:: deftheorem HamDef defines Hamacher_norm FUZNORM1:def 13 :
for b₁ being BinOp of [.0,1.] holds
( b₁ = Hamacher_norm iff for a, b being Element of [.0,1.] holds b₁ . (a,b) = (a * b) / ((a + b) - (a * b)) );