| validrefs(str, refs, st[refs .first -- _type] .type, st) ⊦ refs .first = refs .last, refs = [], dups(refs), ∃ refs0. refs0 ≠ [] ∧ refs0 .first = refs .first ∧ refs0 .last = refs .last ∧ validrefs(str, refs0, st[refs0 .first -- _type] .type, st) |
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (refs)]]