let C be non empty compact non horizontal non vertical Subset of (TOP-REAL 2); :: thesis: for n, i1, i2 being Nat st 1 <= i1 & i1 + 1 <= len (Gauge C,n) & N-min C in cell (Gauge C,n),i1,((width (Gauge C,n)) -' 1) & N-min C <> (Gauge C,n) * i1,((width (Gauge C,n)) -' 1) & 1 <= i2 & i2 + 1 <= len (Gauge C,n) & N-min C in cell (Gauge C,n),i2,((width (Gauge C,n)) -' 1) & N-min C <> (Gauge C,n) * i2,((width (Gauge C,n)) -' 1) holds
i1 = i2

let n, i1, i2 be Nat; :: thesis: ( 1 <= i1 & i1 + 1 <= len (Gauge C,n) & N-min C in cell (Gauge C,n),i1,((width (Gauge C,n)) -' 1) & N-min C <> (Gauge C,n) * i1,((width (Gauge C,n)) -' 1) & 1 <= i2 & i2 + 1 <= len (Gauge C,n) & N-min C in cell (Gauge C,n),i2,((width (Gauge C,n)) -' 1) & N-min C <> (Gauge C,n) * i2,((width (Gauge C,n)) -' 1) implies i1 = i2 )
A1: ( i1 in NAT & i2 in NAT ) by ORDINAL1:def 13;
set G = Gauge C,n;
set j = (width (Gauge C,n)) -' 1;
assume that
A2: ( 1 <= i1 & i1 + 1 <= len (Gauge C,n) ) and
A3: N-min C in cell (Gauge C,n),i1,((width (Gauge C,n)) -' 1) and
A4: N-min C <> (Gauge C,n) * i1,((width (Gauge C,n)) -' 1) and
A5: ( 1 <= i2 & i2 + 1 <= len (Gauge C,n) ) and
A6: N-min C in cell (Gauge C,n),i2,((width (Gauge C,n)) -' 1) and
A7: N-min C <> (Gauge C,n) * i2,((width (Gauge C,n)) -' 1) and
A8: i1 <> i2 ; :: thesis: contradiction
A9: ( i1 < len (Gauge C,n) & i2 < len (Gauge C,n) & len (Gauge C,n) = width (Gauge C,n) ) by A2, A5, JORDAN8:def 1, NAT_1:13;
A10: cell (Gauge C,n),i1,((width (Gauge C,n)) -' 1) meets cell (Gauge C,n),i2,((width (Gauge C,n)) -' 1) by A3, A6, XBOOLE_0:3;
A11: ( len (Gauge C,n) = (2 |^ n) + 3 & len (Gauge C,n) = width (Gauge C,n) ) by JORDAN8:def 1;
A12: 2 |^ n >= n + 1 by NEWTON:104;
then len (Gauge C,n) >= (n + 1) + 3 by A11, XREAL_1:8;
then A13: ( len (Gauge C,n) >= 1 + (n + 3) & 1 + (n + 3) > 1 + 0 ) by XREAL_1:8;
then len (Gauge C,n) > 1 by XXREAL_0:2;
then A14: len (Gauge C,n) >= 1 + 1 by NAT_1:13;
then A15: 1 <= (width (Gauge C,n)) -' 1 by A9, JORDAN5B:2;
A16: ((width (Gauge C,n)) -' 1) + 1 = len (Gauge C,n) by A9, A13, XREAL_1:237, XXREAL_0:2;
then A17: (width (Gauge C,n)) -' 1 < len (Gauge C,n) by NAT_1:13;
per cases ( i1 < i2 or i2 < i1 ) by A8, XXREAL_0:1;
suppose A18: i1 < i2 ; :: thesis: contradiction
then A19: (i2 -' i1) + i1 = i2 by XREAL_1:237;
then i2 -' i1 <= 1 by A1, A9, A10, A15, A17, JORDAN8:10;
then ( i2 -' i1 < 1 or i2 -' i1 = 1 ) by XXREAL_0:1;
then ( i2 -' i1 = 0 or i2 -' i1 = 1 ) by NAT_1:14;
then (cell (Gauge C,n),i1,((width (Gauge C,n)) -' 1)) /\ (cell (Gauge C,n),i2,((width (Gauge C,n)) -' 1)) = LSeg ((Gauge C,n) * i2,((width (Gauge C,n)) -' 1)),((Gauge C,n) * i2,(((width (Gauge C,n)) -' 1) + 1)) by A1, A9, A14, A17, A18, A19, GOBOARD5:26, JORDAN5B:2;
then A20: N-min C in LSeg ((Gauge C,n) * i2,((width (Gauge C,n)) -' 1)),((Gauge C,n) * i2,(((width (Gauge C,n)) -' 1) + 1)) by A3, A6, XBOOLE_0:def 4;
A21: [i2,((width (Gauge C,n)) -' 1)] in Indices (Gauge C,n) by A5, A9, A15, A17, MATRIX_1:37;
1 <= ((width (Gauge C,n)) -' 1) + 1 by NAT_1:12;
then A22: [i2,(((width (Gauge C,n)) -' 1) + 1)] in Indices (Gauge C,n) by A5, A9, A16, MATRIX_1:37;
set x = (W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i2 - 2));
set y1 = (S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 2));
set y2 = (S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 1));
A23: (((width (Gauge C,n)) -' 1) + 1) - (1 + 1) = ((width (Gauge C,n)) -' 1) - 1 ;
A24: (Gauge C,n) * i2,((width (Gauge C,n)) -' 1) = |[((W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i2 - 2))),((S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 2)))]| by A21, JORDAN8:def 1;
