org.sat4j.core
Class LiteralsUtils

java.lang.Object
  org.sat4j.core.LiteralsUtils

public final class LiteralsUtils
extends java.lang.Object

Utility methods to avoid using bit manipulation inside code. One should use Java 1.5 import static feature to use it without class qualification inside the code. In the DIMACS format, the literals are represented by signed integers, 0 denoting the end of the clause. In the solver, the literals are represented by positive integers, in order to use them as index in arrays for instance.

  int p : a literal (p>1)
  p ˆ 1 : the negation of the literal
  p >> 1 : the DIMACS number reresenting the variable.
  int v : a DIMACS variable (v>0)
  v << 1 : a positive literal for that variable in the solver.
  v << 1 ˆ 1 : a negative literal for that variable. 
 

Author:

leberre

Method Summary

static int	neg(int p) Returns the opposite literal.
static int	negLit(int var) Returns the negative literal associated with a variable.
static int	posLit(int var) Returns the positive literal associated with a variable.
static int	toDimacs(int p) decode the internal representation of a literal into Dimacs format.
static int	var(int p) Returns the variable associated to the literal

Methods inherited from class java.lang.Object

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

Method Detail

var

public static int var(int p)

Returns the variable associated to the literal

Parameters:

p - a literal

Returns:

the variable associated to that literal.

neg

public static int neg(int p)

Returns the opposite literal.

Parameters:

p - a literal

Returns:

the opposite literal

posLit

public static int posLit(int var)

Returns the positive literal associated with a variable.

Parameters:

var - a variable

Returns:

the positive literal associated to this variable.

negLit

public static int negLit(int var)

Returns the negative literal associated with a variable.

Parameters:

var - a variable.

Returns:

the negative literal associated with var.

toDimacs

public static int toDimacs(int p)

decode the internal representation of a literal into Dimacs format.

Parameters:

p - the literal in internal representation

Returns:

the literal in dimacs representation