| ⊦ validrefkeynotnull(str, rk, ty, st) → validrefkeynotnull(str, rk, ty, st0 ∪ st) |
⊦ validrefkeynotnull(str, rk, ty, st) ∧ (∃ st0. st1 = st0 ∪ st) → validrefkeynotnull(str, rk, ty, st1)
validrefkeynotnull(str, rk, ty, st) ∧ (∃ st2. st0 ∪ st = st2 ∪ st) → validrefkeynotnull(str, rk, ty, st0 ∪ st) ⊦ validrefkeynotnull(str, rk, ty, st) → validrefkeynotnull(str, rk, ty, st0 ∪ st)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (str, rk, ty, st, st0 ∪ st)]]