| ∀ a. a ∈ ins≤(a, x0) ⊦ a ∈ ins≤(a, a0 ' + x0) |
a0 < a, ∀ a. a ∈ ins≤(a, x0) ⊦ a ∈ ins≤(a, a0 ' + x0)
Used simplifier rules: ins-y: ⊦ ¬ b < a → ins≤(a, b ' + x) = a + b + x;% ⊦ a + x = a ' + x; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a ∈ b ' + x ↔ ¬(a ≠ b ∧ ¬ a ∈ x); (ss) Used formulas: a0 < a