Axiom
  typest_writing :
    forall t t' : type,
    typest t t' -> capst (getcap t') Write -> typest (getobj t') (getobj t).Axiom
  typest_reading :
    forall t t' : type,
    typest t t' -> capst (getcap t') Read -> typest (getobj t) (getobj t').Axiom
  typest_tail :
    forall t t' : type, typest t t' -> capst (getcap t) (getcap t').

Theorem est_refl : forall G : env, envst G G.