Definition CSharpMin_halted (q : CSharpMin_core): option val :=
    match q with
       CSharpMin_Returnstate v Kstop => Some v
     | _ => None
    end.

Lemma CSharpMin_at_external_halted_excl : forall q, CSharpMin_at_external q = None \/ CSharpMin_halted q = None.