:: deftheorem Def16 defines or3b TWOSCOMP:def 16 :
for b₁ being Function of (3 -tuples_on BOOLEAN),BOOLEAN holds
( b₁ = or3b iff for x, y, z being Element of BOOLEAN holds b₁ . <*x,y,z*> = (('not' x) 'or' ('not' y)) 'or' z );