Module org.chocosolver

Package org.chocosolver.solver.constraints.nary.cnf

Class LogicTreeToolBox

java.lang.Object

org.chocosolver.solver.constraints.nary.cnf.LogicTreeToolBox

public class LogicTreeToolBox
extends Object

A tool box to convert logical expressions into CNF.

Since:

23 nov. 2010

Author:

Charles Prud'homme, Xavier Lorca

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	LogicTreeToolBox()	This class is a factory, no need to create it.

Method Summary

Modifier and Type	Method	Description
static LogOp	developOr(LogOp n)	Moves down 'OR' operand in the logical expression n.
static LogOp	distribute(LogOp n)	Distributes 'OR's inwards over 'AND's in n
static void	expandNot(LogOp n)	Erases 'NOT' operand from the logical expression n by flipping the right children
static void	merge(LogOp.Operator op, LogOp n)	Flattens a logical expression n based on operator op.
static ILogical	simplify(ILogical t, Model model)	Detects tautologies and contradictions from t
static ILogical	simplifySingleton(ILogical l, Model model)	Remove tautologies from l
static ILogical	toCNF(LogOp logOp, Model model)	Warning: if there is a bug, please check the CNF build is like: - lit OR lit ...

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LogicTreeToolBox

protected LogicTreeToolBox()

This class is a factory, no need to create it.

Method Detail

toCNF

public static ILogical toCNF(LogOp logOp,
                             Model model)

Warning: if there is a bug, please check the CNF build is like: - lit OR lit ... OR lit - (lit OR lit ... OR lit) AND (lit OR lit ... OR lit) ... AND (lit OR lit ... OR lit)

Parameters:

logOp - logical operator

model - the model in which the logical expression will be added, useful since the expression may only be made of TRUE and FALSE.

Returns:

a CNF logical expression

expandNot

public static void expandNot(LogOp n)

Erases 'NOT' operand from the logical expression n by flipping the right children

Parameters:

n - a logical expression

merge

public static void merge(LogOp.Operator op,
                         LogOp n)

Flattens a logical expression n based on operator op. Transform from undefined depth expression to comb expression

Parameters:

op - reference operator

n - the lofical expression

developOr

public static LogOp developOr(LogOp n)

Moves down 'OR' operand in the logical expression n.

Parameters:

n - a logical expression

Returns:

the modified logical expression

distribute

public static LogOp distribute(LogOp n)

Distributes 'OR's inwards over 'AND's in n

Parameters:

n - a logical expression

Returns:

the modified logical expression

simplify

public static ILogical simplify(ILogical t,
                                Model model)

Detects tautologies and contradictions from t

Parameters:

t - a logical expression

model - to get IVariableFactory.boolVar(boolean).

Returns:

simplified logical expression

simplifySingleton

public static ILogical simplifySingleton(ILogical l,
                                         Model model)

Remove tautologies from l

Parameters:

l - logical expression

model - to get IVariableFactory.intVar(int).

Returns:

simplified logical expression