| V of var\r
| A of t * t\r
| L of t\r
- | B (* bottom *)\r
- | C of int\r
+ | C (* constant *)\r
;;\r
\r
let delta = L(A(V 0, V 0));;\r
\r
+let rec is_stuck = function\r
+ | C -> true\r
+ | A(t,_) -> is_stuck t\r
+ | _ -> false\r
+;;\r
+\r
let eta_eq' =\r
let rec aux l1 l2 t1 t2 = match t1, t2 with\r
+ | _, _ when is_stuck t1 || is_stuck t2 -> true\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
- | C a, C b -> a = b\r
| A(t1,t2), A(u1,u2) -> aux l1 l2 t1 u1 && aux l1 l2 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' lev 0 u t || match t with\r
+ let rec aux lev t = if t = C then false else (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
+ | _ -> false) in\r
+ aux 0\r
;;\r
\r
-(* does NOT lift t *)\r
+(* does NOT lift the argument *)\r
let mk_lams = fold_nat (fun x _ -> L x) ;;\r
\r
let string_of_t =\r
let rec string_of_term_w_pars level = function\r
| V v -> if v >= level then "`" ^ string_of_int (v-level) else\r
string_of_bvar (level - v-1)\r
- | C n -> "c" ^ string_of_int n\r
+ | C -> "C"\r
| A _\r
| L _ as t -> "(" ^ string_of_term_no_pars level t ^ ")"\r
- | B -> "BOT"\r
and string_of_term_no_pars_app level = function\r
| A(t1,t2) -> string_of_term_no_pars_app level t1 ^ " " ^ string_of_term_w_pars level t2\r
| _ as t -> string_of_term_w_pars level t\r
; div : t\r
; conv : t\r
; sigma : (var * t) list (* substitutions *)\r
- ; stepped : var list\r
- ; phase : [`One | `Two] (* :'( *)\r
}\r
\r
let string_of_problem p =\r
let lines = [\r
- "[stepped] " ^ String.concat " " (List.map string_of_int p.stepped);\r
"[DV] " ^ string_of_t p.div;\r
"[CV] " ^ string_of_t p.conv;\r
] in\r
String.concat "\n" lines\r
;;\r
\r
+exception B;;\r
exception Done of (var * t) list (* substitution *);;\r
exception Fail of int * string;;\r
\r
{p with freshno=freshno+1}, freshno+1\r
;;\r
\r
+(* CSC: rename? is an applied C an inert?\r
+ is_inert and get_inert work inconsistently *)\r
let rec is_inert =\r
function\r
| A(t,_) -> is_inert t\r
| V _ -> true\r
- | C _\r
- | L _ | B -> false\r
+ | C\r
+ | L _ -> false\r
;;\r
\r
-let is_var = function V _ -> true | _ -> false;;\r
-let is_lambda = function L _ -> true | _ -> false;;\r
-\r
-let rec no_leading_lambdas = function\r
- | L t -> 1 + no_leading_lambdas t\r
- | _ -> 0\r
+let rec is_constant =\r
+ function\r
+ C -> true\r
+ | V _ -> false\r
+ | A(t,_)\r
+ | L t -> is_constant t\r
;;\r
\r
let rec get_inert = function\r
- | V n -> (n,0)\r
+ | V _ | C as t -> (t,0)\r
| A(t, _) -> let hd,args = get_inert t in hd,args+1\r
| _ -> assert false\r
;;\r
\r
+let args_of_inert =\r
+ let rec aux acc =\r
+ function\r
+ | V _ | C -> acc\r
+ | A(t, a) -> aux (a::acc) t\r
+ | _ -> assert false\r
+ in\r
+ aux []\r
+;;\r
+\r
+(* precomputes the number of leading lambdas in a term,\r
+ after replacing _v_ w/ a term starting with n lambdas *)\r
+let rec no_leading_lambdas v n = function\r
+ | L t -> 1 + no_leading_lambdas (v+1) n t\r
+ | A _ as t -> let v', m = get_inert t in if V v = v' then max 0 (n - m) else 0\r
+ | V v' -> if v = v' then n else 0\r
+ | C -> 0\r
+;;\r
+\r
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
let t1 = subst level delift sub t1 in\r
let t2 = subst level delift sub t2 in\r
mk_app t1 t2\r
