| ⊦ validrefs(str, refs, ty, st) ∧ validrefs(str, refs0, ty0, st) ∧ refs .last = refs0 .first ∧ refs ≠ [] ∧ refs0 ≠ [] → validrefs(str, refs + refs0 .rest, ty, st) |
refs .last = refs0 .first, validrefs(str, refs0, ty0, st), validrefs(str, refs, ty, st) ⊦ refs = [], refs0 = [], validrefs(str, refs + refs0 .rest, ty, st)
[[CONCRETESIMPRULES : ()]]