sidekick/src/core/formula_intf.ml
2016-08-03 20:27:51 +02:00

42 lines
1.1 KiB
OCaml

(*
MSAT is free software, using the Apache license, see file LICENSE
Copyright 2014 Guillaume Bury
Copyright 2014 Simon Cruanes
*)
type negated =
| Negated (* changed sign *)
| Same_sign (* kept sign *)
module type S = sig
(** Signature of formulas that parametrises the SAT/SMT Solver Module. *)
type t
(** The type of atomic formulas. *)
type proof
(** An abstract type for proofs *)
val dummy : t
(** Formula constants. A valid formula should never be physically equal to [dummy] *)
val fresh : unit -> t
(** Returns a fresh literal, distinct from any other literal (used in cnf conversion) *)
val neg : t -> t
(** Formula negation *)
val norm : t -> t * negated
(** Returns a 'normalized' form of the formula, possibly negated
(in which case return [Negated]).
[norm] must be so that [a] and [neg a] normalise to the same formula,
but one returns [Same_sign] and one returns [Negated] *)
val hash : t -> int
val equal : t -> t -> bool
(** Usual hash and comparison functions. Given to Hashtbl functors. *)
val print : Format.formatter -> t -> unit
(** Printing function used for debugging. *)
end