let i be Nat; :: thesis: for G being Go-board st 1 <= i & i < len G holds
LSeg ((((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[0,1]|),((G * (i,(width G))) + |[0,1]|)) c= (Int (cell (G,i,(width G)))) \/ {((G * (i,(width G))) + |[0,1]|)}
let G be Go-board; :: thesis: ( 1 <= i & i < len G implies LSeg ((((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[0,1]|),((G * (i,(width G))) + |[0,1]|)) c= (Int (cell (G,i,(width G)))) \/ {((G * (i,(width G))) + |[0,1]|)} )
assume that
A1: 1 <= i and
A2: i < len G ; :: thesis: LSeg ((((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[0,1]|),((G * (i,(width G))) + |[0,1]|)) c= (Int (cell (G,i,(width G)))) \/ {((G * (i,(width G))) + |[0,1]|)}
let x be object ; :: according to TARSKI:def 3 :: thesis: ( not x in LSeg ((((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[0,1]|),((G * (i,(width G))) + |[0,1]|)) or x in (Int (cell (G,i,(width G)))) \/ {((G * (i,(width G))) + |[0,1]|)} )
assume A3: x in LSeg ((((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[0,1]|),((G * (i,(width G))) + |[0,1]|)) ; :: thesis: x in (Int (cell (G,i,(width G)))) \/ {((G * (i,(width G))) + |[0,1]|)}
then reconsider p = x as Point of (TOP-REAL 2) ;
consider r being Real such that
A4: p = ((1 - r) * (((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[0,1]|)) + (r * ((G * (i,(width G))) + |[0,1]|)) and
A5: 0 <= r and
A6: r <= 1 by A3;

now :: thesis: ( ( r = 1 & p in {((G * (i,(width G))) + |[0,1]|)} ) or ( r < 1 & p in Int (cell (G,i,(width G))) ) )

per cases ( r = 1 or r < 1 ) by A6, XXREAL_0:1;

case r = 1 ; :: thesis: p in {((G * (i,(width G))) + |[0,1]|)}

then p = (0. (TOP-REAL 2)) + (1 * ((G * (i,(width G))) + |[0,1]|)) by A4, RLVECT_1:10
.= 1 * ((G * (i,(width G))) + |[0,1]|) by RLVECT_1:4
.= (G * (i,(width G))) + |[0,1]| by RLVECT_1:def 8 ;
hence p in {((G * (i,(width G))) + |[0,1]|)} by TARSKI:def 1; :: thesis: verum

end;

case A7: r < 1 ; :: thesis: p in Int (cell (G,i,(width G)))

