| s0 ++ a = ∅ ++ a0 ++ b ⊦ 1 = # s0, a0 = b, s0 = ∅ ++ b, a ∈ s0, ∃ a. s0 = ∅ ++ a |
s0 ++ a = ∅ ++ a0 ++ b ⊦ 1 = # s0, a0 = b, s0 = ∅ ++ b, a ∈ s0, b ∈ ∅, ∃ a. s0 = ∅ ++ a
Used simplifier rules: eq: ⊦ a ∈ s → s ++ a = s;%In-empty: ⊦ ¬ a ∈ ∅; Used formulas: b ∈ ∅