let i, m, n be Nat; :: thesis: for D being compact non horizontal non vertical Subset of (TOP-REAL 2) st 2 <= m & m + 1 < len (Gauge (D,i)) & 2 <= n & n + 1 < len (Gauge (D,i)) holds
cell ((Gauge (D,i)),m,n) = (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)))

let D be compact non horizontal non vertical Subset of (TOP-REAL 2); :: thesis: ( 2 <= m & m + 1 < len (Gauge (D,i)) & 2 <= n & n + 1 < len (Gauge (D,i)) implies cell ((Gauge (D,i)),m,n) = (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) )
set I = Gauge (D,i);
set J = Gauge (D,(i + 1));
set z = N-bound D;
set e = E-bound D;
set s = S-bound D;
set w = W-bound D;
assume that
A1: 2 <= m and
A2: m + 1 < len (Gauge (D,i)) and
A3: 2 <= n and
A4: n + 1 < len (Gauge (D,i)) ; :: thesis: cell ((Gauge (D,i)),m,n) = (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)))
A5: len (Gauge (D,(i + 1))) = width (Gauge (D,(i + 1))) by JORDAN8:def 1;
A6: (2 * n) - 3 < (2 * n) - 2 by XREAL_1:15;
(N-bound D) - (S-bound D) >= 0 by SPRECT_1:22, XREAL_1:48;
then (((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((2 * n) - 3) <= (((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((2 * n) - 2) by A6, XREAL_1:64;
then A7: (S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((2 * n) - 3)) <= (S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((2 * n) - 2)) by XREAL_1:6;
A8: m <= m + 1 by NAT_1:11;
A9: ((2 * (n + 1)) -' 2) - 2 = (((2 * n) + (2 * 1)) -' 2) - 2
.= (2 * n) - 2 by NAT_D:34 ;
A10: 1 <= ((2 * m) -' 2) + 1 by NAT_1:11;
A11: 1 <= len (Gauge (D,(i + 1))) by GOBRD11:34;
A12: 1 <= n by A3, XXREAL_0:2;
then A13: 1 <= (2 * n) -' 1 by Lm12;
(2 * n) -' 1 <= 2 * n by NAT_D:35;
then A14: 1 <= 2 * n by A13, XXREAL_0:2;
A15: ((2 * n) -' 1) + 1 = 2 * n by A12, Lm12, NAT_D:43;
A16: (2 * n) -' 1 < len (Gauge (D,(i + 1))) by A4, Lm15;
then ((2 * n) -' 1) + 1 <= len (Gauge (D,(i + 1))) by NAT_1:13;
then [1,(2 * n)] in Indices (Gauge (D,(i + 1))) by A5, A15, A11, A14, MATRIX_0:30;
then A17: ((Gauge (D,(i + 1))) * (1,(2 * n))) `2 = |[((W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * (1 - 2))),((S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((2 * n) - 2)))]| `2 by JORDAN8:def 1
.= (S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((2 * n) - 2)) by EUCLID:52 ;
A18: (2 * m) -' 1 = (2 * m) - 1 by A1, Lm8, XXREAL_0:2;
A19: (((2 * m) -' 2) + 1) - 2 = (2 * m) - 3 by A1, Lm14;
A20: 1 <= ((2 * n) -' 2) + 1 by NAT_1:11;
A21: (2 * m) -' 1 < len (Gauge (D,(i + 1))) by A2, Lm15;
A22: n <= n + 1 by NAT_1:11;
A23: ((2 * n) -' 2) + 1 = (2 * n) -' 1 by A3, Lm9, XXREAL_0:2;
A24: ((2 * (m + 1)) -' 2) - 2 = (((2 * m) + (2 * 1)) -' 2) - 2
.= (2 * m) - 2 by NAT_D:34 ;
A25: m < len (Gauge (D,i)) by A2, NAT_1:13;
then m < (2 |^ i) + 3 by JORDAN8:def 1;
then (2 * m) -' 2 < (2 |^ (i + 1)) + 3 by Lm13;
then A26: (2 * m) -' 2 < len (Gauge (D,(i + 1))) by JORDAN8:def 1;
then ((2 * m) -' 2) + 1 <= len (Gauge (D,(i + 1))) by NAT_1:13;
then [(((2 * m) -' 2) + 1),1] in Indices (Gauge (D,(i + 1))) by A5, A11, A10, MATRIX_0:30;
then A27: ((Gauge (D,(i + 1))) * ((((2 * m) -' 2) + 1),1)) `1 = |[((W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((((2 * m) -' 2) + 1) - 2))),((S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * (1 - 2)))]| `1 by JORDAN8:def 1
.= (W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((((2 * m) -' 2) + 1) - 2)) by EUCLID:52 ;
A28: 1 <= m by A1, XXREAL_0:2;
then A29: 1 < len (Gauge (D,i)) by A25, XXREAL_0:2;
then A30: ((Gauge (D,i)) * (m,1)) `1 = ((Gauge (D,(i + 1))) * (((2 * m) -' 2),1)) `1 by A1, A25, A11, Th3;
A31: len (Gauge (D,i)) = width (Gauge (D,i)) by JORDAN8:def 1;
