| st ⊆ st0, cyclic(str, r, st) ⊦ junkref(str, r, st), cyclic(str, r, st0) |
⊦ cyclic(str, r, st) ↔ (∃ refs. dups(refs) ∧ refs .first = r ∧ validrefs(str, refs, st[r -- _type] .type, st))
st ⊆ st0, ∃ refs. dups(refs) ∧ refs .first = r ∧ validrefs(str, refs, st[r -- _type] .type, st) ⊦ junkref(str, r, st), cyclic(str, r, st0)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, r, str)]]