⊦ st1 = st2 ↔ (∀ a. (a ∈ st1 ↔ a ∈ st2) ∧ st1[a] = st2[a])
∀ a. (a ∈ st1 ↔ a ∈ st2) ∧ (a ∈ st1 → st1[a] = st2[a]) ⊦ ∀ a. (a ∈ st1 ↔ a ∈ st2) ∧ st1[a] = st2[a]
Used terms: st2, st1