| validrefs(str, r1 ' + refs0, ty, st), r0 ∈ refs0, ∀ r. r = r1 ∨ r ∈ refs0 → unchangedNorec(r, st, st0) ⊦ r0 = r1, path∃(str, r1, r0, st0) |
⊦ r ∈ refs ↔ (∃ refs0, refs1. refs = refs0 + (r + refs1))
validrefs(str, r1 ' + refs0, ty, st), ∃ refs2, refs1. refs0 = refs2 + (r0 + refs1), ∀ r. r = r1 ∨ r ∈ refs0 → unchangedNorec(r, st, st0) ⊦ r0 = r1, path∃(str, r1, r0, st0)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (refs0, r0)]]