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(********************************************************************)
(* *)
(* The Why3 Verification Platform / The Why3 Development Team *)
(* Copyright 2010-2025 -- Inria - CNRS - Paris-Saclay University *)
(* *)
(* This software is distributed under the terms of the GNU Lesser *)
(* General Public License version 2.1, with the special exception *)
(* on linking described in file LICENSE. *)
(********************************************************************)
open Why3
(* push negations down *)
(* BEGIN{negate} *)
open Term
let rec negate (t:term) : term =
match t.t_node with
| Ttrue -> t_false
| Tfalse -> t_true
| Tnot t -> t
| Tbinop(Tand,t1,t2) -> t_or (negate t1) (negate t2)
| Tbinop(Tor,t1,t2) -> t_and (negate t1) (negate t2)
| Tquant(Tforall,tq) ->
let vars,triggers,t' = t_open_quant tq in
let tq' = t_close_quant vars triggers (negate t') in
t_exists tq'
| Tquant(Texists,tq) ->
let vars,triggers,t' = t_open_quant tq in
let tq' = t_close_quant vars triggers (negate t') in
t_forall tq'
| _ -> t_not t
let rec traverse (t:term) : term =
match t.t_node with
| Tnot t -> t_map traverse (negate t)
| _ -> t_map traverse t
(* END{negate} *)
(* BEGIN{register} *)
let negate_goal pr t = [Decl.create_prop_decl Decl.Pgoal pr (traverse t)]
let negate_trans = Trans.goal negate_goal
let () = Trans.register_transform
"push_negations_down" negate_trans
~desc:"In the current goal,@ push negations down,@ \
across logical connectives."
(* END{register} *)
|
