| a ∈ st[a, d] → a ∈ st0 ∧ st[a, d][a] = st0[a], ∀ a0. a0 ∈ st[a, d] → a0 ∈ st0 ∧ st[a, d][a0] = st0[a0] ⊦ (a0 ∈ st -- a → a0 ∈ st0 ∧ st[a0] = st0[a0]) ∧ a ∈ st0 ∧ st0[a] = d |
a0 ∈ st, a ∈ st0, a ∈ st[a, st0[a]], ∀ a0. a0 ∈ st[a, st0[a]] → a0 ∈ st0 ∧ st[a, st0[a]][a0] = st0[a0] ⊦ a0 = a, a0 ∈ st0 ∧ st[a0] = st0[a0]
Used simplifier rules: At-same: ⊦ st[a, d][a] = d;%In-insert: ⊦ a ∈ st[b, d] ↔ a = b ∨ a ∈ st;%Del-in: ⊦ a ∈ st -- b ↔ a ≠ b ∧ a ∈ st;