Definition st_ok (st : STt) (interp: positive -> COINCpoint) :=
  forall t, STmem t st = true -> app wd (interp_CP t interp).

Lemma test_coinc_ok : forall ss st interp cp, ss_ok ss interp -> st_ok st interp -> test_coinc ss st cp = true -> app coinc (interp_CP cp interp).