| st[a, d][b, d0] = st[b, d0] ⊦ a = b, a ∈ st ∧ st[a] = d |
⊦ st1 = st2 ↔ (∀ a. (a ∈ st1 ↔ a ∈ st2) ∧ st1[a] = st2[a])
∀ a0. (a0 ∈ st[a, d][b, d0] ↔ a0 ∈ st[b, d0]) ∧ st[a, d][b, d0][a0] = st[b, d0][a0] ⊦ a = b, a ∈ st ∧ st[a] = d
Used terms: st[b, d0], st[a, d][b, d0]