| ⊦ ¬ junkref(str, r, st) ∧ st ⊆ st1 → ¬ junkref(str, r, st1) |
⊦ junkref(str, r, st) ↔ (∃ refs. refs ≠ [] ∧ refs .first = r ∧ junkrefs(str, refs, st[r -- _type] .type, st))
⊦ ¬ (∃ refs. refs ≠ [] ∧ refs .first = r ∧ junkrefs(str, refs, st[r -- _type] .type, st)) ∧ st ⊆ st1 → ¬ junkref(str, r, st1)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, r, str)]]