From: Claudio Sacerdoti Coen <claudio.sacerdoticoen@unibo.it>
Date: Fri, 15 Jun 2018 14:36:37 +0000 (+0200)
Subject: Embarassing bug in eta_eq fixed
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=b8b634b6e8907bb7c5e1a228ec173fab2b7b6546;p=fireball-separation.git

Embarassing bug in eta_eq fixed
---

diff --git a/ocaml/simple.ml b/ocaml/simple.ml
index aa91996..bfb5ebd 100644
--- a/ocaml/simple.ml
+++ b/ocaml/simple.ml
@@ -13,31 +13,6 @@ type t =
  | L of t
 ;;
 
-let delta = L(A(V 0, V 0));;
-
-let eta_eq' =
- let rec aux l1 l2 t1 t2 = match t1, t2 with
-  | L t1, L t2 -> aux l1 l2 t1 t2
-  | L t1, t2 -> aux l1 (l2+1) t1 t2
-  | t1, L t2 -> aux (l1+1) l2 t1 t2
-  | V a, V b -> a + l1 = b + l2
-  | A(t1,t2), A(u1,u2) -> aux l1 l2 t1 u1 && aux l1 l2 t2 u2
-  | _, _ -> false
- in aux ;;
-let eta_eq = eta_eq' 0 0;;
-
-(* is arg1 eta-subterm of arg2 ? *)
-let eta_subterm u =
- let rec aux lev t = eta_eq' lev 0 u t || match t with
- | L t -> aux (lev+1) t
- | A(t1, t2) -> aux lev t1 || aux lev t2
- | _ -> false
- in aux 0
-;;
-
-(* does NOT lift the argument *)
-let mk_lams = fold_nat (fun x _ -> L x) ;;
-
 let string_of_t =
   let string_of_bvar =
    let bound_vars = ["x"; "y"; "z"; "w"; "q"] in
@@ -57,6 +32,12 @@ let string_of_t =
   in string_of_term_no_pars 0
 ;;
 
+
+let delta = L(A(V 0, V 0));;
+
+(* does NOT lift the argument *)
+let mk_lams = fold_nat (fun x _ -> L x) ;;
+
 type problem = {
    orig_freshno: int
  ; freshno : int
@@ -134,6 +115,25 @@ and lift n =
 ;;
 let subst = subst 0 false;;
 
+let eta_eq =
+ let rec aux t1 t2 = match t1, t2 with
+  | L t1, L t2 -> aux t1 t2
+  | L t1, t2 -> aux t1 (A(lift 1 t2,V 0))
+  | t1, L t2 -> aux (A(lift 1 t1,V 0)) t2
+  | V a, V b -> a = b
+  | A(t1,t2), A(u1,u2) -> aux t1 u1 && aux t2 u2
+  | _, _ -> false
+ in aux ;;
+
+(* is arg1 eta-subterm of arg2 ? *)
+let eta_subterm u =
+ let rec aux lev t = eta_eq u (lift lev t) || match t with
+ | L t -> aux (lev+1) t
+ | A(t1, t2) -> aux lev t1 || aux lev t2
+ | _ -> false
+ in aux 0
+;;
+
 let subst_in_problem ((v, t) as sub) p =
 print_endline ("-- SUBST " ^ string_of_t (V v) ^ " |-> " ^ string_of_t t);
  let sigma = sub::p.sigma in