simon/sidekick
1
0
Fork 0
mirror of https://github.com/c-cube/sidekick.git synced 2025-12-06 03:05:31 -05:00
Code Issues Projects Releases Packages Wiki Activity Actions

[bugfix] Sort false atoms by levels in new clauses

Browse source 
When a new clauses is added and it is a conflict (i.e all atoms
are false), one must take care of which literals to watch.
In order to work, the watched literals must be those with the higher
decision levels, or else the watched literals might not react when
needed. This is fixed by sorting the literals in decreasing order of
decision level when adding a new clause which happens to be false in the
current trail.
This commit is contained in:
Guillaume Bury 2016-07-16 15:55:26 +02:00
parent 1acecc0815
commit 9dadb67fc9
4 changed files with 42 additions and 50 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

67
solver/internal.ml
View file

@ -304,7 +304,8 @@ module Make
let partition atoms =
(* Parittion litterals for new clauses *)
let rec partition_aux trues unassigned falses history = function
| [] -> trues @ unassigned @ falses, history
| [] ->
trues @ unassigned @ falses, history
| a :: r ->
if a.is_true then
if a.var.v_level = 0 then raise Trivial
@ -352,27 +353,18 @@ module Make
(* Adding/removing clauses *)
let attach_clause c =
if not c.attached then begin
Log.debugf 60 "Attaching %a" (fun k -> k St.pp_clause c);
c.attached <- true;
Vec.push (Vec.get c.atoms 0).neg.watched c;
Vec.push (Vec.get c.atoms 1).neg.watched c;
if c.learnt then
env.learnts_literals <- env.learnts_literals + Vec.size c.atoms
else
env.clauses_literals <- env.clauses_literals + Vec.size c.atoms
end
let detach_clause c =
if c.attached then begin
c.attached <- false;
Log.debugf 10 "Removing clause @[%a@]" (fun k->k St.pp_clause c);
(* Not necessary, cleanup is done during propagation
Vec.remove (Vec.get c.atoms 0).neg.watched c;
Vec.remove (Vec.get c.atoms 1).neg.watched c;
*)
if c.learnt then
env.learnts_literals <- env.learnts_literals - Vec.size c.atoms
else
env.clauses_literals <- env.clauses_literals - Vec.size c.atoms
Vec.remove (Vec.get c.atoms 0).neg.watched c;
Vec.remove (Vec.get c.atoms 1).neg.watched c;
end
let remove_clause c = detach_clause c
@ -383,6 +375,7 @@ module Make
(* cancel down to [lvl] excluded *)
let cancel_until lvl =
if decision_level () > lvl then begin
Log.debugf 5 "Backtracking to lvl %d" (fun k -> k lvl);
env.elt_head <- Vec.get env.elt_levels lvl;
env.th_head <- env.elt_head;
for c = env.elt_head to Vec.size env.elt_queue - 1 do
@ -424,10 +417,8 @@ module Make
begin match l with
| [ a ] ->
if history = [] then r
else begin
let tmp_cl = make_clause (fresh_tname ()) l 1 true (History (cl :: history)) in
Bcp tmp_cl
end
else
Bcp (make_clause (fresh_tname ()) l 1 (History (cl :: history)))
| _ -> assert false
end
| r -> r
@ -522,7 +513,8 @@ module Make
end
done; assert false
with Exit ->
let learnt = List.sort (fun a b -> Pervasives.compare b.var.v_level a.var.v_level) !c in
let learnt = List.fast_sort (
fun a b -> Pervasives.compare b.var.v_level a.var.v_level) !c in
let blevel = backtrack_lvl !is_uip learnt in
blevel, learnt, List.rev !history, !is_uip
@ -542,7 +534,10 @@ module Make
let history = ref [] in
assert (decision_level () > 0);
while !cond do
if !c.learnt then clause_bump_activity !c;
