| validrefs(str, refs, ty, st) ⊦ refs = [], ∃ sks. fits(refs .first, sks, st) ∧ st[refs .first -- sks] .refval = refs .last |
refs = r + refs0, validrefs(str, refs, ty, st) ⊦ refs = [], ∃ sks. fits(r, sks, st) ∧ st[r -- sks] .refval = refs .last
[[CONCRETESIMPRULES : ([CSIMPELIM : refs ≠ [] ⊦ r = refs .first ∧ refs0 = refs .rest ↔ refs = r + refs0])], [EXTRATERMS : (refs, r, refs0)]]