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fix(thbool): fix non-termination issue by creating clauses at most once

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This commit is contained in:
Simon Cruanes 2019-02-10 16:24:04 -06:00
parent b5208da56c
commit 62ea8fd0cb
1 changed files with 15 additions and 9 deletions
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24
src/th-bool/Sidekick_th_bool.ml
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@ -160,6 +160,7 @@ end
type t = {
tst: Term.state;
expanded: unit Term.Tbl.t; (* set of literals already expanded *)
}
let pp_c out c = Fmt.fprintf out "(@[<hv>%a@])" (Util.pp_list Lit.pp) c
@ -167,6 +168,11 @@ let pp_c out c = Fmt.fprintf out "(@[<hv>%a@])" (Util.pp_list Lit.pp) c
let tseitin ~final (self:t) (acts:Theory.actions) (lit:Lit.t) (lit_t:term) (v:term view) : unit =
let (module A) = acts in
Log.debugf 5 (fun k->k "(@[th_bool.tseitin@ %a@])" Lit.pp lit);
let expanded () = Term.Tbl.mem self.expanded lit_t in
let add_axiom c =
Term.Tbl.replace self.expanded lit_t ();
A.add_persistent_axiom c
in
match v with
| B_not _ -> assert false (* normalized *)
| B_atom _ | B_eq _ -> () (* CC will manage *)
@ -174,7 +180,7 @@ let tseitin ~final (self:t) (acts:Theory.actions) (lit:Lit.t) (lit_t:term) (v:te
let l = IArray.to_list l in
if Lit.sign lit then (
A.propagate_distinct l ~neq:lit_t lit
) else if final then (
) else if final && not @@ expanded () then (
(* add clause [distinct t1…tn ∨ ∨_{i,j>i} t_i=j] *)
let c =
Sequence.diagonal_l l
@ -183,7 +189,7 @@ let tseitin ~final (self:t) (acts:Theory.actions) (lit:Lit.t) (lit_t:term) (v:te
in
let c = Lit.neg lit :: c in
Log.debugf 5 (fun k->k "(@[tseitin.distinct.case-split@ %a@])" pp_c c);
A.add_local_axiom c
add_axiom c
)
| B_and subs ->
if Lit.sign lit then (
@ -193,11 +199,11 @@ let tseitin ~final (self:t) (acts:Theory.actions) (lit:Lit.t) (lit_t:term) (v:te
let sublit = Lit.atom sub in
A.propagate sublit [lit])
subs
) else if final then (
) else if final && not @@ expanded () then (
(* axiom [¬lit => ∨_i ¬ subs_i] *)
let subs = IArray.to_list subs in
let c = Lit.neg lit :: List.map (Lit.atom ~sign:false) subs in
A.add_local_axiom c
add_axiom c
)
| B_or subs ->
if not @@ Lit.sign lit then (
@ -207,18 +213,18 @@ let tseitin ~final (self:t) (acts:Theory.actions) (lit:Lit.t) (lit_t:term) (v:te
let sublit = Lit.atom ~sign:false sub in
A.add_local_axiom [Lit.neg lit; sublit])
subs
) else if final then (
) else if final && not @@ expanded () then (
(* axiom [lit => ∨_i subs_i] *)
let subs = IArray.to_list subs in
let c = Lit.neg lit :: List.map (Lit.atom ~sign:true) subs in
A.add_local_axiom c
add_axiom c
)
| B_imply (guard,concl) ->
if Lit.sign lit && final then (
if Lit.sign lit && final && not @@ expanded () then (
(* axiom [lit => ∨_i ¬guard_i ∨ concl] *)
let guard = IArray.to_list guard in
let c = Lit.atom concl :: Lit.neg lit :: List.map (Lit.atom ~sign:false) guard in
A.add_local_axiom c
add_axiom c
) else if not @@ Lit.sign lit then (
(* propagate [¬lit => ¬concl] *)
A.propagate (Lit.atom ~sign:false concl) [lit];
@ -249,6 +255,6 @@ let th =
~partial_check
~final_check
~name:"boolean"
~create:(fun tst -> {tst})
~create:(fun tst -> {tst; expanded=Term.Tbl.create 24})
?mk_model:None (* entirely interpreted *)
()