let C be Simple_closed_curve; :: thesis: for n, m being Nat st n is_sufficiently_large_for C & n <= m holds
L~ (Span (C,m)) c= Cl (LeftComp (Span (C,n)))

let i, j be Nat; :: thesis: ( i is_sufficiently_large_for C & i <= j implies L~ (Span (C,j)) c= Cl (LeftComp (Span (C,i))) )
assume that
A1: i is_sufficiently_large_for C and
A2: i <= j and
A3: not L~ (Span (C,j)) c= Cl (LeftComp (Span (C,i))) ; :: thesis: contradiction
A4: j is_sufficiently_large_for C by A1, A2, Th28;
then A5: Span (C,j) is_sequence_on Gauge (C,j) by JORDAN13:def 1;
set G = Gauge (C,j);
set f = Span (C,j);
consider p being Point of (TOP-REAL 2) such that
A6: p in L~ (Span (C,j)) and
A7: not p in Cl (LeftComp (Span (C,i))) by A3;
consider i1 being Nat such that
A8: 1 <= i1 and
A9: i1 + 1 <= len (Span (C,j)) and
A10: p in LSeg ((Span (C,j)),i1) by A6, SPPOL_2:13;
A11: i1 < len (Span (C,j)) by A9, NAT_1:13;
A12: Span (C,i) is_sequence_on Gauge (C,i) by A1, JORDAN13:def 1;
now :: thesis: left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= Cl (RightComp (Span (C,i)))
ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) )
proof
A13: 1 <= i1 + 1 by NAT_1:11;
then A14: i1 + 1 in dom (Span (C,j)) by A9, FINSEQ_3:25;
then consider i5, j5 being Nat such that
A15: [i5,j5] in Indices (Gauge (C,j)) and
A16: (Span (C,j)) /. (i1 + 1) = (Gauge (C,j)) * (i5,j5) by A5, GOBOARD1:def 9;
A17: 1 <= i5 by A15, MATRIX_0:32;
A18: j5 <= width (Gauge (C,j)) by A15, MATRIX_0:32;
A19: i5 <= len (Gauge (C,j)) by A15, MATRIX_0:32;
A20: 1 <= j5 by A15, MATRIX_0:32;
A21: i1 in dom (Span (C,j)) by A8, A11, FINSEQ_3:25;
then consider i4, j4 being Nat such that
A22: [i4,j4] in Indices (Gauge (C,j)) and
A23: (Span (C,j)) /. i1 = (Gauge (C,j)) * (i4,j4) by A5, GOBOARD1:def 9;
A24: 1 <= i4 by A22, MATRIX_0:32;
|.(i4 - i5).| + |.(j4 - j5).| = 1 by A5, A21, A22, A23, A14, A15, A16, GOBOARD1:def 9;
then A25: ( ( |.(i4 - i5).| = 1 & j4 = j5 ) or ( |.(j4 - j5).| = 1 & i4 = i5 ) ) by SEQM_3:42;
A26: 1 <= j4 by A22, MATRIX_0:32;
left_cell ((Span (C,j)),i1,(Gauge (C,j))) = left_cell ((Span (C,j)),i1,(Gauge (C,j))) ;
then A27: ( ( i4 = i5 & j4 + 1 = j5 & left_cell ((Span (C,j)),i1,(Gauge (C,j))) = cell ((Gauge (C,j)),(i4 -' 1),j4) ) or ( i4 + 1 = i5 & j4 = j5 & left_cell ((Span (C,j)),i1,(Gauge (C,j))) = cell ((Gauge (C,j)),i4,j4) ) or ( i4 = i5 + 1 & j4 = j5 & left_cell ((Span (C,j)),i1,(Gauge (C,j))) = cell ((Gauge (C,j)),i5,(j5 -' 1)) ) or ( i4 = i5 & j4 = j5 + 1 & left_cell ((Span (C,j)),i1,(Gauge (C,j))) = cell ((Gauge (C,j)),i4,j5) ) ) by A5, A8, A9, A22, A23, A15, A16, GOBRD13:def 3;
A28: j4 <= width (Gauge (C,j)) by A22, MATRIX_0:32;
A29: i4 <= len (Gauge (C,j)) by A22, MATRIX_0:32;
per cases ( ( i4 = i5 & j4 + 1 = j5 ) or ( i4 + 1 = i5 & j4 = j5 ) or ( i4 = i5 + 1 & j4 = j5 ) or ( i4 = i5 & j4 = j5 + 1 ) ) by A25, SEQM_3:41;
suppose A30: ( i4 = i5 & j4 + 1 = j5 ) ; :: thesis: ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) )

1 < i4 by A1, A2, A8, A11, A22, A23, Th22, Th28;
then 1 + 1 <= i4 by NAT_1:13;
then A31: 1 <= i4 -' 1 by JORDAN5B:2;
(i4 -' 1) + 1 = i4 by A24, XREAL_1:235;
hence ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) ) by A2, A29, A26, A18, A27, A30, A31, JORDAN1H:38; :: thesis: verum
end;
suppose A32: ( i4 + 1 = i5 & j4 = j5 ) ; :: thesis: ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) )

j4 < width (Gauge (C,j)) by A1, A2, A8, A11, A22, A23, Th25, Th28;
then j4 + 1 <= width (Gauge (C,j)) by NAT_1:13;
hence ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) ) by A2, A24, A26, A19, A27, A32, JORDAN1H:38; :: thesis: verum
end;
suppose A33: ( i4 = i5 + 1 & j4 = j5 ) ; :: thesis: ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) )

