X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=ocaml%2Fsimple.ml;h=44b9aa2a871d74619fdcbe88599580ce4c7b2d70;hb=484254ec5f3e94aa86ffdc2bf7c07c46e42be8d7;hp=a63314959984a88c3407ec8d20f89a60a9c1efd1;hpb=69f6ab5b05bcbeb0ced857415c7c48460ae0bdcb;p=fireball-separation.git

diff --git a/ocaml/simple.ml b/ocaml/simple.ml
index a633149..44b9aa2 100644
--- a/ocaml/simple.ml
+++ b/ocaml/simple.ml
@@ -17,8 +17,15 @@ type t =
 
 let delta = L(A(V 0, V 0));;
 
+let rec is_stuck = function
+ | C -> true
+ | A(t,_) -> is_stuck t
+ | _ -> false
+;;
+
 let eta_eq' =
  let rec aux l1 l2 t1 t2 = match t1, t2 with
+  | _, _ when is_stuck t1 || is_stuck t2 -> true
   | 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
@@ -30,11 +37,11 @@ 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
+ let rec aux lev t = if t = C then false else (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
+ | _ -> false) in
+ aux 0
 ;;
 
 (* does NOT lift the argument *)
@@ -93,6 +100,8 @@ let freshvar ({freshno} as p) =
  {p with freshno=freshno+1}, freshno+1
 ;;
 
+(* CSC: rename? is an applied C an inert?
+   is_inert and get_inert work inconsistently *)
 let rec is_inert =
  function
  | A(t,_) -> is_inert t
@@ -101,17 +110,36 @@ let rec is_inert =
  | L _ | B -> false
 ;;
 
+let rec is_constant =
+ function
+    C -> true
+  | V _ -> false
+  | B -> assert false
+  | A(t,_)
+  | L t -> is_constant t
+;;
+
 let rec get_inert = function
- | V n -> (n,0)
+ | V _ | C as t -> (t,0)
  | A(t, _) -> let hd,args = get_inert t in hd,args+1
  | _ -> assert false
 ;;
 
+let args_of_inert =
+ let rec aux acc =
+  function
+   | V _ | C -> acc
+   | A(t, a) -> aux (a::acc) t
+   | _ -> assert false
+ in
+  aux []
+;;
+
 (* precomputes the number of leading lambdas in a term,
    after replacing _v_ w/ a term starting with n lambdas *)
 let rec no_leading_lambdas v n = function
  | L t -> 1 + no_leading_lambdas (v+1) n t
- | A _ as t -> let v', m = get_inert t in if v = v' then max 0 (n - m) else 0
+ | A _ as t -> let v', m = get_inert t in if V v = v' then max 0 (n - m) else 0
  | V v' -> if v = v' then n else 0
  | B | C -> 0
 ;;
@@ -150,19 +178,16 @@ print_endline ("-- SUBST " ^ string_of_t (V v) ^ " |-> " ^ string_of_t t);
   sigma=sub::p.sigma}
 ;;
 
-let get_subterm_with_head_and_args hd_var n_args =
- let rec aux lev = function
- | C | V _ | B -> None
- | L t -> aux (lev+1) t
+let get_subterms_with_head hd_var =
+ let rec aux lev inert_done = function
+ | C | V _ | B -> []
+ | L t -> aux (lev+1) false t
  | A(t1,t2) as t ->
    let hd_var', n_args' = get_inert t1 in
-   if hd_var' = hd_var + lev && n_args <= 1 + n_args'
-    (* the `+1` above is because of t2 *)
-    then Some (lift ~-lev t)
-    else match aux lev t2 with
-    | None -> aux lev t1
-    | Some _ as res -> res
- in aux 0
+   if not inert_done && hd_var' = V (hd_var + lev)
+    then lift ~-lev t :: aux lev true t1 @ aux lev false t2
+    else aux lev true t1 @ aux lev false t2
+ in aux 0 false
 ;;
 
 let rec purify = function
@@ -197,8 +222,6 @@ let sanity p =
 ;;
 
 (* drops the arguments of t after the n-th *)
-(* FIXME! E' usato in modo improprio contando sul fatto
-   errato che ritorna un inerte lungo esattamente n *)
 let inert_cut_at n t =
  let rec aux t =
   match t with
@@ -212,26 +235,26 @@ let inert_cut_at n t =
 ;;
 
 (* return the index of the first argument with a difference
-   (the first argument is 0)
-   precondition: p.div and t have n+1 arguments
-   *)
-let find_eta_difference p t argsno =
- let t = inert_cut_at argsno t in
- let rec aux t u k = match t, u with
- | V _, V _ -> problem_fail p "no eta difference found (div subterm of conv?)"
- | A(t1,t2), A(u1,u2) ->
-    if not (eta_eq t2 u2) then (k-1)
-    else aux t1 u1 (k-1)
- | _, _ -> assert false
- in aux p.div t argsno
+   (the first argument is 0) *)
+let find_eta_difference p t =
+ let divargs = args_of_inert p.div in
+ let conargs = args_of_inert t in
+ let rec aux k divargs conargs =
+  match divargs,conargs with
+     [],_ -> []
+   | _::_,[] -> [k]
+   | t1::divargs,t2::conargs ->
+      (if not (eta_eq t1 t2) then [k] else []) @ aux (k+1) divargs conargs
+ in
+  aux 0 divargs conargs
 ;;
 
 let compute_max_lambdas_at hd_var j =
  let rec aux hd = function
  | A(t1,t2) ->
-    (if get_inert t1 = (hd, j)
+    (if get_inert t1 = (V hd, j)
       then max ( (*FIXME*)
-       if is_inert t2 && let hd', j' = get_inert t2 in hd' = hd
+       if is_inert t2 && let hd', j' = get_inert t2 in hd' = V hd
         then let hd', j' = get_inert t2 in j - j'
         else no_leading_lambdas hd_var j t2)
       else id) (max (aux hd t1) (aux hd t2))
@@ -243,6 +266,18 @@ let compute_max_lambdas_at hd_var j =
 
 let print_cmd s1 s2 = print_endline (">> " ^ s1 ^ " " ^ s2);;
 