set r3 = (1 - r) * (1 / 2);
1 - r > 0 by A7, XREAL_1:50;
then A8: (1 - r) * (1 / 2) > (1 / 2) * 0 by XREAL_1:68;
set s1 = (G * (1,(width G))) `2 ;
set r1 = (G * (i,1)) `1 ;
set r2 = (G * ((i + 1),1)) `1 ;
A9: (((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * (i,1)) `1))) + (r * ((G * (i,1)) `1)) = (G * (i,1)) `1 ;
A10: i + 1 <= len G by A2, NAT_1:13;
0 <> width G by MATRIX_0:def 10;
then A11: 1 <= width G by NAT_1:14;
A12: G * (i,(width G)) = |[((G * (i,(width G))) `1),((G * (i,(width G))) `2)]| by EUCLID:53
.= |[((G * (i,(width G))) `1),((G * (1,(width G))) `2)]| by A1, A2, A11, GOBOARD5:1
.= |[((G * (i,1)) `1),((G * (1,(width G))) `2)]| by A1, A2, A11, GOBOARD5:2 ;
A13: 1 <= i + 1 by A1, NAT_1:13;
i < i + 1 by XREAL_1:29;
then A14: (G * (i,1)) `1 < (G * ((i + 1),1)) `1 by A1, A10, A11, GOBOARD5:3;
then ((G * (i,1)) `1) + ((G * ((i + 1),1)) `1) < ((G * ((i + 1),1)) `1) + ((G * ((i + 1),1)) `1) by XREAL_1:6;
then A15: ((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)) < ((1 - r) * (1 / 2)) * (((G * ((i + 1),1)) `1) + ((G * ((i + 1),1)) `1)) by A8, XREAL_1:68;
((G * (i,1)) `1) + ((G * (i,1)) `1) < ((G * (i,1)) `1) + ((G * ((i + 1),1)) `1) by A14, XREAL_1:6;
then ((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * (i,1)) `1)) < ((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)) by A8, XREAL_1:68;
then A16: ( (G * (1,(width G))) `2 < ((G * (1,(width G))) `2) + 1 & (G * (i,1)) `1 < (((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1))) + (r * ((G * (i,1)) `1)) ) by A9, XREAL_1:6, XREAL_1:29;
A17: Int (cell (G,i,(width G))) = { |[r9,s9]| where r9, s9 is Real : ( (G * (i,1)) `1 < r9 & r9 < (G * ((i + 1),1)) `1 & (G * (1,(width G))) `2 < s9 ) } by A1, A2, Th25;
A18: G * ((i + 1),(width G)) = |[((G * ((i + 1),(width G))) `1),((G * ((i + 1),(width G))) `2)]| by EUCLID:53
.= |[((G * ((i + 1),(width G))) `1),((G * (1,(width G))) `2)]| by A13, A10, A11, GOBOARD5:1
.= |[((G * ((i + 1),1)) `1),((G * (1,(width G))) `2)]| by A13, A10, A11, GOBOARD5:2 ;
A19: (((1 - r) * (1 / 2)) * (((G * ((i + 1),1)) `1) + ((G * ((i + 1),1)) `1))) + (r * ((G * ((i + 1),1)) `1)) = (G * ((i + 1),1)) `1 ;
r * ((G * (i,1)) `1) <= r * ((G * ((i + 1),1)) `1) by A5, A14, XREAL_1:64;
then A20: (((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1))) + (r * ((G * (i,1)) `1)) < (G * ((i + 1),1)) `1 by A15, A19, XREAL_1:8;
p = (((1 - r) * ((1 / 2) * ((G * (i,(width G))) + (G * ((i + 1),(width G)))))) + ((1 - r) * |[0,1]|)) + (r * ((G * (i,(width G))) + |[0,1]|)) by A4, RLVECT_1:def 5
.= ((((1 - r) * (1 / 2)) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + ((1 - r) * |[0,1]|)) + (r * ((G * (i,(width G))) + |[0,1]|)) by RLVECT_1:def 7
.= ((((1 - r) * (1 / 2)) * ((G * (i,(width G))) + (G * ((i + 1),(width G))))) + |[((1 - r) * 0),((1 - r) * 1)]|) + (r * ((G * (i,(width G))) + |[0,1]|)) by EUCLID:58
.= ((((1 - r) * (1 / 2)) * |[(((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)),(((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))]|) + |[0,(1 - r)]|) + (r * (|[((G * (i,1)) `1),((G * (1,(width G))) `2)]| + |[0,1]|)) by A18, A12, EUCLID:56
.= ((((1 - r) * (1 / 2)) * |[(((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)),(((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))]|) + |[0,(1 - r)]|) + ((r * |[((G * (i,1)) `1),((G * (1,(width G))) `2)]|) + (r * |[0,1]|)) by RLVECT_1:def 5
.= ((((1 - r) * (1 / 2)) * |[(((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)),(((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))]|) + |[0,(1 - r)]|) + (|[(r * ((G * (i,1)) `1)),(r * ((G * (1,(width G))) `2))]| + (r * |[0,1]|)) by EUCLID:58
.= ((((1 - r) * (1 / 2)) * |[(((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)),(((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))]|) + |[0,(1 - r)]|) + (|[(r * ((G * (i,1)) `1)),(r * ((G * (1,(width G))) `2))]| + |[(r * 0),(r * 1)]|) by EUCLID:58
.= ((((1 - r) * (1 / 2)) * |[(((G * (i,1)) `1) + ((G * ((i + 1),1)) `1)),(((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))]|) + |[0,(1 - r)]|) + |[((r * ((G * (i,1)) `1)) + 0),((r * ((G * (1,(width G))) `2)) + r)]| by EUCLID:56
.= (|[(((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1))),(((1 - r) * (1 / 2)) * (((G * (1,(width G))) `2) + ((G * (1,(width G))) `2)))]| + |[0,(1 - r)]|) + |[((r * ((G * (i,1)) `1)) + 0),((r * ((G * (1,(width G))) `2)) + r)]| by EUCLID:58
.= |[((((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1))) + 0),((((1 - r) * (1 / 2)) * (((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))) + (1 - r))]| + |[((r * ((G * (i,1)) `1)) + 0),((r * ((G * (1,(width G))) `2)) + r)]| by EUCLID:56
.= |[((((1 - r) * (1 / 2)) * (((G * (i,1)) `1) + ((G * ((i + 1),1)) `1))) + (r * ((G * (i,1)) `1))),(((((1 - r) * (1 / 2)) * (((G * (1,(width G))) `2) + ((G * (1,(width G))) `2))) + (1 - r)) + ((r * ((G * (1,(width G))) `2)) + r))]| by EUCLID:56 ;
hence p in Int (cell (G,i,(width G))) by A16, A20, A17; :: thesis: verum

end;

end;

end;

hence x in (Int (cell (G,i,(width G)))) \/ {((G * (i,(width G))) + |[0,1]|)} by XBOOLE_0:def 3; :: thesis: verum