then A32: n < width (Gauge (D,i)) by A4, NAT_1:13;
then A33: ((Gauge (D,i)) * (1,n)) `2 = ((Gauge (D,(i + 1))) * (1,((2 * n) -' 2))) `2 by A3, A31, A29, A11, Th4;
A34: 1 <= (2 * m) -' 2 by A1, Lm11;
then A35: cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)) = { |[r,q]| where r, q is Real : ( ((Gauge (D,(i + 1))) * (((2 * m) -' 2),1)) `1 <= r & r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 2) + 1),1)) `1 & ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 <= q & q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 1) + 1))) `2 ) } by A5, A13, A26, A16, GOBRD11:32;
(2 * m) -' 2 = (2 * m) - 2 by A1, Lm7;
then (2 * m) -' 2 < (2 * m) -' 1 by A18, XREAL_1:15;
then A36: ((Gauge (D,(i + 1))) * (((2 * m) -' 2),1)) `1 < ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 by A5, A11, A34, A21, GOBOARD5:3;
A37: (2 * n) -' 1 = (2 * n) - 1 by A3, Lm8, XXREAL_0:2;
A38: (((2 * n) -' 2) + 1) - 2 = (2 * n) - 3 by A3, Lm14;
n < (2 |^ i) + 3 by A31, A32, JORDAN8:def 1;
then (2 * n) -' 2 < (2 |^ (i + 1)) + 3 by Lm13;
then A39: (2 * n) -' 2 < width (Gauge (D,(i + 1))) by A5, JORDAN8:def 1;
then ((2 * n) -' 2) + 1 <= len (Gauge (D,(i + 1))) by A5, NAT_1:13;
then [1,(((2 * n) -' 2) + 1)] in Indices (Gauge (D,(i + 1))) by A5, A11, A20, MATRIX_0:30;
then A40: ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 2) + 1))) `2 = |[((W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * (1 - 2))),((S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((((2 * n) -' 2) + 1) - 2)))]| `2 by JORDAN8:def 1
.= (S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * ((((2 * n) -' 2) + 1) - 2)) by EUCLID:52 ;
A41: 1 <= (2 * n) -' 2 by A3, Lm11;
then A42: cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2)) = { |[r,q]| where r, q is Real : ( ((Gauge (D,(i + 1))) * (((2 * m) -' 2),1)) `1 <= r & r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 2) + 1),1)) `1 & ((Gauge (D,(i + 1))) * (1,((2 * n) -' 2))) `2 <= q & q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 2) + 1))) `2 ) } by A34, A26, A39, GOBRD11:32;
A43: 1 <= (2 * m) -' 1 by A28, Lm12;
then A44: cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)) = { |[r,q]| where r, q is Real : ( ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 <= r & r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 1) + 1),1)) `1 & ((Gauge (D,(i + 1))) * (1,((2 * n) -' 2))) `2 <= q & q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 2) + 1))) `2 ) } by A41, A39, A21, GOBRD11:32;
A45: cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)) = { |[r,q]| where r, q is Real : ( ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 <= r & r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 1) + 1),1)) `1 & ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 <= q & q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 1) + 1))) `2 ) } by A5, A13, A43, A16, A21, GOBRD11:32;
A46: cell ((Gauge (D,i)),m,n) = { |[r,q]| where r, q is Real : ( ((Gauge (D,i)) * (m,1)) `1 <= r & r <= ((Gauge (D,i)) * ((m + 1),1)) `1 & ((Gauge (D,i)) * (1,n)) `2 <= q & q <= ((Gauge (D,i)) * (1,(n + 1))) `2 ) } by A28, A12, A25, A32, GOBRD11:32;
1 <= n + 1 by NAT_1:11;
then [1,(n + 1)] in Indices (Gauge (D,i)) by A4, A31, A29, MATRIX_0:30;
then A47: ((Gauge (D,i)) * (1,(n + 1))) `2 = |[((W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ i)) * (1 - 2))),((S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ i)) * ((n + 1) - 2)))]| `2 by JORDAN8:def 1
.= (S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ i)) * ((n + 1) - 2)) by EUCLID:52
