| c ∈ s ⊦ b ∈ s ++ a ++ a0, c = b, a0 = a, a ∈ s, s ⊆ s ++ a ++ a0 ++ b ++ c, a0 ∈ s |
c ∈ s ⊦ a0 = a, b = a0, b = a, a ∈ s, s ⊆ s ++ a ++ a0 ++ b ++ c, a0 ∈ s, b ∈ s
Used simplifier rules: add: ⊦ ¬ a ∈ s ++ b ↔ a ≠ b ∧ ¬ a ∈ s;%rax: ⊦ a ∈ s ++ b ↔ ¬ ¬(a = b ∨ a ∈ s);