| validrefs(str, r ' + refs, ty, st), r0 ∈ refs, validrefs(str, r ' + refs, st[r -- _type] .type, st) ⊦ ∃ refs. refs ≠ [] ∧ refs .first = r ∧ refs .last = r0 ∧ validrefs(str, refs, st[r -- _type] .type, st) |
validrefs(str, r ' + refs, ty, st), r0 ∈ refs, validrefs(str, r ' + refs, st[r -- _type] .type, st) ⊦ ∃ refs0. refs0 ≠ [] ∧ refs0 .first = r ∧ refs0 .last = r0 ∧ validrefs(str, refs0, st[refs0 .first -- _type] .type, st)
[[CONCRETESIMPRULES : ()]]