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