.= (S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * (((2 * (n + 1)) -' 2) - 2)) by A3, A22, Lm10, XXREAL_0:2 ;
1 <= m + 1 by NAT_1:11;
then [(m + 1),1] in Indices (Gauge (D,i)) by A2, A31, A29, MATRIX_0:30;
then A48: ((Gauge (D,i)) * ((m + 1),1)) `1 = |[((W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ i)) * ((m + 1) - 2))),((S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ i)) * (1 - 2)))]| `1 by JORDAN8:def 1
.= (W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ i)) * ((m + 1) - 2)) by EUCLID:52
.= (W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * (((2 * (m + 1)) -' 2) - 2)) by A1, A8, Lm10, XXREAL_0:2 ;
(2 * n) -' 2 = (2 * n) - 2 by A3, Lm7;
then (2 * n) -' 2 < (2 * n) -' 1 by A37, XREAL_1:15;
then A49: ((Gauge (D,(i + 1))) * (1,((2 * n) -' 2))) `2 < ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 by A5, A11, A41, A16, GOBOARD5:4;
A50: ((2 * m) -' 1) + 1 = 2 * m by A28, Lm12, NAT_D:43;
(2 * m) -' 1 <= 2 * m by NAT_D:35;
then A51: 1 <= 2 * m by A43, XXREAL_0:2;
((2 * m) -' 1) + 1 <= len (Gauge (D,(i + 1))) by A21, NAT_1:13;
then [(2 * m),1] in Indices (Gauge (D,(i + 1))) by A5, A50, A11, A51, MATRIX_0:30;
then A52: ((Gauge (D,(i + 1))) * ((2 * m),1)) `1 = |[((W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((2 * m) - 2))),((S-bound D) + ((((N-bound D) - (S-bound D)) / (2 |^ (i + 1))) * (1 - 2)))]| `1 by JORDAN8:def 1
.= (W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((2 * m) - 2)) by EUCLID:52 ;
A53: ((2 * m) -' 2) + 1 = (2 * m) -' 1 by A1, Lm9, XXREAL_0:2;
thus cell ((Gauge (D,i)),m,n) c= (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) :: according to XBOOLE_0:def 10 :: thesis: (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) c= cell ((Gauge (D,i)),m,n)
proof
let x be object ; :: according to TARSKI:def 3 :: thesis: ( not x in cell ((Gauge (D,i)),m,n) or x in (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) )
assume x in cell ((Gauge (D,i)),m,n) ; :: thesis: x in (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)))
then consider r, q being Real such that
A54: x = |[r,q]| and
A55: ((Gauge (D,i)) * (m,1)) `1 <= r and
A56: r <= ((Gauge (D,i)) * ((m + 1),1)) `1 and
A57: ((Gauge (D,i)) * (1,n)) `2 <= q and
A58: q <= ((Gauge (D,i)) * (1,(n + 1))) `2 by A46;
( ( r <= ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 & q <= ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 ) or ( r >= ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 & q <= ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 ) or ( r <= ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 & q >= ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 ) or ( r >= ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 & q >= ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 ) ) ;
then ( |[r,q]| in cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2)) or |[r,q]| in cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)) or |[r,q]| in cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)) or |[r,q]| in cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)) ) by A53, A23, A24, A9, A50, A15, A42, A44, A35, A45, A52, A17, A48, A47, A30, A33, A55, A56, A57, A58;
hence x in (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) by A54, Lm3; :: thesis: verum
end;
let x be object ; :: according to TARSKI:def 3 :: thesis: ( not x in (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) or x in cell ((Gauge (D,i)),m,n) )
A59: (2 * m) - 3 < (2 * m) - 2 by XREAL_1:15;
(E-bound D) - (W-bound D) >= 0 by SPRECT_1:21, XREAL_1:48;
