| fits(r, sks, st), unchanged(str, r, st, st0) ⊦ fits(r, sks, st0), st[r -- sks] = st0[r -- sks], junkref(str, r, st), junkref(str, r, st0) |
⊦ ¬ junkref(str, r, st) ∧ fits(r, sks, st) ∧ unchanged(str, r, st, st0) → fits(r, sks, st0)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (str, r, st, sks, st0)]]