Used simplifier rules: minus-left: ⊦ ~ i * j = ~(i * j);%associativity: ⊦ i * j * j0 = (i * j) * j0;%commutativity: ⊦ i * j = j * i;% ⊦ ~ ~ i = i; (s)% ⊦ 0 < ~ i ↔ i < 0; (s)