+(* returns Some i if i is the smallest integer s.t. p holds for the i-th
+   element of the list in input *)
+let smallest_such_that p =
+ let rec aux i =
+  function
+     [] -> None
+   | hd::_ when (print_endline (string_of_t hd) ; p hd) -> Some i
+   | _::tl -> aux (i+1) tl
+ in
+  aux 0
+;;
+
 (* eat the arguments of the divergent and explode.
  It does NOT perform any check, may fail if done unsafely *)
 let eat p =
@@ -255,17 +290,21 @@ print_cmd "EAT" "";
  let p =
   match phase with
   | `One ->
+      let i =
+       match smallest_such_that (fun x -> not (is_constant x)) (args_of_inert p.div) with
+          Some i -> i
+        | None -> assert false (*CSC: backtrack? *) in
       let n = 1 + max
-       (compute_max_lambdas_at var (k-1) p.div)
-       (compute_max_lambdas_at var (k-1) p.conv) in
+       (compute_max_lambdas_at var (k-i-1) p.div)
+       (compute_max_lambdas_at var (k-i-1) p.conv) in
       (* apply fresh vars *)
       let p, t = fold_nat (fun (p, t) _ ->
         let p, v = freshvar p in
         p, A(t, V (v + k))
-      ) (p, V 0) n in
+      ) (p, V (k-1-i)) n in
       let p = {p with phase=`Two} in
       let t = A(t, delta) in
-      let t = fold_nat (fun t m -> A(t, V (k-m))) t (k-1) in
+      let t = fold_nat (fun t m -> if k-m = i then t else  A(t, V (k-m))) t k in
       let subst = var, mk_lams t k in
       let p = subst_in_problem subst p in
       let _, args = get_inert p.div in
@@ -278,8 +317,11 @@ print_cmd "EAT" "";
 
 (* step on the head of div, on the k-th argument, with n fresh vars *)
 let step k n p =
- let var, _ = get_inert p.div in
-print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (of:" ^ string_of_int n ^ ")");
+ let hd, _ = get_inert p.div in
+ match hd with
+ | C | L _ | B | A _  -> assert false
+ | V var ->
+print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (on " ^ string_of_int (k+1) ^ "th)");
  let p, t = (* apply fresh vars *)
   fold_nat (fun (p, t) _ ->
     let p, v = freshvar p in
@@ -293,24 +335,45 @@ print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (of:" ^ string_of_int n ^ ")")
  sanity p
 ;;
 
-let rec auto p =
- let hd_var, n_args = get_inert p.div in
- match get_subterm_with_head_and_args hd_var n_args p.conv with
- | None ->
-   (try
-    let phase = p.phase in
+let auto p =
+ let rec aux p =
+ let hd, n_args = get_inert p.div in
+ match hd with
+ | C | L _ | B | A _  -> assert false
+ | V hd_var ->
+ let tms = get_subterms_with_head hd_var p.conv in
+ if List.exists (fun t -> snd (get_inert t) >= n_args) tms
+  then (
+    (* let tms = List.sort (fun t1 t2 -> - compare (snd (get_inert t1)) (snd (get_inert t2))) tms in *)
+    List.iter (fun t -> try
+      let js = find_eta_difference p t in
+      (* print_endline (String.concat ", " (List.map string_of_int js)); *)
+      if js = [] then problem_fail p "no eta difference found (div subterm of conv?)";
+      let js = List.rev js in
+       List.iter
+        (fun j ->
+         try
+          let k = 1 + max
+           (compute_max_lambdas_at hd_var j p.div)
+            (compute_max_lambdas_at hd_var j p.conv) in
+          ignore (aux (step j k p))
+         with Fail(_, s) ->
+          print_endline ("Backtracking (eta_diff) because: " ^ s)) js;
+       raise (Fail(-1, "no eta difference"))
+      with Fail(_, s) ->
+       print_endline ("Backtracking (get_subterms) because: " ^ s)) tms;
+     raise (Fail(-1, "no similar terms"))
+   )
+  else
+    (let phase = p.phase in
      let p = eat p in
      if phase = `Two
       then problem_fail p "Auto.2 did not complete the problem"
-      else auto p
-    with Done sigma -> sigma)
- | Some t ->
-  let j = find_eta_difference p t n_args in
-  let k = 1 + max
-   (compute_max_lambdas_at hd_var j p.div)
-    (compute_max_lambdas_at hd_var j p.conv) in
-  let p = step j k p in
-  auto p
+      else aux p)
+  in
+  try
+   aux p
+  with Done sigma -> sigma
 ;;
 
 let problem_of (label, div, convs, ps, var_names) =
@@ -334,7 +397,8 @@ let problem_of (label, div, convs, ps, var_names) =
 ;;
 
 let solve p =
- if eta_subterm p.div p.conv
+ if is_stuck p.div then print_endline "!!! div is stuck. Problem was not run !!!"
+ else if eta_subterm p.div p.conv
   then print_endline "!!! div is subterm of conv. Problem was not run !!!"
   else check p (auto p)
 ;;