b ∈ st ⊦ b = a, st[a, d][b] = st[b], a ∈ st
Used simplifier rules: At-same: ⊦ st[a, d][a] = d;%notmemlookup: ⊦ ¬ a ∈ st → st[a] = (∅)[a]; Used formulas: b = a