- | C _ as t -> t\r
- | B -> B\r
-and mk_app t1 t2 = if t2 = B || (t1 = delta && t2 = delta) then B\r
+ | C -> C\r
+and mk_app t1 t2 = if t1 = delta && t2 = delta then raise B\r
else match t1 with\r
- | C _ as t -> t\r
- | B -> B\r
| L t1 -> subst 0 true (0, t2) t1\r
| _ -> A (t1, t2)\r
and lift n =\r
| V m -> V (if m >= lev then m + n else m)\r
| L t -> L (aux (lev+1) t)\r
| A (t1, t2) -> A (aux lev t1, aux lev t2)\r
- | C _ as t -> t\r
- | B -> B\r
+ | C -> C\r
in aux 0\r
;;\r
let subst = subst 0 false;;\r
\r
-let subst_in_problem (sub: var * t) (p: problem) =\r
-print_endline ("-- SUBST " ^ string_of_t (V (fst sub)) ^ " |-> " ^ string_of_t (snd sub));\r
+let subst_in_problem ((v, t) as sub) p =\r
+print_endline ("-- SUBST " ^ string_of_t (V v) ^ " |-> " ^ string_of_t t);\r
{p with\r
div=subst sub p.div;\r
conv=subst sub p.conv;\r
- stepped=(fst sub)::p.stepped;\r
sigma=sub::p.sigma}\r
;;\r
\r
-let get_subterm_with_head_and_args hd_var n_args =\r
- let rec aux lev = function\r
- | C _\r
- | V _ | B -> None\r
- | L t -> aux (lev+1) t\r
+let get_subterms_with_head hd_var =\r
+ let rec aux lev inert_done = function\r
+ | L t -> aux (lev+1) false t\r
+ | C | V _ -> []\r
| A(t1,t2) as t ->\r
let hd_var', n_args' = get_inert t1 in\r
- if hd_var' = hd_var + lev && n_args <= 1 + n_args'\r
- then Some (lift ~-lev t)\r
- else match aux lev t2 with\r
- | None -> aux lev t1\r
- | Some _ as res -> res\r
- in aux 0\r
+ if not inert_done && hd_var' = V (hd_var + lev)\r
+ then lift ~-lev t :: aux lev true t1 @ aux lev false t2\r
+ else aux lev true t1 @ aux lev false t2\r
+ in aux 0 false\r
;;\r
\r
let rec purify = function\r
| L t -> Pure.L (purify t)\r
| A (t1,t2) -> Pure.A (purify t1, purify t2)\r
| V n -> Pure.V n\r
- | C _ -> Pure.V max_int (* FIXME *)\r
- | B -> Pure.B\r
+ | C -> Pure.V (min_int/2)\r
;;\r
\r
let check p sigma =\r
let div = purify p.div in\r
let conv = purify p.conv in\r
let sigma = List.map (fun (v,t) -> v, purify t) sigma in\r
- let freshno = List.fold_right (fun (x,_) -> max x) sigma 0 in\r
+ let freshno = List.fold_right (max ++ fst) sigma 0 in\r
let env = Pure.env_of_sigma freshno sigma in\r
assert (Pure.diverged (Pure.mwhd (env,div,[])));\r
print_endline " D diverged.";\r
\r
let sanity p =\r
print_endline (string_of_problem p); (* non cancellare *)\r
- if p.conv = B then problem_fail p "p.conv diverged";\r
- if p.div = B then raise (Done p.sigma);\r
- if p.phase = `Two && p.div = delta then raise (Done p.sigma);\r
if not (is_inert p.div) then problem_fail p "p.div converged";\r
+ (* Trailing constant args can be removed because do not contribute to eta-diff *)\r
+ let rec remove_trailing_constant_args = function\r
+ | A(t1, t2) when is_constant t2 -> remove_trailing_constant_args t1\r
+ | _ as t -> t in\r
+ let p = {p with div=remove_trailing_constant_args p.div} in\r
p\r
;;\r
\r
in snd (aux t)\r
;;\r
\r
-let find_eta_difference p t n_args =\r
- let t = inert_cut_at n_args t in\r
- let rec aux t u k = match t, u with\r
- | V _, V _ -> assert false (* div subterm of conv *)\r
- | A(t1,t2), A(u1,u2) ->\r
- if not (eta_eq t2 u2) then (print_endline((string_of_t t2) ^ " <> " ^ (string_of_t u2)); k)\r
- else aux t1 u1 (k-1)\r
- | _, _ -> assert false\r
