| ⊦ ¬ b ∈ s ∧ a ≠ b → (s ++ b) -- a = (s -- a) ++ b |
a0 = b ∨ a0 ≠ a ∧ a0 ∈ s ⊦ a = b, b ∈ s, a0 ≠ a ∧ (a0 = b ∨ a0 ∈ s)
Used simplifier rules: del-rax: ⊦ a ∈ s -- b ↔ ¬ ¬(a ≠ b ∧ a ∈ s);%Delete: ⊦ a ∈ s -- b ↔ a ≠ b ∧ a ∈ s;%rax: ⊦ a ∈ s ++ b ↔ ¬ ¬(a = b ∨ a ∈ s); from specification set-basic%Extension: ⊦ s1 = s2 ↔ (∀ a. a ∈ s1 ↔ a ∈ s2); from specification set-basic