> 1 by A27,A30,A34,A422,A419,A432,A435,FUNCT_1:def 4; A481: now assume p1=W-min(P); then 1=sy by A22,A25,A227,A475,A477,FUNCT_1:def 4; hence contradiction by A437,A438,A478,A480,XXREAL_0:1; end; A482: sy<=1 by A475,BORSUK_1:40,XXREAL_1:1; h2/.j<=sy by A476,XXREAL_1:1; then LE h0/.i,p1,Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23,A24,A25 ,A441,A429,A446,A445,A477,A482,Th18; then A483: LE h0/.i,p1,P by A429,A443,A479,A481,JORDAN6:def 10; A484: h0/.(i+1) <> W-min P by A46,A34,A35,A32,A422,A451,A419,A432,A450,A435 ,A425,FUNCT_1:def 4; 0<=sy by A475,BORSUK_1:40,XXREAL_1:1; then LE p1,h0/.(i+1),Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23,A24 ,A25,A474,A437,A438,A477,A478,A482,Th18; then LE p1,h0/.(i+1),P by A425,A452,A479,A484,JORDAN6:def 10; then x in {p: LE h0/.i,p,P & LE p,h0/.(i+1),P} by A483; hence thesis by A484,Def1; end; then W=g2.:(Q1) by A337,A454,XBOOLE_0:def 10; hence thesis by A31,A433,A444; end; suppose A485: i=len h1; A486: i+1-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A338, XREAL_1:9; then 1<=i+1-'len h11 by A39,A339,A485,XREAL_1:233; then 1W-min(P) by A46,A34,A35,A32,A507,A517,A494,A488,FUNCT_1:def 4; A520: g2.(h2/.(j+1))=h0/.(i+1) by A496,A491,A503,A515,A501,FINSEQ_4:15; h2.(j+1) in rng h2 by A504,FUNCT_1:def 3; then A521: 0<=h2/.(j+1) & h2/.(j+1)<=1 by A29,A510,BORSUK_1:40,XXREAL_1:1; A522: h0/.(i+1) in Lower_Arc(P) by A23,A131,A29,A515,A505,A501,BORSUK_1:40 ,FUNCT_1:def 3; let x be set; assume A523: x in Segment(h0/.i,h0/.(i+1),P); h0/.(i+1) <> W-min P by A46,A34,A35,A32,A498,A514,A504,A501, FUNCT_1:def 4; then x in {p: LE h0/.i,p,P & LE p,h0/.(i+1),P} by A523,Def1; then consider p being Point of TOP-REAL 2 such that A524: p=x and A525: LE h0/.i,p,P and A526: LE p,h0/.(i+1),P; A527: h0/.i in Upper_Arc(P) & p in Lower_Arc(P)& not p=W-min(P) or h0 /.i in Upper_Arc(P) & p in Upper_Arc(P) & LE h0/.i,p,Upper_Arc(P),W-min(P), E-max(P) or h0/.i in Lower_Arc(P) & p in Lower_Arc(P)& not p=W-min(P) & LE h0/. i,p,Lower_Arc(P),E-max(P),W-min(P) by A525,JORDAN6:def 10; dom (g1*h1) c= dom h0 by FINSEQ_1:26; then A528: h0/.i=E-max(P) by A254,A485,A489,PARTFUN1:def 6; A529: now assume A530: not p in Lower_Arc(P); then p=E-max(P) by A3,A527,A528,JORDAN6:55; hence contradiction by A1,A530,Th1; end; A531: now assume p in Upper_Arc(P); then p in Upper_Arc(P)/\ Lower_Arc(P) by A529,XBOOLE_0:def 4; then A532: p in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; p <> W-min P by A3,A527,A519,JORDAN6:54; hence p = E-max P by A532,TARSKI:def 2; end; then p in rng g2 by A1,A23,A525,Th1,JORDAN6:def 10; then consider z being set such that A533: z in dom g2 and A534: p=g2.z by FUNCT_1:def 3; reconsider rz=z as Real by A131,A533; 0<=rz by A533,BORSUK_1:40,XXREAL_1:1; then A535: h2/.j<=rz by A26,A485,A511,A492,Lm1,FINSEQ_4:15; A536: not h0/.