| ∀ str, ty, st, r. validrefs(str, acc, ty, st) → r ∈ acc ∨ validrefs(str, acc, ty, st -- r), validrefs(str, r0 + acc, ty, st) ⊦ r ∈ r0 + acc, validrefs(str, r0 + acc, ty, st -- r) |
validrefs(str, r0 ' + acc, ty, st), ∀ str, ty, st, r. validrefs(str, acc, ty, st) → r ∈ acc ∨ validrefs(str, acc, ty, st -- r) ⊦ r = r0, r ∈ acc, validrefs(str, r0 ' + acc, ty, st -- r)
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ (refs + refs0) + refs1 = refs + refs0 + refs1], [CSIMPSEQ : ⊦ ¬ r ∈ r0 ' + refs ↔ r ≠ r0 ∧ ¬ r ∈ refs], [CSIMPSEQ : ⊦ r + refs = r ' + refs])]]