theorem :: BINARI_2:18

for m being non zero Nat
for z1, z2 being Tuple of m, BOOLEAN
for d1, d2 being Element of BOOLEAN holds (z1 ^ <*d1*>) - (z2 ^ <*d2*>) = (z1 + (Neg2 z2)) ^ <*(((d1 'xor' ('not' d2)) 'xor' (add_ovfl (('not' z2),(Bin1 m)))) 'xor' (add_ovfl (z1,(Neg2 z2))))*>