(i+1)=E-max(P) by A46,A76,A77,A32,A503,A514,A504,A501, FUNCT_1:def 4; now assume h0/.(i+1) in Upper_Arc(P); then h0/.(i+1) in Upper_Arc(P)/\ Lower_Arc(P) by A522,XBOOLE_0:def 4; then h0/.(i+1) in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; then h21.(j+1)=W-min(P) by A514,A501,A536,TARSKI:def 2; hence contradiction by A46,A34,A35,A32,A498,A504,FUNCT_1:def 4; end; then p in Lower_Arc(P) & h0/.(i+1) in Lower_Arc(P) & not h0/.(i +1)= W-min(P) & LE p,h0/.(i+1),Lower_Arc(P),E-max(P),W-min(P) or p in Upper_Arc(P) & h0/.(i+1) in Lower_Arc(P) & not h0/.(i+1)=W-min(P) by A526,JORDAN6:def 10; then A537: LE p,h0/.(i+1),Lower_Arc P, E-max P, W-min P by A21,A531,JORDAN5C:10; rz<=1 by A533,BORSUK_1:40,XXREAL_1:1; then rz<=h2/.(j+1) by A22,A23,A24,A25,A537,A534,A520,A521,Th19; then rz in [.h2/.j,h2/.(j+1).] by A535,XXREAL_1:1; hence thesis by A524,A533,A534,FUNCT_1:def 6; end; A538: g2.(h2.(j+1)) = h0/.(i+1) by A514,A504,A501,FUNCT_1:13; g2.:([.h2/.j,h2/.(j+1).]) c= Segment(h0/.i,h0/.(i+1),P) proof let x be set; assume x in g2.:([.h2/.j,h2/.(j+1).]); then consider y being set such that A539: y in dom g2 and A540: y in [.h2/.j,h2/.(j+1).] and A541: x=g2.y by FUNCT_1:def 6; reconsider sy=y as Real by A540; A542: sy<=h2/.(j+1) by A540,XXREAL_1:1; A543: x in Lower_Arc(P) by A23,A539,A541,FUNCT_1:def 3; then reconsider p1=x as Point of TOP-REAL 2; A544: h2.(j+1) <> 1 by A27,A30,A34,A498,A504,FUNCT_1:def 4; A545: now assume p1=W-min(P); then 1=sy by A22,A25,A227,A539,A541,FUNCT_1:def 4; hence contradiction by A506,A510,A542,A544,XXREAL_0:1; end; A546: 0<=sy & sy<=1 by A539,BORSUK_1:40,XXREAL_1:1; then LE h0/.i,p1,Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23,A24,A25 ,A489,A488,A541,Th18; then A547: LE h0/.i,p1,P by A488,A509,A543,A545,JORDAN6:def 10; A548: h0/.(i+1) <> W-min(P) by A46,A34,A35,A32,A498,A514,A504,A501, FUNCT_1:def 4; LE p1,h0/.(i+1),Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23,A24,A25 ,A538,A506,A510,A541,A542,A546,Th18; then LE p1,h0/.(i+1),P by A501,A516,A543,A548,JORDAN6:def 10; then x in {p: LE h0/.i,p,P & LE p,h0/.(i+1),P} by A547; hence thesis by A548,Def1; end; then W=g2.:(Q1) by A337,A518,XBOOLE_0:def 10; hence thesis by A31,A502,A512; end; end; A549: len h0=len h1+(len h2-2) by A38,A47,A36,A52,A55,A57,FINSEQ_3:29; thus for W being Subset of Euclid 2 st W=Segment(h0/.len h0,h0/.1,P) holds diameter W < e proof set i=len h0; let W be Subset of Euclid 2; set j=i-'len h11+2-'1; A550: 0+2<=i-'len h11 +2 by XREAL_1:6; then A551: 1<=(i-'len h11 +2-'1) by Lm1,NAT_D:42; len h11+1-len h11<=i-len h11 by A47,A36,A52,A55,A57,A62,XXREAL_0:2; then 1<=i-'len h11 by NAT_D:39; then 1+2<=i-'len h11+2 by XREAL_1:6; then A552: 1+2-1<=i-'len h11+2-1 by XREAL_1:9; len h0<=len h11 + len mid(h21,2,len h21 -'1) by FINSEQ_1:22; then A553: h0.i=(mid(h21,2,len h21 -'1)).