- in aux p.div t n_args\r
+(* return the index of the first argument with a difference\r
+ (the first argument is 0) *)\r
+let find_eta_difference p t =\r
+ let divargs = args_of_inert p.div in\r
+ let conargs = args_of_inert t in\r
+ let rec aux k divargs conargs =\r
+ match divargs,conargs with\r
+ [],_ -> []\r
+ | _::_,[] -> [k]\r
+ | t1::divargs,t2::conargs ->\r
+ (if not (eta_eq t1 t2) then [k] else []) @ aux (k+1) divargs conargs\r
+ in\r
+ aux 0 divargs conargs\r
;;\r
\r
let compute_max_lambdas_at hd_var j =\r
let rec aux hd = function\r
| A(t1,t2) ->\r
- (if get_inert t1 = (hd, j)\r
+ (if get_inert t1 = (V hd, j)\r
then max ( (*FIXME*)\r
- if is_inert t2 && let hd', j' = get_inert t2 in hd' = hd\r
+ if is_inert t2 && let hd', j' = get_inert t2 in hd' = V hd\r
then let hd', j' = get_inert t2 in j - j'\r
- else no_leading_lambdas t2)\r
+ else no_leading_lambdas hd_var j t2)\r
else id) (max (aux hd t1) (aux hd t2))\r
| L t -> aux (hd+1) t\r
- | V _ -> 0\r
- | _ -> assert false\r
+ | V _ | C -> 0\r
in aux hd_var\r
;;\r
\r
let print_cmd s1 s2 = print_endline (">> " ^ s1 ^ " " ^ s2);;\r
\r
-(* eat the arguments of the divergent and explode.\r
- It does NOT perform any check, may fail if done unsafely *)\r
-let eat p =\r
-print_cmd "EAT" "";\r
- let var, k = get_inert p.div in\r
- let phase = p.phase in\r
- let p, t =\r
- match phase with\r
- | `One ->\r
- let n = 1 + max\r
- (compute_max_lambdas_at var k p.div)\r
- (compute_max_lambdas_at var k p.conv) in\r
- (* apply fresh vars *)\r
- let p, t = fold_nat (fun (p, t) _ ->\r
- let p, v = freshvar p in\r
- p, A(t, V (v + k))\r
- ) (p, V 0) n in\r
- let p = {p with phase=`Two} in p, A(t, delta)\r
- | `Two -> p, delta in\r
- let subst = var, mk_lams t k in\r
- let p = subst_in_problem subst p in\r
- sanity p;\r
- let p = if phase = `One then {p with div = (match p.div with A(t,_) -> t | _ -> assert false)} else p in\r
- sanity p\r
+(* returns Some i if i is the smallest integer s.t. p holds for the i-th\r
+ element of the list in input *)\r
+let smallest_such_that p =\r
+ let rec aux i =\r
+ function\r
+ [] -> None\r
+ | hd::_ when (print_endline (string_of_t hd) ; p hd) -> Some i\r
+ | _::tl -> aux (i+1) tl\r
+ in\r
+ aux 0\r
;;\r
\r
(* step on the head of div, on the k-th argument, with n fresh vars *)\r
let step k n p =\r
- let var, _ = get_inert p.div in\r
-print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (of:" ^ string_of_int n ^ ")");\r
+ let hd, _ = get_inert p.div in\r
+ match hd with\r
+ | C | L _ | A _ -> assert false\r
+ | V var ->\r
+print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (on " ^ string_of_int (k+1) ^ "th)");\r
let p, t = (* apply fresh vars *)\r
fold_nat (fun (p, t) _ ->\r
let p, v = freshvar p in\r
let p = subst_in_problem subst p in\r
sanity p\r
;;\r
+\r
+let finish p =\r
+ (* one-step version of eat *)\r
+ let compute_max_arity =\r
+ let rec aux n = function\r
+ | A(t1,t2) -> max (aux (n+1) t1) (aux 0 t2)\r
+ | L t -> max n (aux 0 t)\r
+ | _ -> n\r
+ in aux 0 in\r
+print_cmd "FINISH" "";\r
+ (* First, a step on the last argument of the divergent.\r
+ Because of the sanity check, it will never be a constant term. *)\r
+ let div_hd, div_nargs = get_inert p.div in\r