begin match !c.cpremise with
| History _ -> clause_bump_activity !c
| Hyp _ | Lemma _ -> ()
end;
history := !c :: !history;
(* visit the current predecessors *)
for j = 0 to Vec.size !c.atoms - 1 do
@ -601,13 +596,13 @@ module Make
report_unsat confl
else begin
let name = fresh_lname () in
let uclause = make_clause name learnt (List.length learnt) true history in
let uclause = make_clause name learnt (List.length learnt) history in
Vec.push env.clauses_learnt uclause;
enqueue_bool fuip 0 (Bcp uclause)
end
| fuip :: _ ->
let name = fresh_lname () in
let lclause = make_clause name learnt (List.length learnt) true history in
let lclause = make_clause name learnt (List.length learnt) history in
Vec.push env.clauses_learnt lclause;
attach_clause lclause;
clause_bump_activity lclause;
@ -643,7 +638,7 @@ module Make
let clause =
if history = [] then init
else make_clause ?tag:init.tag (fresh_name ())
atoms size true (History (init :: history))
atoms size (History (init :: history))
in
Log.debugf 4 "New clause:@ @[%a@]" (fun k->k St.pp_clause clause);
Vec.push vec clause;
@ -651,15 +646,18 @@ module Make
| [] ->
report_unsat clause
| a::b::_ ->
attach_clause clause;
if a.neg.is_true then begin
let lvl = List.fold_left (fun m a -> max m a.var.v_level) 0 atoms in
cancel_until lvl;
add_boolean_conflict clause
end else if b.neg.is_true && not a.is_true && not a.neg.is_true then begin
let lvl = List.fold_left (fun m a -> max m a.var.v_level) 0 atoms in
cancel_until lvl;
enqueue_bool a lvl (Bcp clause)
Vec.sort clause.atoms (fun a b ->
compare b.var.v_level a.var.v_level);
attach_clause clause;
add_boolean_conflict init
end else begin
attach_clause clause;
if b.neg.is_true && not a.is_true && not a.neg.is_true then begin
let lvl = List.fold_left (fun m a -> max m a.var.v_level) 0 atoms in
cancel_until lvl;
enqueue_bool a lvl (Bcp clause)
end
end
| [a] ->
Log.debugf 5 "New unit clause, propagating : %a" (fun k->k St.pp_atom a);
@ -681,8 +679,7 @@ module Make
(* true clause, keep it in watched *)
Vec.set watched !new_sz c;
incr new_sz;
end
else
end else
try (* look for another watch lit *)
for k = 2 to Vec.size atoms - 1 do
let ak = Vec.get atoms k in
@ -743,7 +740,7 @@ module Make
let atoms = List.rev_map (fun x -> new_atom x) l in
Iheap.grow_to_by_double env.order (St.nb_elt ());
List.iter (fun a -> insert_var_order (elt_of_var a.var)) atoms;
let c = make_clause (fresh_tname ()) atoms (List.length atoms) true (Lemma lemma) in
let c = make_clause (fresh_tname ()) atoms (List.length atoms) (Lemma lemma) in
add_clause c
let slice_propagate f lvl =
@ -781,7 +778,7 @@ module Make
let l = List.rev_map new_atom l in
Iheap.grow_to_by_double env.order (St.nb_elt ());
List.iter (fun a -> insert_var_order (elt_of_var a.var)) l;
let c = St.make_clause (St.fresh_tname ()) l (List.length l) true (Lemma p) in
let c = St.make_clause (St.fresh_tname ()) l (List.length l) (Lemma p) in
Some c
end
@ -963,7 +960,7 @@ module Make
let add_clauses ?tag cnf =
let aux cl =
let c = make_clause ?tag (fresh_hname ())
cl (List.length cl) false (Hyp (current_level ())) in
cl (List.length cl) (Hyp (current_level ())) in
add_clause c;
(* Clauses can be added after search has begun (and thus we are not at level 0,
so better not do anything at this point.