(i -len h11) by A39,A64,FINSEQ_1:23; A554: i-len h11=i-'len h11 by A39,A65,XREAL_1:233; then (i-'len h11 +2-'1)<=len h21 by A36,A52,A55,A57,NAT_D:44; then A555: j in dom h2 by A46,A551,FINSEQ_3:25; then A556: h2.j in rng h2 by FUNCT_1:def 3; i-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 & len h1 + 1-len h1 <=i-len h1 by A549,A62,FINSEQ_1:22,XXREAL_0:2; then A557: h0.i=h21.(i-'len h11 +2-'1) by A39,A48,A56,A50,A54,A553,A554,FINSEQ_6:118 ; then A558: h0.i=g2.(h2.j) by A555,FUNCT_1:13; then A559: h0.i in Lower_Arc P by A23,A131,A29,A556,BORSUK_1:40,FUNCT_1:def 3; A560: 2-'1<=(i-'len h11 +2-'1) by A550,NAT_D:42; then A561: 1W-min(P) or not h0/.i in P); then p in Lower_Arc(P) by A567,A565,JORDAN6:def 10; then consider z being set such that A578: z in dom g2 and A579: p=g2.z by A23,FUNCT_1:def 3; take z; thus z in dom g2 by A578; reconsider rz=z as Real by A131,A578; A580: rz<=1 by A578,BORSUK_1:40,XXREAL_1:1; then A581: rz<=h2/.(j+1) by A27,A47,A36,A52,A55,A57,A554,A561,FINSEQ_4:15; A582: LE h0/.i,p,Lower_Arc(P),E-max(P),W-min(P) by A567,A565,A577, JORDAN6:def 10; 0<=rz by A578,BORSUK_1:40,XXREAL_1:1; then h2/.j<=rz by A22,A23,A24,A25,A558,A568,A565,A564,A582,A579,A580 ,Th19; hence z in [.h2/.j,h2/.(j+1).] & x = g2.z by A574,A579,A581, XXREAL_1:1; end; suppose h0/.i in P & p=W-min(P); hence ex y being set st y in dom g2 & y in [.h2/.j,h2/.(j+1).] & x = g2.y by A25,A227,A574,A573,A576; end; end; hence thesis by FUNCT_1:def 6; end; A583: 0 <= h2.j & h2.j <= 1 by A29,A556,BORSUK_1:40,XXREAL_1:1; A584: g2.:([.h2/.j,h2/.(j+1).]) c= Segment(h0/.i,h0/.1,P) proof A585: Upper_Arc(P) \/ Lower_Arc(P)=P by A1,JORDAN6:def 9; let x be set; assume x in g2.:([.h2/.j,h2/.(j+1).]); then consider y being set such that A586: y in dom g2 and A587: y in [.h2/.j,h2/.(j+1).] and A588: x=g2.y by FUNCT_1:def 6; reconsider sy=y as Real by A587; A589: x in Lower_Arc(P) by A23,A586,A588,FUNCT_1:def 3; then reconsider p1=x as Point of TOP-REAL 2; h2/.j<=sy & sy<=1 by A586,A587,BORSUK_1:40,XXREAL_1:1; then A590: LE h0/.i,p1,Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23,A24,A25,A558 ,A565,A583,A564,A588,Th18; now per cases; case p1=W-min(P); hence LE h0/.i,p1,P or h0/.i in P & p1=W-min(P) by A559,A565,A585, XBOOLE_0:def 3; end; case p1<>W-min(P); hence LE h0/.i,p1,P or h0/.i in P & p1=W-min(P) by A559,A565,A589 ,A590,JORDAN6:def 10; end; end; then A591: x in {p: LE h0/.i,p,P or h0/.i in P & p=W-min(P)}; h0/.1=W-min(P) by A72,A67,PARTFUN1:def 6; hence thesis by A591,Def1; end; assume W=Segment(h0/.len h0,h0/.1,P); then W=g2.:Q1 by A569,A584,XBOOLE_0:def 10; hence thesis by