+ let div_hd = match div_hd with V n -> n | _ -> assert false in\r
+ let j = div_nargs - 1 in\r
+ let arity = compute_max_arity p.conv in\r
+ let n = 1 + arity + max\r
+ (compute_max_lambdas_at div_hd j p.div)\r
+ (compute_max_lambdas_at div_hd j p.conv) in\r
+ let p = step j n p in\r
+ (* Now, find first argument of div that is a variable never applied anywhere.\r
+ It must exist because of some invariant, since we just did a step,\r
+ and because of the arity of the divergent *)\r
+ let div_hd, div_nargs = get_inert p.div in\r
+ let div_hd = match div_hd with V n -> n | _ -> assert false in\r
+ let rec aux m = function\r
+ | A(t, V delta_var) ->\r
+ if delta_var <> div_hd && get_subterms_with_head delta_var p.conv = []\r
+ then m, delta_var\r
+ else aux (m-1) t\r
+ | A(t,_) -> aux (m-1) t\r
+ | _ -> assert false in\r
+ let m, delta_var = aux div_nargs p.div in\r
+ let p = subst_in_problem (delta_var, delta) p in\r
+ let p = subst_in_problem (div_hd, mk_lams delta (m-1)) p in\r
+ sanity p\r
;;\r
\r
-let parse strs =\r
- let rec aux level = function\r
- | Parser_andrea.Lam t -> L (aux (level + 1) t)\r
- | Parser_andrea.App (t1, t2) ->\r
- if level = 0 then mk_app (aux level t1) (aux level t2)\r
- else A(aux level t1, aux level t2)\r
- | Parser_andrea.Var v -> V v in\r
- let (tms, free) = Parser_andrea.parse_many strs in\r
- (List.map (aux 0) tms, free)\r
+let auto p =\r
+ let rec aux p =\r
+ let hd, n_args = get_inert p.div in\r
+ match hd with\r
+ | C | L _ | A _ -> assert false\r
+ | V hd_var ->\r
+ let tms = get_subterms_with_head hd_var p.conv in\r
+ if List.exists (fun t -> snd (get_inert t) >= n_args) tms\r
+ then (\r
+ (* let tms = List.sort (fun t1 t2 -> - compare (snd (get_inert t1)) (snd (get_inert t2))) tms in *)\r
+ List.iter (fun t -> try\r
+ let js = find_eta_difference p t in\r
+ (* print_endline (String.concat ", " (List.map string_of_int js)); *)\r
+ if js = [] then problem_fail p "no eta difference found (div subterm of conv?)";\r
+ let js = List.rev js in\r
+ List.iter\r
+ (fun j ->\r
+ try\r
+ let k = 1 + max\r
+ (compute_max_lambdas_at hd_var j p.div)\r
+ (compute_max_lambdas_at hd_var j p.conv) in\r
+ ignore (aux (step j k p))\r
+ with Fail(_, s) ->\r
+ print_endline ("Backtracking (eta_diff) because: " ^ s)) js;\r
+ raise (Fail(-1, "no eta difference"))\r
+ with Fail(_, s) ->\r
+ print_endline ("Backtracking (get_subterms) because: " ^ s)) tms;\r
+ raise (Fail(-1, "no similar terms"))\r
+ )\r
+ else\r
+ problem_fail (finish p) "Finish did not complete the problem"\r
+ in\r
+ try\r
+ aux p\r
+ with Done sigma -> sigma\r
;;\r
\r
-let problem_of div conv =\r
+let problem_of (label, div, convs, ps, var_names) =\r
print_hline ();\r
- let [@warning "-8"] [div; conv], var_names = parse ([div; conv]) in\r
+ let rec aux lev = function\r
+ | `Lam(_, t) -> L (aux (lev+1) t, [])\r
+ | `I (v, args) -> Listx.fold_left (fun x y -> fst (mk_app x (aux lev y))) (aux lev (`Var v)) args\r
+ | `Var(v,_) -> if v >= lev && List.nth var_names (v-lev) = "C" then C else V v\r
+ | `N _ | `Match _ -> assert false in\r
+ assert (List.length ps = 0);\r
+ let convs = List.rev convs in\r
+ let conv = List.fold_left (fun x y -> fst (mk_app x (aux 0 (y :> Num.nf)))) (V (List.length var_names)) convs in\r
