Embarassing bug in eta_eq fixed

[fireball-separation.git] / ocaml / simple.ml

diff --git a/ocaml/simple.ml b/ocaml/simple.ml
index 154992dd3f056dad04a1334eff68b75b7be211b7..bfb5ebd71c50d076f070c432aec10451d12cc420 100644 (file)
--- a/ocaml/simple.ml
+++ b/ocaml/simple.ml
@@ -13,31 +13,6 @@ type t =
  | L of t\r
 ;;\r
 \r
-let delta = L(A(V 0, V 0));;\r
-\r
-let eta_eq' =\r
- let rec aux l1 l2 t1 t2 = match t1, t2 with\r
-  | L t1, L t2 -> aux l1 l2 t1 t2\r
-  | L t1, t2 -> aux l1 (l2+1) t1 t2\r
-  | t1, L t2 -> aux (l1+1) l2 t1 t2\r
-  | V a, V b -> a + l1 = b + l2\r
-  | A(t1,t2), A(u1,u2) -> aux l1 l2 t1 u1 && aux l1 l2 t2 u2\r
-  | _, _ -> false\r
- in aux ;;\r
-let eta_eq = eta_eq' 0 0;;\r
-\r
-(* is arg1 eta-subterm of arg2 ? *)\r
-let eta_subterm u =\r
- let rec aux lev t = eta_eq' lev 0 u t || match t with\r
- | L t -> aux (lev+1) t\r
- | A(t1, t2) -> aux lev t1 || aux lev t2\r
- | _ -> false\r
- in aux 0\r
-;;\r
-\r
-(* does NOT lift the argument *)\r
-let mk_lams = fold_nat (fun x _ -> L x) ;;\r
-\r
 let string_of_t =\r
   let string_of_bvar =\r
    let bound_vars = ["x"; "y"; "z"; "w"; "q"] in\r
@@ -57,6 +32,12 @@ let string_of_t =
   in string_of_term_no_pars 0\r
 ;;\r
 \r
+\r
+let delta = L(A(V 0, V 0));;\r
+\r
+(* does NOT lift the argument *)\r
+let mk_lams = fold_nat (fun x _ -> L x) ;;\r
+\r
 type problem = {\r
    orig_freshno: int\r
  ; freshno : int\r
@@ -115,7 +96,7 @@ let rec no_leading_lambdas v n = function
 let rec subst level delift sub =\r
  function\r
  | V v -> if v = level + fst sub then lift level (snd sub) else V (if delift && v > level then v-1 else v)\r
- | L t -> let t = subst (level + 1) delift sub t in if t = B then B else L t\r
+ | L t -> L (subst (level + 1) delift sub t)\r
  | A (t1,t2) ->\r
   let t1 = subst level delift sub t1 in\r
   let t2 = subst level delift sub t2 in\r
@@ -134,6 +115,25 @@ and lift n =
 ;;\r
 let subst = subst 0 false;;\r
 \r
+let eta_eq =\r
+ let rec aux t1 t2 = match t1, t2 with\r
+  | L t1, L t2 -> aux t1 t2\r
+  | L t1, t2 -> aux t1 (A(lift 1 t2,V 0))\r
+  | t1, L t2 -> aux (A(lift 1 t1,V 0)) t2\r
+  | V a, V b -> a = b\r
+  | A(t1,t2), A(u1,u2) -> aux t1 u1 && aux t2 u2\r
+  | _, _ -> false\r
+ in aux ;;\r
+\r
+(* is arg1 eta-subterm of arg2 ? *)\r
+let eta_subterm u =\r
+ let rec aux lev t = eta_eq u (lift lev t) || match t with\r
+ | L t -> aux (lev+1) t\r
+ | A(t1, t2) -> aux lev t1 || aux lev t2\r
+ | _ -> false\r
+ in aux 0\r
+;;\r
+\r
 let subst_in_problem ((v, t) as sub) p =\r
 print_endline ("-- SUBST " ^ string_of_t (V v) ^ " |-> " ^ string_of_t t);\r
  let sigma = sub::p.sigma in\r
@@ -206,12 +206,17 @@ let inert_cut_at n t =
 let find_eta_difference p t argsno =\r
  let t = inert_cut_at argsno t in\r
  let rec aux t u k = match t, u with\r
- | V _, V _ -> problem_fail p "no eta difference found (div subterm of conv?)"\r
+ | V _, V _ -> None\r
  | A(t1,t2), A(u1,u2) ->\r
-    if not (eta_eq t2 u2) then (k-1)\r
-    else aux t1 u1 (k-1)\r
+    (match aux t1 u1 (k-1) with\r
+    | None ->\r
+      if not (eta_eq t2 u2) then Some (k-1)\r
+      else None\r
+    | Some j -> Some j)\r
  | _, _ -> assert false\r
- in aux p.div t argsno\r
+ in match aux p.div t argsno with\r
+ | None -> problem_fail p "no eta difference found (div subterm of conv?)"\r
+ | Some j -> j\r
 ;;\r
 \r
 let compute_max_lambdas_at hd_var j =\r
@@ -269,8 +274,8 @@ print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (of:" ^ string_of_int n ^ ")")
     let p, v = freshvar p in\r
     p, A(t, V (v + k + 1))\r
   ) (p, V 0) n in\r
- let t = (* apply unused bound variables V_{k-1}..V_1 *)\r
-  fold_nat (fun t m -> A(t, V (k-m+1))) t k in\r
+ let t = (* apply bound variables V_k..V_0 *)\r
+  fold_nat (fun t m -> A(t, V (k-m+1))) t (k+1) in\r
  let t = mk_lams t (k+1) in (* make leading lambdas *)\r
  let subst = var, t in\r
  let p = subst_in_problem subst p in\r