| c ∈ s ⊦ a ∈ s, c = a, c = a0, c = b, s ⊆ s ++ a ++ a0 ++ b ++ c |
c ∈ s ⊦ a0 ∈ s ++ a, a ∈ s, c = a, c = a0, c = b, s ⊆ s ++ a ++ a0 ++ b ++ c
Used simplifier rules: rax: ⊦ a ∈ s ++ b ↔ ¬ ¬(a = b ∨ a ∈ s);%add-01: ⊦ s ++ a ++ a = s ++ a;%subset-insert: ⊦ s ⊆ s ++ a ++ b ++ c;%ins-two: ⊦ a ∈ s → s ++ b ++ a = s ++ b; Used formulas: a0 ∈ s ++ a