let C be Simple_closed_curve; :: thesis: for n, m being Element of 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 Element of 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, Th29;
then A5: Span C,j is_sequence_on Gauge C,j by JORDAN13:def 1;
A6: Span C,i is_sequence_on Gauge C,i by A1, JORDAN13:def 1;
consider p being Point of (TOP-REAL 2) such that
A7: p in L~ (Span C,j) and
A8: not p in Cl (LeftComp (Span C,i)) by A3, SUBSET_1:7;
reconsider D = (L~ (Span C,i)) ` as Subset of (TOP-REAL 2) ;
consider i1 being Element of NAT such that
A9: 1 <= i1 and
A10: i1 + 1 <= len (Span C,j) and
A11: p in LSeg (Span C,j),i1 by A7, SPPOL_2:13;
A12: i1 < len (Span C,j) by A10, NAT_1:13;
set f = Span C,j;
set G = Gauge C,j;
A13: now
assume A14: not left_cell (Span C,j),i1,(Gauge C,j) c= Cl (RightComp (Span C,i)) ; :: thesis: contradiction
ex i2, j2 being Element of 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
A15: i1 in dom (Span C,j) by A9, A12, FINSEQ_3:27;
then consider i4, j4 being Element of NAT such that
A16: [i4,j4] in Indices (Gauge C,j) and
A17: (Span C,j) /. i1 = (Gauge C,j) * i4,j4 by A5, GOBOARD1:def 11;
A18: ( 1 <= i4 & i4 <= len (Gauge C,j) ) by A16, MATRIX_1:39;
A19: ( 1 <= j4 & j4 <= width (Gauge C,j) ) by A16, MATRIX_1:39;
A20: 1 <= i1 + 1 by NAT_1:11;
then A21: i1 + 1 in dom (Span C,j) by A10, FINSEQ_3:27;
then consider i5, j5 being Element of NAT such that
A22: [i5,j5] in Indices (Gauge C,j) and
A23: (Span C,j) /. (i1 + 1) = (Gauge C,j) * i5,j5 by A5, GOBOARD1:def 11;
A24: ( 1 <= i5 & i5 <= len (Gauge C,j) ) by A22, MATRIX_1:39;
A25: ( 1 <= j5 & j5 <= width (Gauge C,j) ) by A22, MATRIX_1:39;
left_cell (Span C,j),i1,(Gauge C,j) = left_cell (Span C,j),i1,(Gauge C,j) ;
then A26: ( ( 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, A9, A10, A16, A17, A22, A23, GOBRD13:def 3;
(abs (i4 - i5)) + (abs (j4 - j5)) = 1 by A5, A15, A16, A17, A21, A22, A23, GOBOARD1:def 11;
then A27: ( ( abs (i4 - i5) = 1 & j4 = j5 ) or ( abs (j4 - j5) = 1 & i4 = i5 ) ) by GOBOARD1:2;
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 A27, GOBOARD1:1;
suppose A28: ( i4 = i5 & j4 + 1 = j5 ) ; :: thesis: ex i2, j2 being Element of 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 )

A29: (i4 -' 1) + 1 = i4 by A18, XREAL_1:237;
1 < i4 by A1, A2, A9, A12, A16, A17, Th23, Th29;
then 1 + 1 <= i4 by NAT_1:13;
then 1 <= i4 -' 1 by JORDAN5B:2;
hence ex i2, j2 being Element of 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, A18, A19, A25, A26, A28, A29, JORDAN1H:44; :: thesis: verum
end;
suppose A30: ( i4 + 1 = i5 & j4 = j5 ) ; :: thesis: ex i2, j2 being Element of 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, A9, A12, A16, A17, Th26, Th29;
then j4 + 1 <= width (Gauge C,j) by NAT_1:13;
hence ex i2, j2 being Element of 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, A18, A19, A24, A26, A30, JORDAN1H:44; :: thesis: verum
end;
suppose A31: ( i4 = i5 + 1 & j4 = j5 ) ; :: thesis: ex i2, j2 being Element of 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 )

A32: (j5 -' 1) + 1 = j5 by A25, XREAL_1:237;
