⊦ ¬ b < a → ins≤(a, b ' + x) = a + b + x
Used simplifier rules: ⊦ x + [] = x; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a + x = a ' + x; (s) Used terms: b, a, []