let G be Go-board; :: thesis: ( 1 < width G & 1 < len G implies LSeg (((G * (1,1)) - |[1,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) c= ((Int (cell (G,0,0))) \/ (Int (cell (G,1,0)))) \/ {((G * (1,1)) - |[0,1]|)} )
assume that
A1: 1 < width G and
A2: 1 < len G ; :: thesis: LSeg (((G * (1,1)) - |[1,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) c= ((Int (cell (G,0,0))) \/ (Int (cell (G,1,0)))) \/ {((G * (1,1)) - |[0,1]|)}
set q2 = G * (1,1);
set q3 = G * (2,1);
set r = 1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1);
A3: 0 + (1 + 1) <= len G by A2, NAT_1:13;
then A4: (G * (1,1)) `2 = (G * (2,1)) `2 by A1, GOBOARD5:1;
(G * (1,1)) `1 < (G * (2,1)) `1 by A1, A3, GOBOARD5:3;
then A5: ((G * (2,1)) `1) - ((G * (1,1)) `1) > 0 by XREAL_1:50;
then 1 < ((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1 by XREAL_1:29, XREAL_1:129;
then A6: 1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1) < 1 by XREAL_1:212;
A7: (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) - |[1,1]|)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|))) `2 = (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) - |[1,1]|)) `2) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `2) by Lm1
.= ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (((G * (1,1)) - |[1,1]|) `2)) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `2) by Lm3
.= ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (((G * (1,1)) - |[1,1]|) `2)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|) `2)) by Lm3
.= ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (((G * (1,1)) `2) - (|[1,1]| `2))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|) `2)) by Lm2
.= ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (((G * (1,1)) `2) - (|[1,1]| `2))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) `2) - (|[0,1]| `2))) by Lm2
.= ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (((G * (1,1)) `2) - 1)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) `2) - (|[0,1]| `2))) by EUCLID:52
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `2)) - ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * 1)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) `2) - 1)) by EUCLID:52
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `2)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) `2))) - ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) + (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)))
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `2)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((1 / 2) * (((G * (1,1)) + (G * (2,1))) `2)))) - 1 by Lm3
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `2)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((1 / 2) * (((G * (1,1)) `2) + ((G * (1,1)) `2))))) - 1 by A4, Lm1
.= ((G * (1,1)) `2) - (|[0,1]| `2) by EUCLID:52
.= ((G * (1,1)) - |[0,1]|) `2 by Lm2 ;
A8: (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((1 / 2) * ((G * (2,1)) `1))) - ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((1 / 2) * ((G * (1,1)) `1)))) + (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) = (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)
.= 1 by A5, XCMPLX_1:106 ;
(((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) - |[1,1]|)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|))) `1 = (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) - |[1,1]|)) `1) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `1) by Lm1
.= ((((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (G * (1,1))) - ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * |[1,1]|)) `1) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `1) by RLVECT_1:34
.= ((((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (G * (1,1))) `1) - (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * |[1,1]|) `1)) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `1) by Lm2
.= ((((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (G * (1,1))) `1) - ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (|[1,1]| `1))) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `1) by Lm3
.= ((((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * (G * (1,1))) `1) - ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * 1)) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `1) by EUCLID:52
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `1)) - ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * 1)) + (((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) `1) by Lm3
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `1)) - (1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|) `1)) by Lm3
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `1)) - (1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) `1) - (|[0,1]| `1))) by Lm2
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `1)) - (1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((((1 / 2) * ((G * (1,1)) + (G * (2,1)))) `1) - 0)) by EUCLID:52
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `1)) - (1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((1 / 2) * (((G * (1,1)) + (G * (2,1))) `1))) by Lm3
.= (((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) `1)) - (1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)))) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * ((1 / 2) * (((G * (1,1)) `1) + ((G * (2,1)) `1)))) by Lm1
.= ((G * (1,1)) `1) - 0 by A8
.= ((G * (1,1)) `1) - (|[0,1]| `1) by EUCLID:52
.= ((G * (1,1)) - |[0,1]|) `1 by Lm2 ;
then ((1 - (1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1))) * ((G * (1,1)) - |[1,1]|)) + ((1 / (((1 / 2) * (((G * (2,1)) `1) - ((G * (1,1)) `1))) + 1)) * (((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) = |[(((G * (1,1)) - |[0,1]|) `1),(((G * (1,1)) - |[0,1]|) `2)]| by A7, EUCLID:53
.= (G * (1,1)) - |[0,1]| by EUCLID:53 ;
then (G * (1,1)) - |[0,1]| in LSeg (((G * (1,1)) - |[1,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) by A5, A6;
then A9: LSeg (((G * (1,1)) - |[1,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) = (LSeg (((G * (1,1)) - |[1,1]|),((G * (1,1)) - |[0,1]|))) \/ (LSeg (((G * (1,1)) - |[0,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|))) by TOPREAL1:5;
set I1 = Int (cell (G,0,0));
set I2 = Int (cell (G,1,0));
(0 + 1) + 1 = 0 + (1 + 1) ;
then A10: LSeg (((G * (1,1)) - |[0,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) c= (Int (cell (G,1,0))) \/ {((G * (1,1)) - |[0,1]|)} by A2, Th52;
A11: ((Int (cell (G,0,0))) \/ (Int (cell (G,1,0)))) \/ {((G * (1,1)) - |[0,1]|)} = (Int (cell (G,0,0))) \/ ((Int (cell (G,1,0))) \/ ({((G * (1,1)) - |[0,1]|)} \/ {((G * (1,1)) - |[0,1]|)})) by XBOOLE_1:4
.= (Int (cell (G,0,0))) \/ (((Int (cell (G,1,0))) \/ {((G * (1,1)) - |[0,1]|)}) \/ {((G * (1,1)) - |[0,1]|)}) by XBOOLE_1:4
.= ((Int (cell (G,0,0))) \/ {((G * (1,1)) - |[0,1]|)}) \/ ((Int (cell (G,1,0))) \/ {((G * (1,1)) - |[0,1]|)}) by XBOOLE_1:4 ;
LSeg (((G * (1,1)) - |[1,1]|),((G * (1,1)) - |[0,1]|)) c= (Int (cell (G,0,0))) \/ {((G * (1,1)) - |[0,1]|)} by Th60;
hence LSeg (((G * (1,1)) - |[1,1]|),(((1 / 2) * ((G * (1,1)) + (G * (2,1)))) - |[0,1]|)) c= ((Int (cell (G,0,0))) \/ (Int (cell (G,1,0)))) \/ {((G * (1,1)) - |[0,1]|)} by A9, A10, A11, XBOOLE_1:13; :: thesis: verum