| validref(str, r, st[r -- _type] .type, st), st ⊆ st0, validrefs(str, r ' + refs, ty, st0), ∀ st, st0, ty, r, str, refs0. # refs0 < # refs → (validrefs(str, r ' + refs0, ty, st0) ∧ st ⊆ st0 ∧ validref(str, r, st[r -- _type] .type, st) → validrefs(str, r ' + refs0, ty, st)) ⊦ validrefs(str, r ' + refs, ty, st) |
⊦ validref(str, r, st[r -- _type] .type, st) ↔ ¬ junkref(str, r, st)
¬ junkref(str, r, st), st ⊆ st0, validrefs(str, r ' + refs, ty, st0), ∀ st, st0, ty, r, str, refs0. # refs0 < # refs → (validrefs(str, r ' + refs0, ty, st0) ∧ st ⊆ st0 ∧ validref(str, r, st[r -- _type] .type, st) → validrefs(str, r ' + refs0, ty, st)) ⊦ validrefs(str, r ' + refs, ty, st)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, r, str)]]