a ∈ st0[a0, d], ∀ a. a ∈ st0 → (∃ st1. ¬ a ∈ st1 ∧ st0 = st1[a, st0[a]]) ⊦ ∃ st1. ¬ a ∈ st1 ∧ st0[a0, d] = st1[a, st0[a0, d][a]]
Used simplifier rules: gen: ⊦ ;%In-empty: ⊦ ¬ a ∈ ∅;