| a ∈ st0, st1 -- a ⊆ st0 -- a, a ∈ st1, # st0 < # st1, ∀ st0. # st0 < # st1 → ¬ st1 ⊆ st0 ⊦ st1[a] = st0[a], st1 = ∅, st1[a, st0[a]] = ∅, st1 ⊆ st0[a, st1[a]] |
⊦ st ⊆ st0[a, d] ↔ st ⊆ st0 ∧ ¬ a ∈ st ∨ a × d ∈ st ∧ st -- a ⊆ st0 -- a
Used simplifier rules: subset-elem-eq-01: ⊦ b ∈ st ∧ st[b] ≠ st1[b] → ¬ st ⊆ st1;%in-pair: ⊦ a × d ∈ st ↔ ¬ ¬(a ∈ st ∧ st[a] = d); Used terms: st1[a], a, st0, st1