| 2 < # s, a ∈ s, b ∈ s ⊦ b = a, #(∅ ++ a ++ b) < # s, ∃ a, b, c. a ∈ s ∧ b ∈ s ∧ c ∈ s ∧ a ≠ b ∧ a ≠ c ∧ b ≠ c |
2 < # s, 2 < #(∅ ++ a ++ b), b ∈ s, a ∈ s, # s ≤ #(∅ ++ a ++ b) ⊦ b = a, ∃ a, b, c. a ∈ s ∧ b ∈ s ∧ c ∈ s ∧ a ≠ b ∧ a ≠ c ∧ b ≠ c
Used simplifier rules: ⊦ m < n → n ≠ 0; (s)%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic%fle: ⊦ m < n ∧ n ≤ n0 → m < n0; (forward) from specification nat% ⊦ m < n ↔ ¬ n ≤ m; (ss)