A31,A47,A36,A52,A55,A57,A554,A560,A563,Lm1; end; A592: for i being Element of NAT st 1<=i & i+1=len h1; per cases by A615,XXREAL_0:1; suppose A616: i+1>len h1; set j=(i+1)-'len h11+2-'1; A617: (i+1)+1-len h11 <=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36,A595,XREAL_1:9; A618: 0+2<=(i+1)-'len h11 +2 by XREAL_1:6; then A619: 1<=((i+1)-'len h11 +2-'1) by Lm1,NAT_D:42; A620: j+1=(i+1)-'len h11+(1+1)-1+1 by A618,Lm1,NAT_D:39,42 .=(i+1)-'len h11+2; A621: len h1 +1<=i+1 by A616,NAT_1:13; then A622: len h1 +1-len h1<=(i+1)-len h1 by XREAL_1:9; A623: (i+1)-len h11=(i+1)-'len h11 by A39,A616,XREAL_1:233; (i+1)+1>len h11 by A39,A616,NAT_1:13; then A624: (i+1)+1-len h11=(i+1)+1-'len h11 by XREAL_1:233; A625: len h1 +1<=(i+1)+1 by A621,NAT_1:13; then A626: len h1 +1-len h1<=(i+1)+1-len h1 by XREAL_1:9; then 1<(i+1)+1-'len h11+(2-1) by A39,A624,NAT_1:13; then A627: 0<(i+1)+1-'len h11+2-1; (i+1)-'len h11+2-'1=(i+1)-'len h11+2-1 by A618,Lm1,NAT_D:39,42; then A628: j+1=(i+1)+1-'len h11+2-'1 by A623,A624,A627,XREAL_0:def 2; (i+1)-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57 ,A594,XREAL_1:9; then A629: (i+1)-'len h11+2<=len h2-2+2 by A39,A623,XREAL_1:6; then ((i+1)-'len h11 +2-'1)<=len h21 by A47,NAT_D:44; then A630: j in dom h2 by A46,A619,FINSEQ_3:25; 2-'1<=((i+1)-'len h11 +2-'1) by A618,NAT_D:42; then 1 W-min P by A46,A34,A35,A32,A623,A641,A620,A628,A631,A640 ,FUNCT_1:def 4; i+1 in dom h0 by A594,A597,FINSEQ_3:25; then A645: h0/.(i+1)=h0.(i+1) by PARTFUN1:def 6; 0<=h2.j & h2.j<=1 by A29,A638,BORSUK_1:40,XXREAL_1:1; then LE h0/.(i+1),h0/.((i+1)+1),Lower_Arc(P),E-max(P),W-min(P) by A21 ,A22,A23,A24,A25,A637,A642,A634,A645,A640,A633,Th18; hence thesis by A645,A640,A639,A643,A644,JORDAN6:def 10; end; suppose A646: i+1=len h1; then len h1+1 <=len h11 + len (mid(h21,2,len h21 -'1)) by A595, FINSEQ_1:22; then A647: (i+1)+1-len h11 <=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A646,XREAL_1:9; then 1<=(i+1)+1-'len h11 by A39,A596,A646,XREAL_1:233; then 1<(i+1)+1-'len h11+(2-1) by NAT_1:13; then A648: 0<(i+1)+1-'len h11+2-1; A649: (i+1)+1-len h11=(i+1)+1-'len h11 by A39,A596,A646,XREAL_1:233; len h1 in dom h0 by A594,A597,A646,FINSEQ_3:25; then A650: h0/.len h1=h0.len h1 by PARTFUN1:def 6; set j=(i+1)-'len h11+2-'1; A651: 0+2<=(i+1)-'len h11 +2 by XREAL_1:6; then A652: j+1=(i+1)-'len h11+(1+1)-1+1 by Lm1,NAT_D:39,42 .=(i+1)-'len h11+(1+1); 2-'1<=((i+1)-'len h11 +2-'1) by A651,NAT_D:42; then A653: 1 W-min P by A46,A34,A35,A32,A658,A659,A654,A657, FUNCT_1:def 4; hence thesis by A646,A650,A657,A660,A656,JORDAN6:def 10; end; end; end; thus for i being Element of NAT st 1<=i & i+1W-min(P) by A256; h0/.i<>h0/.(i+1) & LE h0/.(i+1),h0/.