| junkref(str, (r ' + refs0) .last, st), validrefs(str, r ' + refs0, st[r -- _type] .type, st) ⊦ refs0 = [], junkref(str, r, st) |
validrefs(str, r ' + refs0, st[r -- _type] .type, st), junkref(str, refs0 .last, st) ⊦ refs0 = [], junkref(str, r, st)
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ (refs + refs0) + refs1 = refs + refs0 + refs1], [CSIMPSEQ : ⊦ refs ≠ [] → (r ' + refs) .last = refs .last])]]