let x, y, c be set ; ( x <> [<*y,c*>,and2 ] & y <> [<*x,c*>,and2a ] & c <> [<*x,y*>,and2a ] & c <> [<*x,y*>,'xor' ] implies InputVertices (BitSubtracterWithBorrowStr x,y,c) = {x,y,c} )
assume that
A1:
x <> [<*y,c*>,and2 ]
and
A2:
y <> [<*x,c*>,and2a ]
and
A3:
c <> [<*x,y*>,and2a ]
and
A4:
c <> [<*x,y*>,'xor' ]
; InputVertices (BitSubtracterWithBorrowStr x,y,c) = {x,y,c}
A5:
InputVertices (2GatesCircStr x,y,c,'xor' ) = {x,y,c}
by A4, FACIRC_1:57;
InputVertices (BorrowStr x,y,c) = {x,y,c}
by A1, A2, A3, Th15;
hence
InputVertices (BitSubtracterWithBorrowStr x,y,c) = {x,y,c}
by A5, CIRCCOMB:55, FACIRC_2:22; verum