| st0 = st[a, st0[a]], a ∈ st0, ∀ a. a ∈ st0 → (∃ st1. ¬ a ∈ st1 ∧ st0 = st1[a, st0[a]]) ⊦ a = a0, ∀ a1. (a1 ∈ st0[a0, d] ↔ a1 ∈ st[a0, d][a, st0[a]]) ∧ st0[a0, d][a1] = st[a0, d][a, st0[a]][a1], a ∈ st, ∃ st1. ¬ a ∈ st1 ∧ st0[a0, d] = st1[a, st0[a]] |
st0 = st[a, st0[a]], a ∈ st0, ∀ a. a ∈ st0 → (∃ st1. ¬ a ∈ st1 ∧ st0 = st1[a, st0[a]]) ⊦ a = a0, a ∈ st, (a1 ∈ st0[a0, d] ↔ a1 ∈ st[a0, d][a, st0[a]]) ∧ st0[a0, d][a1] = st[a0, d][a, st0[a]][a1], ∃ st1. ¬ a ∈ st1 ∧ st0[a0, d] = st1[a, st0[a]]