| st .min = r0 -- sk, r -- sk0 ∈ st, r ∈ st ⊦ r = r0, r -- sk0 ∈ st .butmin |
⊦ rk ∈ st .butmin ↔ st ≠ ∅ ∧ rk ∈ st ∧ rk ≠ st .min
⊦ ¬ r ∈ ∅
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ st .min = rk ∧ st ≠ ∅ → rk ∈ st], [CSIMPSEQ : ⊦ r -- sk = r0 -- sk0 ↔ r = r0 ∧ sk = sk0])], [EXTRATERMS : (st, r -- sk0)]]