| ps=(r, st, r1, st1) ⊦ ps=(r1, st1, r, st), cyclic(str, r, st), cyclic(str, r1, st1), junkref(str, r, st), junkref(str, r1, st1) |
⊦ ¬ cyclic(str, r, st) ∧ ¬ cyclic(str, r1, st1) ∧ ¬ junkref(str, r, st) ∧ ¬ junkref(str, r1, st1) → (ps=(r, st, r1, st1) → ps=(r1, st1, r, st))
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (str, r, st, r1, st1)]]