let ap, bm, cp, dm be FinSequence; 0 -BitFTA1CarryOutput (ap,bm,cp,dm) = [<*>,((0 -tuples_on BOOLEAN) --> FALSE)]
consider h being ManySortedSet of NAT such that
A1:
0 -BitFTA1CarryOutput (ap,bm,cp,dm) = h . 0
and
A2:
h . 0 = [<*>,((0 -tuples_on BOOLEAN) --> FALSE)]
and
for k being Nat holds h . (k + 1) = BitFTA1CarryOutput ((ap . (k + 1)),(bm . (k + 1)),(cp . (k + 1)),(dm . (k + 1)),(h . k))
by Def10;
thus
0 -BitFTA1CarryOutput (ap,bm,cp,dm) = [<*>,((0 -tuples_on BOOLEAN) --> FALSE)]
by A1, A2; verum