1 < j5 by A1, A2, A10, A20, A22, A23, Th25, Th29;
then 1 + 1 <= j5 by NAT_1:13;
then 1 <= j5 -' 1 by JORDAN5B:2;
hence ex i2, j2 being Element of 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, A18, A24, A25, A26, A31, A32, JORDAN1H:44; :: thesis: verum
end;
suppose A33: ( i4 = i5 & j4 = j5 + 1 ) ; :: thesis: ex i2, j2 being Element of 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, A9, A12, A16, A17, Th24, Th29;
then i4 + 1 <= len (Gauge C,j) by NAT_1:13;
hence ex i2, j2 being Element of 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, A18, A19, A25, A26, A33, JORDAN1H:44; :: thesis: verum
end;
end;
end;
then consider i2, j2 being Element of NAT such that
A34: ( 1 <= i2 & i2 + 1 <= len (Gauge C,i) ) and
A35: ( 1 <= j2 & j2 + 1 <= width (Gauge C,i) ) and
A36: left_cell (Span C,j),i1,(Gauge C,j) c= cell (Gauge C,i),i2,j2 ;
A37: i2 < len (Gauge C,i) by A34, NAT_1:13;
A38: j2 < width (Gauge C,i) by A35, NAT_1:13;
A39: not cell (Gauge C,i),i2,j2 c= Cl (RightComp (Span C,i)) by A14, A36, XBOOLE_1:1;
(Cl (RightComp (Span C,i))) \/ (LeftComp (Span C,i)) = ((L~ (Span C,i)) \/ (RightComp (Span C,i))) \/ (LeftComp (Span C,i)) by GOBRD14:31
.= the carrier of (TOP-REAL 2) by GOBRD14:25 ;
then A40: cell (Gauge C,i),i2,j2 meets LeftComp (Span C,i) by A39, XBOOLE_1:73;
cell (Gauge C,i),i2,j2 = Cl (Int (cell (Gauge C,i),i2,j2)) by A37, A38, GOBRD11:35;
then A41: Int (cell (Gauge C,i),i2,j2) meets LeftComp (Span C,i) by A40, TSEP_1:40;
A42: Int (cell (Gauge C,i),i2,j2) c= (L~ (Span C,i)) ` by A6, A37, A38, Th34;
LeftComp (Span C,i) is_a_component_of (L~ (Span C,i)) ` by GOBOARD9:def 1;
then A43: Int (cell (Gauge C,i),i2,j2) c= LeftComp (Span C,i) by A37, A38, A41, A42, GOBOARD9:6, GOBOARD9:21;
Int (left_cell (Span C,j),i1,(Gauge C,j)) c= Int (cell (Gauge C,i),i2,j2) by A36, TOPS_1:48;
then Int (left_cell (Span C,j),i1,(Gauge C,j)) c= LeftComp (Span C,i) by A43, XBOOLE_1:1;
then Cl (Int (left_cell (Span C,j),i1,(Gauge C,j))) c= Cl (LeftComp (Span C,i)) by PRE_TOPC:49;
then A44: left_cell (Span C,j),i1,(Gauge C,j) c= Cl (LeftComp (Span C,i)) by A5, A9, A10, JORDAN9:13;
LSeg (Span C,j),i1 c= left_cell (Span C,j),i1,(Gauge C,j) by A5, A9, A10, JORDAN1H:26;
then LSeg (Span C,j),i1 c= Cl (LeftComp (Span C,i)) by A44, XBOOLE_1:1;
hence contradiction by A8, A11; :: thesis: verum
end;
A45: C c= LeftComp (Span C,i) by A1, Th12;
left_cell (Span C,j),i1,(Gauge C,j) meets C by A4, A9, A10, Th8;
then A46: C meets Cl (RightComp (Span C,i)) by A13, XBOOLE_1:63;
A47: Cl (RightComp (Span C,i)) = (RightComp (Span C,i)) \/ (L~ (Span C,i)) by GOBRD14:31;
C misses L~ (Span C,i) by A1, Th9;
then A48: C meets RightComp (Span C,i) by A46, A47, XBOOLE_1:70;
A49: RightComp (Span C,i) is_a_component_of D by GOBOARD9:def 2;
D = (RightComp (Span C,i)) \/ (LeftComp (Span C,i)) by GOBRD12:11;
then LeftComp (Span C,i) c= D by XBOOLE_1:7;
then A50: C c= D by A45, XBOOLE_1:1;
A51: LeftComp (Span C,i) is_a_component_of D by GOBOARD9:def 1;
C meets C ;
then C meets LeftComp (Span C,i) by A1, Th12, XBOOLE_1:63;
hence contradiction by A48, A49, A50, A51, JORDAN9:3, SPRECT_4:7; :: thesis: verum