(i+2),P by A592,A256,A661; hence thesis by A1,A662,Th10; end; A663: 2 in dom h0 by A201,FINSEQ_3:25; i <> 1 by A59,Lm2; then A664: h0/.i <> h0/.1 by A67,A78,A203,PARTFUN2:10; A665: len h1 in dom h1 by A16,FINSEQ_3:25; thus Segment(h0/.len h0,h0/.1,P)/\ Segment(h0/.1,h0/.2,P)={h0/.1} proof defpred P[Element of NAT] means $1+2<=len h0 implies LE h0/.2,h0/.($1+2),P; set j=len h0-'len h11+2-'1; A666: len h0 -len h11 <=len h11 + len mid(h21,2,len h21 -'1) -len h11 by FINSEQ_1:22; A667: h0/.2=h0.2 by A663,PARTFUN1:def 6; A668: for k being Element of NAT st P[k] holds P[k+1] proof let k be Element of NAT; assume A669: k+2<=len h0 implies LE h0/.2,h0/.(k+2),P; now A670: k+1+1=k+2; A671: k+1+2=k+2+1; assume A672: k+1+2<=len h0; then k+2 W-min(P) by A38,A17,A71,A15,A20,FUNCT_1:def 4; len h1 +1-len h1<=len h0 -len h1 & h0.len h0=(mid(h21,2,len h21 -'1) ).(len h0 -len h11) by A39,A36,A549,A62,A64,FINSEQ_1:23,XXREAL_0:2; then h0.len h0=h21.(len h0-'len h11 +2-'1) by A39,A48,A56,A50,A54,A252,A666 ,FINSEQ_6:118; then A680: h0.len h0=g2.(h2.j) by A675,FUNCT_1:13; A681: now h2.j in rng h2 by A675,FUNCT_1:def 3; then A682: g2.(h2.j) in rng g2 by A131,A29,BORSUK_1:40,FUNCT_1:def 3; assume h0/.2=h0/.len h0; then h0/.2 in Upper_Arc(P)/\ Lower_Arc(P) by A23,A75,A676,A680,A682, XBOOLE_0:def 4; then h0/.2 in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; then h11.2=E-max(P) by A40,A679,A667,TARSKI:def 2; hence contradiction by A38,A665,A255,A14,A15,A20,FUNCT_1:def 4; end; h0/.2<>W-min(P) by A663,A40,A679,PARTFUN1:def 6; hence thesis by A1,A73,A681,A678,A673,Th12; end; A683: i+1 = len h0 by A16,A65,XREAL_1:235,XXREAL_0:2; then LE h0/.i,h0/.(i+1),P & h0/.(i+1)<>W-min(P) by A256,A202; hence Segment(h0/.i,h0/.len h0,P)/\ Segment(h0/.len h0,h0/.1,P)={h0/.len h0} by A1,A73,A683,A664,Th11; LE h0/.i,h0/.(i+1),P by A256,A202,A200; hence Segment(h0/.i,h0/.len h0,P) misses Segment(h0/.1,h0/.2,P) by A1,A683 ,A333,A229,A207,Th13; thus for i,j being Element of NAT st 1<=i & i < j & j < len h0 & not i,j are_adjacent1 holds Segment(h0/.i,h0/.(i+1),P) misses Segment(h0/.j,h0/.(j+1),P ) proof let i,j be Element of NAT; assume that A684: 1<=i and A685: i < j and A686: j < len h0 and A687: not i,j are_adjacent1; A688: 1h0/.(i+1) by A256,A684; A691: i+1<=j by A685,NAT_1:13; then A692: (i+1)len h1; j in dom h0 by A686,A688,FINSEQ_3:25; then A707: h0/.j=h0.j by PARTFUN1:def 6; A708: j-len h11=j-'len h11 by A39,A706,XREAL_1:233; j-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A686, XREAL_1:9; then j-'len h11+2<=len h2-2+2 by A39,A708,XREAL_1:6; then A709: (j-'len h11 +2-'1)<= len h21 by A47,NAT_D:44; j-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A686, XREAL_1:9; then A710: j-'len h11+2<=len h2-2+2 by A39,A708,XREAL_1:6; set k=j-'len h11+2-'1; j<= len h11 + len (mid(h21,2,len h21 -'1)) by A686,FINSEQ_1:22; then A711: j-len h11<=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by XREAL_1:9; A712: 0+2<=j-'len h11 +2 by XREAL_1:6; then A713: j-'len h11+2-'1=j-'len h11+2-1 by Lm1,NAT_D:39,42; 1<=(j-'len h11 +2-'1) by A712,Lm1,NAT_D:42; then A714: k in dom h2 by A46,A709,FINSEQ_3:25; then h2.k in rng h2 by FUNCT_1:def 3; then A715: g2.