| refs0 = r + refs1, refs .last = r, validrefs(str, refs0, ty0, st), validrefs(str, refs, ty, st) ⊦ refs = [], refs0 = [], validrefs(str, refs + refs1, ty, st) |
validrefs(str, refs, ty, st), validrefs(str, refs .last ' + refs1, ty0, st) ⊦ refs = [], validrefs(str, refs + refs1, ty, st)
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ (refs + refs0) + refs1 = refs + refs0 + refs1], [CSIMPSEQ : ⊦ r ' + refs ≠ []], [CSIMPSEQ : ⊦ r + refs = r ' + refs])]]