| ∀ str, r, ty, class, st. validref(str, r, ty, addclass(class, fis0, st)) ↔ validref(str, r, ty, st) ⊦ validref(str, r, ty, addclass(class, fv ' + fis0, st)) ↔ validref(str, r, ty, st) |
⊦ is_fskey(fv .1) ∧ fv .1 .fs .class ≠ class → addclass(class, fv ' + fis, st) = addclass(class, fis, st)
¬ (is_fskey(fv .1) ∧ fv .1 .fs .class ≠ class), ∀ str, r, ty, class, st. validref(str, r, ty, addclass(class, fis0, st)) ↔ validref(str, r, ty, st) ⊦ validref(str, r, ty, addclass(class, fv ' + fis0, st)) ↔ validref(str, r, ty, st)
is_fskey(fv .1) ∧ fv .1 .fs .class ≠ class, ∀ str, r, ty, class, st. validref(str, r, ty, addclass(class, fis0, st)) ↔ validref(str, r, ty, st) ⊦ validref(str, r, ty, addclass(class, fis0, st)) ↔ validref(str, r, ty, st)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, fis0, fv, class)]]