(h2.k) in rng g2 by A131,A29,BORSUK_1:40,FUNCT_1:def 3; A716: len h1 +1<=j by A706,NAT_1:13; then h0.j=(mid(h21,2,len h21 -'1)).(j -len h11) & len h1 +1-len h1 <=j-len h1 by A39,A36,A686,FINSEQ_1:23,XREAL_1:9; then A717: h0.j=h21.(j-'len h11 +2-'1) by A39,A48,A56,A50,A54,A708,A711, FINSEQ_6:118; then h0.j=g2.(h2.k) by A714,FUNCT_1:13; then h0.j in Upper_Arc(P) /\ Lower_Arc(P) by A23,A696,A701,A703,A707 ,A715,XBOOLE_0:def 4; then A718: h0.j in {W-min(P),E-max(P)} by A1,JORDAN6:def 9; len h11+1-len h11<=j-len h11 by A39,A716,XREAL_1:9; then 1<=j-'len h11 by NAT_D:39; then 1+2<=j-'len h11+2 by XREAL_1:6; then 1+2-1<=j-'len h11+2-1 by XREAL_1:9; then 1 E-max P by A46,A76,A77,A32,A717,A714,FUNCT_1:def 4; j-'len h11+2-'1 W-min P by A46,A34,A35,A32,A717,A713,A710,A714, FUNCT_1:def 4; hence contradiction by A718,A719,TARSKI:def 2; end; end; suppose A720: i+1>len h1; then A721: j>len h1 by A691,XXREAL_0:2; then A722: len h1 +1<=j by NAT_1:13; then A723: len h1 +1-len h1<=j-len h1 by XREAL_1:9; len h11+1-len h11<=j-len h11 by A39,A722,XREAL_1:9; then A724: j-'len h11=j-len h11 by NAT_D:39; A725: len h1 +1<=i+1 by A720,NAT_1:13; then len h11+1-len h11<=(i+1)-len h11 by A39,XREAL_1:9; then (i+1)-'len h11=(i+1)-len h11 by NAT_D:39; then i+1-'len h11len h1; set k=j-'len h11+2-'1; 0+2<=j-'len h11 +2 by XREAL_1:6; then A765: 2-'1<=j-'len h11 +2-'1 by NAT_D:42; A766: j-len h11=j-'len h11 by A39,A764,XREAL_1:233; j-len h11<=len h1+(len h2-2)-len h11 by A39,A47,A36,A52,A55,A57,A686, XREAL_1:9; then j-'len h11+2<=len h2-2+2 by A39,A766,XREAL_1:6; then (j-'len h11 +2-'1)<=len h21 by A47,NAT_D:44; then A767: (j-'len h11 +2-'1) in dom h21 by A765,Lm1,FINSEQ_3:25; j+1-1<=len h1+(len h2-2)-1 by A39,A47,A36,A52,A55,A57,A743,XREAL_1:9 ; then j-len h11<=len h1+((len h2-2)-1)-len h11 by XREAL_1:9; then j-'len h11+2<=len h2-2-1+2 by A39,A766,XREAL_1:6; then A768: j-'len h11+2-1<=len h2-1-1 by XREAL_1:9; A769: h0.(i+1)=h11.(i+1) by A39,A744,A748,FINSEQ_1:64; i+1 in dom h1 by A744,A748,FINSEQ_3:25; then h1.(i+1) in rng h1 by FUNCT_1:def 3; then A770: g1.(h1.(i+1)) in rng g1 by A132,A11,BORSUK_1:40,FUNCT_1:def 3; 0+1<=j-'len h11+1+1-1 by XREAL_1:6; then A771: j-'len h11+2-'1=j-'len h11+2-1 by NAT_D:39; len h1 +1<=j by A764,NAT_1:13; then A772: h0.j=(mid(h21,2,len h21 -'1)).(j -len h11) & len h1 +1-len h1 <=j-len h1 by A39,A36,A686,FINSEQ_1:23,XREAL_1:9; A773: j-len h11 <=len h11 + len (mid(h21,2,len h21 -'1))-len h11 by A36 ,A686,XREAL_1:9; then h0.j=h21.