(* ========================================================================= *)
(* CNF PROBLEMS *)
(* Copyright (c) 2001 Joe Hurd, distributed under the BSD License *)
(* ========================================================================= *)
signature Problem =
sig
(* ------------------------------------------------------------------------- *)
(* Problems. *)
(* ------------------------------------------------------------------------- *)
type problem =
{axioms : Thm.clause list,
conjecture : Thm.clause list}
val size : problem -> {clauses : int,
literals : int,
symbols : int,
typedSymbols : int}
val freeVars : problem -> NameSet.set
val toClauses : problem -> Thm.clause list
val toFormula : problem -> Formula.formula
val toGoal : problem -> Formula.formula
val toString : problem -> string
(* ------------------------------------------------------------------------- *)
(* Categorizing problems. *)
(* ------------------------------------------------------------------------- *)
datatype propositional =
Propositional
| EffectivelyPropositional
| NonPropositional
datatype equality =
NonEquality
| Equality
| PureEquality
datatype horn =
Trivial
| Unit
| DoubleHorn
| Horn
| NegativeHorn
| NonHorn
type category =
{propositional : propositional,
equality : equality,
horn : horn}
val categorize : problem -> category
val categoryToString : category -> string
end