9
solver/res.ml
View file

@ -83,7 +83,7 @@ module Make(St : Solver_types.S) = struct
cmp_cl (to_list c) (to_list d)
let prove conclusion =
assert St.(conclusion.learnt || conclusion.cpremise <> History []);
assert St.(conclusion.cpremise <> History []);
conclusion
let prove_unsat c =
@ -93,7 +93,7 @@ module Make(St : Solver_types.S) = struct
| Some St.Bcp d -> d
| _ -> assert false) l
in
St.make_clause (fresh_pcl_name ()) [] 0 true (St.History (c :: l))
St.make_clause (fresh_pcl_name ()) [] 0 (St.History (c :: l))
let prove_atom a =
if St.(a.is_true && a.var.v_level = 0) then begin
@ -126,8 +126,8 @@ module Make(St : Solver_types.S) = struct
begin match r with
| [] -> (l, c, d, a)
| _ ->
let new_clause = St.make_clause (fresh_pcl_name ()) l (List.length l) true
(St.History [c; d]) in
let new_clause = St.make_clause (fresh_pcl_name ())
l (List.length l) (St.History [c; d]) in
chain_res (new_clause, l) r
end
| _ -> assert false
@ -140,7 +140,6 @@ module Make(St : Solver_types.S) = struct
| St.Lemma l ->
{conclusion; step = Lemma l; }
| St.Hyp _ ->
assert (not conclusion.St.learnt);
{ conclusion; step = Hypothesis; }
| St.History [] ->
assert false

13
solver/solver_types.ml
View file

@ -58,7 +58,6 @@ module McMake (E : Expr_intf.S)(Dummy : sig end) = struct
name : string;
tag : int option;
atoms : atom Vec.t;
learnt : bool;
c_level : int;
mutable cpremise : premise;
mutable activity : float;
@ -106,7 +105,6 @@ module McMake (E : Expr_intf.S)(Dummy : sig end) = struct
activity = -1.;
attached = false;
c_level = -1;
learnt = false;
visited = false;
cpremise = History [] }
@ -182,7 +180,7 @@ module McMake (E : Expr_intf.S)(Dummy : sig end) = struct
let var, negated = make_boolean_var lit in
if negated then var.na else var.pa
let make_clause ?tag name ali sz_ali is_learnt premise =
let make_clause ?tag name ali sz_ali premise =
let atoms = Vec.from_list ali sz_ali dummy_atom in
let level =
match premise with
@ -195,12 +193,11 @@ module McMake (E : Expr_intf.S)(Dummy : sig end) = struct
atoms = atoms;
attached = false;
visited = false;
learnt = is_learnt;
c_level = level;
activity = 0.;
cpremise = premise}
let empty_clause = make_clause "Empty" [] 0 false (History [])
let empty_clause = make_clause "Empty" [] 0 (History [])
(* Decisions & propagations *)
type t = (lit, atom) Either.t
@ -298,9 +295,9 @@ module McMake (E : Expr_intf.S)(Dummy : sig end) = struct
let pp_atoms_vec out vec =
Vec.print ~sep:"" pp_atom out vec
let pp_clause out {name=name; atoms=arr; cpremise=cp; learnt=learnt} =
Format.fprintf out "%s%s@[<hov>{@[<hov>%a@]}@ cpremise={@[<hov>%a@]}@]"
name (if learnt then "!" else ":") pp_atoms_vec arr pp_premise cp
let pp_clause out {name=name; atoms=arr; cpremise=cp; } =
Format.fprintf out "%s@[<hov>{@[<hov>%a@]}@ cpremise={@[<hov>%a@]}@]"
name pp_atoms_vec arr pp_premise cp
end

3
solver/solver_types_intf.ml
View file

@ -53,7 +53,6 @@ module type S = sig
name : string;
tag : int option;
atoms : atom Vec.t;
learnt : bool;
c_level : int;
mutable cpremise : premise;
mutable activity : float;
@ -117,7 +116,7 @@ module type S = sig
val empty_clause : clause
(** The empty clause *)
val make_clause : ?tag:int -> string -> atom list -> int -> bool -> premise -> clause
val make_clause : ?tag:int -> string -> atom list -> int -> premise -> clause
(** [make_clause name atoms size learnt premise] creates a clause with the given attributes. *)
(** {2 Clause names} *)