(j-'len h11 +2-'1) by A39,A48,A56,A50,A54,A766,A772, FINSEQ_6:118; then A774: h0.j=g2.(h2.k) by A46,A767,FUNCT_1:13; j-len h11=j-'len h11 by A39,A764,XREAL_1:233; then A775: h0.j=h21.k by A39,A48,A56,A50,A54,A773,A772,FINSEQ_6:118; j in dom h0 by A686,A688,FINSEQ_3:25; then A776: h0/.j=h0.j by PARTFUN1:def 6; h2.k in rng h2 by A46,A767,FUNCT_1:def 3; then A777: h0.j in Lower_Arc(P) by A23,A131,A29,A774,BORSUK_1:40,FUNCT_1:def 3; i+1 in Seg len h1 by A745,A748,FINSEQ_1:1; then i+1 in dom h1 by FINSEQ_1:def 3; then A778: h11.(i+1)=g1.(h1.(i+1)) by FUNCT_1:13; (i+1) in dom h0 by A745,A692,FINSEQ_3:25; then A779: h0/.(i+1)=h0.(i+1) by PARTFUN1:def 6; len h2-1-1 W-min P by A46,A34,A35,A32,A771,A767,A768,A775,A776, FUNCT_1:def 4; hence thesis by A5,A769,A778,A779,A776,A770,A777,JORDAN6:def 10; end; end; suppose A780: i+1>len h1; set j0=(i+1)-'len h11+2-'1; set k=j-'len h11+2-'1; A781: 0+2<=(i+1)-'len h11 +2 by XREAL_1:6; then A782: 1<=((i+1)-'len h11 +2-'1) by Lm1,NAT_D:42; A783: j-len h11=j-'len h11 by A39,A691,A780,XREAL_1:233,XXREAL_0:2; len h1 W-min P by A46,A34,A35,A32,A796,A798,A795,A788,A809, FUNCT_1:def 4; h21.k=g2.(h2.k) by A46,A798,FUNCT_1:13; then LE h0/.(i+1),h0/.j,Lower_Arc(P),E-max(P),W-min(P) by A21,A22,A23 ,A24,A25,A801,A800,A810,A792,A805,A806,A809,Th18; hence thesis by A23,A810,A806,A809,A793,A802,A811,JORDAN6:def 10; end; end; LE h0/.j,h0/.(j+1),P by A256,A688,A743; hence thesis by A1,A690,A747,A695,Th13; end; let i be Element of NAT such that A812: 1 < i and A813: i+1 < len h0; A814: 1 E-max P by A46,A76,A77,A32,A829,A827,FUNCT_1:def 4; len h0-'len h11+2-'1 W-min P by A46,A47,A34,A35,A36,A52,A55,A57,A252,A32 ,A829,A827,FUNCT_1:def 4; hence contradiction by A830,A831,TARSKI:def 2; end; suppose A832: i+1>len h1; set k=len h0-'len h11+2-'1; set j0=(i+1)-'len h11+2-'1; A833: 0+2<=len h0-'len h11 +2 by XREAL_1:6; then A834: 2-'1<=(len h0-'len h11 +2-'1) by NAT_D:42; len h0-'len h11 +2-'1 <= len h21 by A36,A52,A55,A57,A252,NAT_D:44; then A835: k in dom h2 by A46,A834,Lm1,FINSEQ_3:25; i+1 <= len h11 + len mid(h21,2,len h21 -'1) by A813,FINSEQ_1:22; then A836: i+1-len h11 <=len h11 + len mid(h21,2,len h21 -'1)-len h11 by XREAL_1:9; A837: len h1 +1<=i+1 by A832,NAT_1:13; then len h11+1-len h11<=(i+1)-len h11 by A39,XREAL_1:9; then A838: (i+1)-'len h11=(i+1)-len h11 by NAT_D:39; len h0-'len h11=len h0-len h11 by A36,A57,XREAL_0:def 2; then i+1-'len h11len h1; then len h1+1<=i+1 by NAT_1:13; then A856: len h1+1-len h1<=i+1-len h1 by XREAL_1:9; then A857: i+1-'len h11=i+1-len h11 by A39,NAT_D:39; A858: i+1-len h11W-min P by A72,A67,A78,A812,A878,FUNCT_1:def 4; LE h0/.i,h0/.(i+1),P by A256,A812,A813; hence thesis by A1,A72,A68,A879,A850,A817,Th14; end;