| sgn(bits) = boolvar ' + boolvar ' + bits0 ⊦ |
∀ boolvar, bits1. sgn(bits0) ≠ boolvar ' + boolvar ' + bits1 ⊦ sgn(boolvar + bits0) ≠ boolvar0 ' + boolvar0 ' + bits1
Used simplifier rules: sgn-empty: ⊦ sgn([]) = [];%bitlist freely generated by [], +;;% ⊦ ¬ bits + bits0 ≠ [] ↔ bits = [] ∧ bits0 = [];% ⊦ boolvar ' ≠ [];% ⊦ (bits + bits0) + bits1 = bits + bits0 + bits1;