then (((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((2 * m) - 3) <= (((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((2 * m) - 2) by A59, XREAL_1:64;
then A60: (W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((2 * m) - 3)) <= (W-bound D) + ((((E-bound D) - (W-bound D)) / (2 |^ (i + 1))) * ((2 * m) - 2)) by XREAL_1:6;
assume A61: x in (((cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)))) \/ (cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1))) ; :: thesis: x in cell ((Gauge (D,i)),m,n)
per cases ( x in cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2)) or x in cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)) or x in cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)) or x in cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)) ) by A61, Lm3;
suppose x in cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 2)) ; :: thesis: x in cell ((Gauge (D,i)),m,n)
then consider r, q being Real such that
A62: x = |[r,q]| and
A63: ((Gauge (D,(i + 1))) * (((2 * m) -' 2),1)) `1 <= r and
A64: r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 2) + 1),1)) `1 and
A65: ((Gauge (D,(i + 1))) * (1,((2 * n) -' 2))) `2 <= q and
A66: q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 2) + 1))) `2 by A42;
A67: q <= ((Gauge (D,i)) * (1,(n + 1))) `2 by A38, A9, A7, A40, A47, A66, XXREAL_0:2;
r <= ((Gauge (D,i)) * ((m + 1),1)) `1 by A19, A24, A60, A27, A48, A64, XXREAL_0:2;
hence x in cell ((Gauge (D,i)),m,n) by A46, A30, A33, A62, A63, A65, A67; :: thesis: verum
end;
suppose x in cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 2)) ; :: thesis: x in cell ((Gauge (D,i)),m,n)
then consider r, q being Real such that
A68: x = |[r,q]| and
A69: ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 <= r and
A70: r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 1) + 1),1)) `1 and
A71: ((Gauge (D,(i + 1))) * (1,((2 * n) -' 2))) `2 <= q and
A72: q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 2) + 1))) `2 by A44;
A73: ((Gauge (D,i)) * (m,1)) `1 <= r by A30, A36, A69, XXREAL_0:2;
q <= ((Gauge (D,i)) * (1,(n + 1))) `2 by A38, A9, A7, A40, A47, A72, XXREAL_0:2;
hence x in cell ((Gauge (D,i)),m,n) by A24, A50, A46, A52, A48, A33, A68, A70, A71, A73; :: thesis: verum
end;
suppose x in cell ((Gauge (D,(i + 1))),((2 * m) -' 2),((2 * n) -' 1)) ; :: thesis: x in cell ((Gauge (D,i)),m,n)
then consider r, q being Real such that
A74: x = |[r,q]| and
A75: ((Gauge (D,(i + 1))) * (((2 * m) -' 2),1)) `1 <= r and
A76: r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 2) + 1),1)) `1 and
A77: ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 <= q and
A78: q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 1) + 1))) `2 by A35;
A79: ((Gauge (D,i)) * (1,n)) `2 <= q by A33, A49, A77, XXREAL_0:2;
r <= ((Gauge (D,i)) * ((m + 1),1)) `1 by A19, A24, A60, A27, A48, A76, XXREAL_0:2;
hence x in cell ((Gauge (D,i)),m,n) by A9, A15, A46, A17, A47, A30, A74, A75, A78, A79; :: thesis: verum
end;
suppose x in cell ((Gauge (D,(i + 1))),((2 * m) -' 1),((2 * n) -' 1)) ; :: thesis: x in cell ((Gauge (D,i)),m,n)
then consider r, q being Real such that
A80: x = |[r,q]| and
A81: ((Gauge (D,(i + 1))) * (((2 * m) -' 1),1)) `1 <= r and
A82: r <= ((Gauge (D,(i + 1))) * ((((2 * m) -' 1) + 1),1)) `1 and
A83: ((Gauge (D,(i + 1))) * (1,((2 * n) -' 1))) `2 <= q and
A84: q <= ((Gauge (D,(i + 1))) * (1,(((2 * n) -' 1) + 1))) `2 by A45;
A85: ((Gauge (D,i)) * (1,n)) `2 <= q by A33, A49, A83, XXREAL_0:2;
((Gauge (D,i)) * (m,1)) `1 <= r by A30, A36, A81, XXREAL_0:2;
hence x in cell ((Gauge (D,i)),m,n) by A24, A9, A50, A15, A46, A52, A17, A48, A47, A80, A82, A84, A85; :: thesis: verum
end;
end;