specification using olist-act functions ins≤ : elem × list → list; merge : list × list → list; predicates ordered≤ : list; ordered< : list; variables x : list; y : list; z : list; a : elem; b : elem; c : elem; n : nat; axioms le-e: ordered≤([]); used for: s, ls; le-o: ordered≤(a '); used for: s, ls; le-r: ordered≤(a ' + b ' + x) ↔ ¬ b < a ∧ ordered≤(b ' + x); used for: ws, lws; ls-e: ordered<([]); used for: s, ls; ls-o: ordered<(a '); used for: s, ls; ls-r: ordered<(a ' + b ' + x) ↔ a < b ∧ ordered<(b ' + x); used for: ws, lws; ins-e: ins≤(a, []) = a '; used for: s, ls; ins-y: ¬ b < a → ins≤(a, b ' + x) = a + b + x; used for: s, ls; ins-n: b < a → ins≤(a, b ' + x) = b + ins≤(a, x); used for: s, ls, lc; merge-empty: merge([], x) = x; used for: s, ls; merge-rec: merge(a ' + x0, x) = ins≤(a, merge(x0, x)); used for: s, ls; end specification