1 < j5 by A1, A2, A9, A13, A15, A16, Th24, Th28;
then 1 + 1 <= j5 by NAT_1:13;
then A34: 1 <= j5 -' 1 by JORDAN5B:2;
(j5 -' 1) + 1 = j5 by A20, XREAL_1:235;
hence ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) ) by A2, A29, A17, A18, A27, A33, A34, JORDAN1H:38; :: thesis: verum
end;
suppose A35: ( i4 = i5 & j4 = j5 + 1 ) ; :: thesis: ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) )

i4 < len (Gauge (C,j)) by A1, A2, A8, A11, A22, A23, Th23, Th28;
then i4 + 1 <= len (Gauge (C,j)) by NAT_1:13;
hence ex i2, j2 being Nat st
( 1 <= i2 & i2 + 1 <= len (Gauge (C,i)) & 1 <= j2 & j2 + 1 <= width (Gauge (C,i)) & left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) ) by A2, A24, A28, A20, A27, A35, JORDAN1H:38; :: thesis: verum
end;
end;
end;
then consider i2, j2 being Nat such that
1 <= i2 and
A36: i2 + 1 <= len (Gauge (C,i)) and
1 <= j2 and
A37: j2 + 1 <= width (Gauge (C,i)) and
A38: left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= cell ((Gauge (C,i)),i2,j2) ;
A39: j2 < width (Gauge (C,i)) by A37, NAT_1:13;
A40: LeftComp (Span (C,i)) is_a_component_of (L~ (Span (C,i))) ` by GOBOARD9:def 1;
A41: (Cl (RightComp (Span (C,i)))) \/ (LeftComp (Span (C,i))) = ((L~ (Span (C,i))) \/ (RightComp (Span (C,i)))) \/ (LeftComp (Span (C,i))) by GOBRD14:21
.= the carrier of (TOP-REAL 2) by GOBRD14:15 ;
assume not left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= Cl (RightComp (Span (C,i))) ; :: thesis: contradiction
then not cell ((Gauge (C,i)),i2,j2) c= Cl (RightComp (Span (C,i))) by A38;
then A42: cell ((Gauge (C,i)),i2,j2) meets LeftComp (Span (C,i)) by A41, XBOOLE_1:73;
A43: i2 < len (Gauge (C,i)) by A36, NAT_1:13;
then cell ((Gauge (C,i)),i2,j2) = Cl (Int (cell ((Gauge (C,i)),i2,j2))) by A39, GOBRD11:35;
then A44: Int (cell ((Gauge (C,i)),i2,j2)) meets LeftComp (Span (C,i)) by A42, TSEP_1:36;
A45: Int (left_cell ((Span (C,j)),i1,(Gauge (C,j)))) c= Int (cell ((Gauge (C,i)),i2,j2)) by A38, TOPS_1:19;
A46: Int (cell ((Gauge (C,i)),i2,j2)) is convex by A43, A39, GOBOARD9:17;
Int (cell ((Gauge (C,i)),i2,j2)) c= (L~ (Span (C,i))) ` by A12, A43, A39, Th33;
then Int (cell ((Gauge (C,i)),i2,j2)) c= LeftComp (Span (C,i)) by A44, A40, A46, GOBOARD9:4;
then Int (left_cell ((Span (C,j)),i1,(Gauge (C,j)))) c= LeftComp (Span (C,i)) by A45;
then Cl (Int (left_cell ((Span (C,j)),i1,(Gauge (C,j))))) c= Cl (LeftComp (Span (C,i))) by PRE_TOPC:19;
then A47: left_cell ((Span (C,j)),i1,(Gauge (C,j))) c= Cl (LeftComp (Span (C,i))) by A5, A8, A9, JORDAN9:11;
LSeg ((Span (C,j)),i1) c= left_cell ((Span (C,j)),i1,(Gauge (C,j))) by A5, A8, A9, JORDAN1H:20;
then LSeg ((Span (C,j)),i1) c= Cl (LeftComp (Span (C,i))) by A47;
hence contradiction by A7, A10; :: thesis: verum
end;
then A48: C meets Cl (RightComp (Span (C,i))) by A4, A8, A9, Th7, XBOOLE_1:63;
A49: Cl (RightComp (Span (C,i))) = (RightComp (Span (C,i))) \/ (L~ (Span (C,i))) by GOBRD14:21;
C misses L~ (Span (C,i)) by A1, Th8;
then A50: C meets RightComp (Span (C,i)) by A48, A49, XBOOLE_1:70;
C meets C ;
then A51: C meets LeftComp (Span (C,i)) by A1, Th11, XBOOLE_1:63;
reconsider D = (L~ (Span (C,i))) ` as Subset of (TOP-REAL 2) ;
D = (RightComp (Span (C,i))) \/ (LeftComp (Span (C,i))) by GOBRD12:10;
then A52: LeftComp (Span (C,i)) c= D by XBOOLE_1:7;
C c= LeftComp (Span (C,i)) by A1, Th11;
then A53: C c= D by A52;
A54: LeftComp (Span (C,i)) is_a_component_of D by GOBOARD9:def 1;
RightComp (Span (C,i)) is_a_component_of D by GOBOARD9:def 2;
hence contradiction by A50, A53, A54, A51, JORDAN9:1, SPRECT_4:6; :: thesis: verum