+ let var_names = "@" :: var_names in\r
+ let div = match div with\r
+ | Some div -> aux 0 (div :> Num.nf)\r
+ | None -> assert false in\r
let varno = List.length var_names in\r
- let p = {orig_freshno=varno; freshno=1+varno; div; conv; sigma=[]; stepped=[]; phase=`One} in\r
- (* initial sanity check *)\r
- sanity p\r
+ {orig_freshno=varno; freshno=1+varno; div; conv; sigma=[]}\r
;;\r
\r
-let exec div conv cmds =\r
- let p = problem_of div conv in\r
- try\r
- problem_fail (List.fold_left (|>) p cmds) "Problem not completed"\r
- with\r
- | Done _ -> ()\r
+let solve p =\r
+ if is_constant p.div\r
+ then print_endline "!!! div is stuck. Problem was not run !!!"\r
+ else if eta_subterm p.div p.conv\r
+ then print_endline "!!! div is subterm of conv. Problem was not run !!!"\r
+ else let p = sanity p (* initial sanity check *) in check p (auto p)\r
;;\r
\r
-let rec auto p =\r
- let hd_var, n_args = get_inert p.div in\r
- match get_subterm_with_head_and_args hd_var n_args p.conv with\r
- | None ->\r
- (try\r
- let phase = p.phase in\r
- let p = eat p in\r
- if phase = `Two\r
- then problem_fail p "Auto.2 did not complete the problem"\r
- else auto p\r
- with Done sigma -> sigma)\r
- | Some t ->\r
- let j = find_eta_difference p t n_args - 1 in\r
- let k = 1 + max\r
- (compute_max_lambdas_at hd_var j p.div)\r
- (compute_max_lambdas_at hd_var j p.conv) in\r
- let p = step j k p in\r
- auto p\r
-;;\r
+Problems.main (solve ++ problem_of);\r
\r
-let interactive div conv cmds =\r
+(* Example usage of interactive: *)\r
+\r
+(* let interactive div conv cmds =\r
let p = problem_of div conv in\r
try (\r
let p = List.fold_left (|>) p cmds in\r
| Done _ -> print_endline "Done! Commands history: "; List.iter print_endline (List.rev cmds)\r
in f p []\r
) with Done _ -> ()\r
-;;\r
-\r
-let rec conv_join = function\r
- | [] -> "@"\r
- | x::xs -> conv_join xs ^ " ("^ x ^")"\r
-;;\r
-\r
-let auto' a b =\r
- let p = problem_of a (conv_join b) in\r
- let sigma = auto p in\r
- check p sigma\r
-;;\r
-\r
-(* Example usage of exec, interactive:\r
-\r
-exec\r
- "x x"\r
- (conv_join["x y"; "y y"; "y x"])\r
- [ step 0 1; eat ]\r
-;;\r
+;; *)\r
\r
-interactive "x y"\r
+(* interactive "x y"\r
"@ (x x) (y x) (y z)" [step 0 1; step 0 2; eat]\r
-;;\r
-\r
-*)\r
-\r
-auto' "x x" ["x y"; "y y"; "y x"] ;;\r
-auto' "x y" ["x (_. x)"; "y z"; "y x"] ;;\r
-auto' "a (x. x b) (x. x c)" ["a (x. b b) @"; "a @ c"; "a (x. x x) a"; "a (a a a) (a c c)"] ;;\r
-\r
-auto' "x (y. x y y)" ["x (y. x y x)"] ;;\r
-\r
-auto' "x a a a a" [\r
- "x b a a a";\r
- "x a b a a";\r
- "x a a b a";\r
- "x a a a b";\r
-] ;;\r
-\r
-(* Controesempio ad usare un conto dei lambda che non considere le permutazioni *)\r
-auto' "x a a a a (x (x. x x) @ @ (_._.x. x x) x) b b b" [\r
- "x a a a a (_. a) b b b";\r
- "x a a a a (_. _. _. _. x. y. x y)";\r
-] ;;\r
-\r
-\r
-print_hline();\r
-print_endline "ALL DONE. "\r
-\r
-let solve div convs =\r
- let p = problem_of div (conv_join convs) in\r
- if eta_subterm p.div p.conv\r
- then print_endline "!!! div is subterm of conv. Problem was not run !!!"\r
- else check p (auto p)\r
-;;\r
+;; *)\r
projects / fireball-separation.git / blobdiff