| i < 0, validrefs(str, r ' + refs1, st[r -- _type] .type, st) ⊦ validrefs(str, r ' + refs1, st[r -- _type] .type, st[r0 -- i ', val]) |
⊦ i < 0 → (validrefs(str, refs, ty, st[r -- i ', val]) ↔ validrefs(str, refs, ty, st))
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (val, i, r0, st, st[r -- _type] .type, r ' + refs1, str)]]