let x, y, c be set ; ( x <> [<*y,c*>,and2 ] & y <> [<*x,c*>,and2a ] & c <> [<*x,y*>,and2a ] implies for s being State of (BorrowCirc x,y,c)
for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . c holds
( (Following s,2) . (BorrowOutput x,y,c) = ((('not' a1) '&' a2) 'or' (a2 '&' a3)) 'or' (('not' a1) '&' a3) & (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 ) )
assume that
A1:
x <> [<*y,c*>,and2 ]
and
A2:
y <> [<*x,c*>,and2a ]
and
A3:
c <> [<*x,y*>,and2a ]
; for s being State of (BorrowCirc x,y,c)
for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . c holds
( (Following s,2) . (BorrowOutput x,y,c) = ((('not' a1) '&' a2) 'or' (a2 '&' a3)) 'or' (('not' a1) '&' a3) & (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 )
let s be State of (BorrowCirc x,y,c); for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . c holds
( (Following s,2) . (BorrowOutput x,y,c) = ((('not' a1) '&' a2) 'or' (a2 '&' a3)) 'or' (('not' a1) '&' a3) & (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 )
let a1, a2, a3 be Element of BOOLEAN ; ( a1 = s . x & a2 = s . y & a3 = s . c implies ( (Following s,2) . (BorrowOutput x,y,c) = ((('not' a1) '&' a2) 'or' (a2 '&' a3)) 'or' (('not' a1) '&' a3) & (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 ) )
assume that
A4:
a1 = s . x
and
A5:
a2 = s . y
and
A6:
a3 = s . c
; ( (Following s,2) . (BorrowOutput x,y,c) = ((('not' a1) '&' a2) 'or' (a2 '&' a3)) 'or' (('not' a1) '&' a3) & (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 )
set xy = [<*x,y*>,and2a ];
set yc = [<*y,c*>,and2 ];
set cx = [<*x,c*>,and2a ];
set S = BorrowStr x,y,c;
reconsider x9 = x, y9 = y, c9 = c as Vertex of (BorrowStr x,y,c) by FSCIRC_1:6;
A7:
InputVertices (BorrowStr x,y,c) = {x,y,c}
by A1, A2, A3, Th15;
then A8:
x in InputVertices (BorrowStr x,y,c)
by ENUMSET1:def 1;
A9:
y in InputVertices (BorrowStr x,y,c)
by A7, ENUMSET1:def 1;
A10:
c in InputVertices (BorrowStr x,y,c)
by A7, ENUMSET1:def 1;
A11:
(Following s) . x9 = s . x
by A8, CIRCUIT2:def 5;
A12:
(Following s) . y9 = s . y
by A9, CIRCUIT2:def 5;
A13:
(Following s) . c9 = s . c
by A10, CIRCUIT2:def 5;
A14:
Following s,2 = Following (Following s)
by FACIRC_1:15;
A15:
(Following s) . [<*x,y*>,and2a ] = ('not' a1) '&' a2
by A4, A5, A6, Lm1;
A16:
(Following s) . [<*y,c*>,and2 ] = a2 '&' a3
by A4, A5, A6, Lm1;
(Following s) . [<*x,c*>,and2a ] = ('not' a1) '&' a3
by A4, A5, A6, Lm1;
hence
(Following s,2) . (BorrowOutput x,y,c) = ((('not' a1) '&' a2) 'or' (a2 '&' a3)) 'or' (('not' a1) '&' a3)
by A14, A15, A16, Th22; ( (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 )
thus
( (Following s,2) . [<*x,y*>,and2a ] = ('not' a1) '&' a2 & (Following s,2) . [<*y,c*>,and2 ] = a2 '&' a3 & (Following s,2) . [<*x,c*>,and2a ] = ('not' a1) '&' a3 )
by A4, A5, A6, A11, A12, A13, A14, Lm1; verum