(Gauge C,n) * i2,(((width (Gauge C,n)) -' 1) + 1) = |[((W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i2 - 2))),((S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 1)))]| by A22, A23, JORDAN8:def 1;
then A25: ( ((Gauge C,n) * i2,((width (Gauge C,n)) -' 1)) `1 = (W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i2 - 2)) & ((Gauge C,n) * i2,(((width (Gauge C,n)) -' 1) + 1)) `1 = (W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i2 - 2)) ) by A24, EUCLID:56;
then LSeg ((Gauge C,n) * i2,((width (Gauge C,n)) -' 1)),((Gauge C,n) * i2,(((width (Gauge C,n)) -' 1) + 1)) is vertical by SPPOL_1:37;
then A26: (N-min C) `1 = ((Gauge C,n) * i2,((width (Gauge C,n)) -' 1)) `1 by A20, SPPOL_1:64;
(width (Gauge C,n)) -' 1 = (((2 |^ n) + 2) + 1) -' 1 by A11
.= (2 |^ n) + 2 by NAT_D:34 ;
then (((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 2) = (N-bound C) - (S-bound C) by A12, XCMPLX_1:88;
hence contradiction by A7, A24, A25, A26, EUCLID:56; :: thesis: verum
end;
suppose A27: i2 < i1 ; :: thesis: contradiction
then A28: (i1 -' i2) + i2 = i1 by XREAL_1:237;
then i1 -' i2 <= 1 by A1, A9, A10, A15, A17, JORDAN8:10;
then ( i1 -' i2 < 1 or i1 -' i2 = 1 ) by XXREAL_0:1;
then ( i1 -' i2 = 0 or i1 -' i2 = 1 ) by NAT_1:14;
then (cell (Gauge C,n),i2,((width (Gauge C,n)) -' 1)) /\ (cell (Gauge C,n),i1,((width (Gauge C,n)) -' 1)) = LSeg ((Gauge C,n) * i1,((width (Gauge C,n)) -' 1)),((Gauge C,n) * i1,(((width (Gauge C,n)) -' 1) + 1)) by A1, A9, A14, A17, A27, A28, GOBOARD5:26, JORDAN5B:2;
then A29: N-min C in LSeg ((Gauge C,n) * i1,((width (Gauge C,n)) -' 1)),((Gauge C,n) * i1,(((width (Gauge C,n)) -' 1) + 1)) by A3, A6, XBOOLE_0:def 4;
A30: [i1,((width (Gauge C,n)) -' 1)] in Indices (Gauge C,n) by A2, A9, A15, A17, MATRIX_1:37;
1 <= ((width (Gauge C,n)) -' 1) + 1 by NAT_1:12;
then A31: [i1,(((width (Gauge C,n)) -' 1) + 1)] in Indices (Gauge C,n) by A2, A9, A16, MATRIX_1:37;
set x = (W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i1 - 2));
set y1 = (S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 2));
set y2 = (S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 1));
A32: (((width (Gauge C,n)) -' 1) + 1) - (1 + 1) = ((width (Gauge C,n)) -' 1) - 1 ;
A33: (Gauge C,n) * i1,((width (Gauge C,n)) -' 1) = |[((W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i1 - 2))),((S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 2)))]| by A30, JORDAN8:def 1;
(Gauge C,n) * i1,(((width (Gauge C,n)) -' 1) + 1) = |[((W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i1 - 2))),((S-bound C) + ((((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 1)))]| by A31, A32, JORDAN8:def 1;
then A34: ( ((Gauge C,n) * i1,((width (Gauge C,n)) -' 1)) `1 = (W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i1 - 2)) & ((Gauge C,n) * i1,(((width (Gauge C,n)) -' 1) + 1)) `1 = (W-bound C) + ((((E-bound C) - (W-bound C)) / (2 |^ n)) * (i1 - 2)) ) by A33, EUCLID:56;
then LSeg ((Gauge C,n) * i1,((width (Gauge C,n)) -' 1)),((Gauge C,n) * i1,(((width (Gauge C,n)) -' 1) + 1)) is vertical by SPPOL_1:37;
then A35: (N-min C) `1 = ((Gauge C,n) * i1,((width (Gauge C,n)) -' 1)) `1 by A29, SPPOL_1:64;
(width (Gauge C,n)) -' 1 = (((2 |^ n) + 2) + 1) -' 1 by A11
.= (2 |^ n) + 2 by NAT_D:34 ;
then (((N-bound C) - (S-bound C)) / (2 |^ n)) * (((width (Gauge C,n)) -' 1) - 2) = (N-bound C) - (S-bound C) by A12, XCMPLX_1:88;
hence contradiction by A4, A33, A34, A35, EUCLID:56; :: thesis: verum
end;
end;