let n be Element of NAT ; :: thesis: for C being connected compact non horizontal non vertical Subset of (TOP-REAL 2)
for i, j, k being Element of NAT st 1 <= j & j <= k & k <= len (Gauge C,n) & 1 <= i & i <= width (Gauge C,n) & (Gauge C,n) * j,i in L~ (Lower_Seq C,n) holds
ex j1 being Element of NAT st
( j <= j1 & j1 <= k & (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)} )

let C be connected compact non horizontal non vertical Subset of (TOP-REAL 2); :: thesis: for i, j, k being Element of NAT st 1 <= j & j <= k & k <= len (Gauge C,n) & 1 <= i & i <= width (Gauge C,n) & (Gauge C,n) * j,i in L~ (Lower_Seq C,n) holds
ex j1 being Element of NAT st
( j <= j1 & j1 <= k & (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)} )

let i, j, k be Element of NAT ; :: thesis: ( 1 <= j & j <= k & k <= len (Gauge C,n) & 1 <= i & i <= width (Gauge C,n) & (Gauge C,n) * j,i in L~ (Lower_Seq C,n) implies ex j1 being Element of NAT st
( j <= j1 & j1 <= k & (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)} ) )

assume that
A1: 1 <= j and
A2: j <= k and
A3: k <= len (Gauge C,n) and
A4: 1 <= i and
A5: i <= width (Gauge C,n) and
A6: (Gauge C,n) * j,i in L~ (Lower_Seq C,n) ; :: thesis: ex j1 being Element of NAT st
( j <= j1 & j1 <= k & (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)} )

set G = Gauge C,n;
A7: k >= 1 by A1, A2, XXREAL_0:2;
then A8: [k,i] in Indices (Gauge C,n) by A3, A4, A5, MATRIX_1:37;
set X = (LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n));
A9: (Gauge C,n) * j,i in LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i) by RLTOPSP1:69;
then reconsider X1 = (LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) as non empty compact Subset of (TOP-REAL 2) by A6, PSCOMP_1:64, XBOOLE_0:def 4;
A10: LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i) meets L~ (Lower_Seq C,n) by A6, A9, XBOOLE_0:3;
set s = ((Gauge C,n) * 1,i) `2 ;
set e = (Gauge C,n) * k,i;
set f = (Gauge C,n) * j,i;
set w2 = sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))));
A11: len (Gauge C,n) = width (Gauge C,n) by JORDAN8:def 1;
then A12: j <= width (Gauge C,n) by A2, A3, XXREAL_0:2;
then [j,i] in Indices (Gauge C,n) by A1, A4, A5, A11, MATRIX_1:37;
then consider j1 being Element of NAT such that
A13: j <= j1 and
A14: j1 <= k and
A15: ((Gauge C,n) * j1,i) `1 = sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)))) by A2, A10, A8, JORDAN1F:4, JORDAN1G:5;
set q = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|;
A16: 1 <= j1 by A1, A13, XXREAL_0:2;
take j1 ; :: thesis: ( j <= j1 & j1 <= k & (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)} )
thus ( j <= j1 & j1 <= k ) by A13, A14; :: thesis: (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)}
consider pp being set such that
A17: pp in E-most X1 by XBOOLE_0:def 1;
reconsider pp = pp as Point of (TOP-REAL 2) by A17;
A18: pp in (LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) by A17, XBOOLE_0:def 4;
then A19: pp in L~ (Lower_Seq C,n) by XBOOLE_0:def 4;
A20: j1 <= width (Gauge C,n) by A3, A11, A14, XXREAL_0:2;
then A21: ((Gauge C,n) * j1,i) `2 = ((Gauge C,n) * 1,i) `2 by A4, A5, A11, A16, GOBOARD5:2;
then A22: |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| = (Gauge C,n) * j1,i by A15, EUCLID:57;
then A23: |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `1 <= ((Gauge C,n) * k,i) `1 by A3, A4, A5, A14, A16, SPRECT_3:25;
A24: ((Gauge C,n) * k,i) `2 = ((Gauge C,n) * 1,i) `2 by A3, A4, A5, A7, GOBOARD5:2;
then ((Gauge C,n) * j,i) `2 = ((Gauge C,n) * k,i) `2 by A1, A4, A5, A11, A12, GOBOARD5:2;
then A25: LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i) is horizontal by SPPOL_1:36;
A26: |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `1 = E-bound ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))) by A15, A22, SPRECT_1:51
.= (E-min ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)))) `1 by EUCLID:56
.= pp `1 by A17, PSCOMP_1:108 ;
pp in LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i) by A18, XBOOLE_0:def 4;
then pp `2 = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `2 by A24, A21, A22, A25, SPPOL_1:63;
then A27: |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| in L~ (Lower_Seq C,n) by A19, A26, TOPREAL3:11;
for x being set holds
( x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n)) iff x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| )
proof
let x be set ; :: thesis: ( x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n)) iff x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| )
thus ( x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n)) implies x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| ) :: thesis: ( x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| implies x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n)) )
proof
A28: ((Gauge C,n) * j,i) `1 <= |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `1 by A1, A4, A5, A11, A13, A20, A22, SPRECT_3:25;
((Gauge C,n) * j,i) `2 = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `2 by A1, A4, A5, A11, A12, A21, A22, GOBOARD5:2;
then A29: |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| in LSeg ((Gauge C,n) * k,i),((Gauge C,n) * j,i) by A24, A21, A22, A23, A28, GOBOARD7:9;
(Gauge C,n) * k,i in LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i) by RLTOPSP1:69;
then A30: LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| c= LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i) by A29, TOPREAL1:12;
reconsider EE = (LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) as compact Subset of (TOP-REAL 2) by PSCOMP_1:64;
reconsider E0 = proj1 .: EE as compact Subset of REAL by Th4;
assume A31: x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n)) ; :: thesis: x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|
then reconsider pp = x as Point of (TOP-REAL 2) ;
A32: pp in LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| by A31, XBOOLE_0:def 4;
then A33: pp `1 >= |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `1 by A23, TOPREAL1:9;
pp in L~ (Lower_Seq C,n) by A31, XBOOLE_0:def 4;
then pp in EE by A32, A30, XBOOLE_0:def 4;
then proj1 . pp in E0 by FUNCT_2:43;
then A34: pp `1 in E0 by PSCOMP_1:def 28;
E0 is bounded by RCOMP_1:28;
then E0 is bounded_above by XXREAL_2:def 11;
then |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `1 >= pp `1 by A15, A22, A34, SEQ_4:def 4;
then A35: pp `1 = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `1 by A33, XXREAL_0:1;
pp `2 = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| `2 by A24, A21, A22, A32, GOBOARD7:6;
hence x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| by A35, TOPREAL3:11; :: thesis: verum
end;
assume A36: x = |[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| ; :: thesis: x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n))
then x in LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]| by RLTOPSP1:69;
hence x in (LSeg ((Gauge C,n) * k,i),|[(sup (proj1 .: ((LSeg ((Gauge C,n) * j,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n))))),(((Gauge C,n) * 1,i) `2 )]|) /\ (L~ (Lower_Seq C,n)) by A27, A36, XBOOLE_0:def 4; :: thesis: verum
end;
hence (LSeg ((Gauge C,n) * j1,i),((Gauge C,n) * k,i)) /\ (L~ (Lower_Seq C,n)) = {((Gauge C,n) * j1,i)} by A22, TARSKI:def 1; :: thesis: verum