intros hyps F p g e; apply project_In.
apply get_In with p;assumption.
Qed.
Arguments project [hyps] F [p g] _.
Inductive proof:Set :=
Ax : positive -> proof
| I_Arrow : proof -> proof
| E_Arrow : positive -> positive -> proof -> proof
| D_Arrow : positive -> proof -> proof -> proof
| E_False : positive -> proof
| I_And: proof -> proof -> proof
| E_And: positive -> proof -> proof
| D_And: positive -> proof -> proof
| I_Or_l: proof -> proof
| I_Or_r: proof -> proof
| E_Or: positive -> proof -> proof -> proof
| D_Or: positive -> proof -> proof
| Cut: form -> proof -> proof -> proof.
Notation "hyps \ A" := (push A hyps) (at level 72,left associativity).
Fixpoint check_proof (hyps:ctx) (gl:form) (P:proof) {struct P}: bool :=
match P with
Ax i =>
match get i hyps with
PSome F => form_eq F gl
| _ => false
end
| I_Arrow p =>
match gl with
A  =>> B  => check_proof (hyps \ A) B p
| _ => false
end
| E_Arrow i j p =>
match get i hyps,get j hyps with
PSome A,PSome (B =>>C) =>
form_eq A B && check_proof (hyps \ C) (gl) p
| _,_ => false
end
| D_Arrow i p1 p2 =>
match get i hyps with
PSome  ((A =>>B)=>>C) =>
(check_proof ( hyps \ B =>> C \ A) B p1) && (check_proof (hyps \ C) gl p2)
| _ => false
end
| E_False i =>
match get i hyps with
PSome # => true
| _ => false
end
| I_And p1 p2 =>
match gl with
A //\\ B =>
check_proof hyps A p1 && check_proof hyps B p2
| _ => false
end
| E_And i p =>
match get i hyps with
PSome  (A //\\ B) => check_proof (hyps \ A \ B) gl p
| _=> false
end
| D_And i p =>
match get i hyps with
PSome  (A //\\ B =>> C) => check_proof (hyps \ A=>>B=>>C) gl p
| _=> false
end
| I_Or_l p =>
match gl with
(A \\// B) => check_proof hyps A p
| _ => false
end
| I_Or_r p =>
match gl with
(A \\// B) => check_proof hyps B p
| _ => false
end
| E_Or i p1 p2 =>
match get i hyps with
PSome (A \\// B) =>
check_proof (hyps \ A) gl p1 && check_proof (hyps \ B) gl p2
| _=> false
end
| D_Or i p =>
match get i hyps with
PSome  (A \\// B =>> C) =>
(check_proof (hyps \ A=>>C \ B=>>C) gl p)
| _=> false
end
| Cut A p1 p2 =>
check_proof hyps A p1 && check_proof (hyps \ A) gl p2
end.

(* Specifications: *)
Theorem interp_proof:
forall p hyps F gl,
check_proof hyps gl p = true -> interp_ctx hyps F [[gl]].