| # s0 + #(s1 ++ a) < #(s0 ∩ (s1 ++ a)), ∀ s0. ¬ # s0 + # s1 < #(s0 ∩ s1) ⊦ |
⊦ a ∈ s → s ++ a = s
# s0 + #(s1 ++ a) < #(s0 ∩ (s1 ++ a)), ∀ s0. ¬ # s0 + # s1 < #(s0 ∩ s1) ⊦ a ∈ s1
# s0 + # s1 < #(s0 ∩ s1), a ∈ s1, ∀ s0. ¬ # s0 + # s1 < #(s0 ∩ s1) ⊦
Used terms: a, s1