techniques.PL
Class CNF

java.lang.Object
  |
  +--techniques.PL.CNF

public final class CNF

extends java.lang.Object

A set of utilities for dealing with propositional logic sentences in conjunctive normal form (CNF).

Constructor Summary

CNF()

 

Method Summary
static boolean	coinFlip()           Returns true with probability 0.5.
static void	main(java.lang.String[] args)           A command-line accessible version of the randInstance() method.
static Conjunction	parse(java.io.File infile)           Parses a textfile into a Conjunction.
static Conjunction	parse(java.lang.String sentence)           Parses a String into a Conjunction.
static java.lang.String	pl2dimacs(java.io.File cnfFile)           Given a file containing a CNF sentence, this function outputs the same sentence, in DIMACS format, to a file.
static java.lang.String	pl2dimacs(java.io.File cnfFile, java.lang.String dimacsFile)           Given a file containing a CNF sentence,this function outputs the same sentence, in DIMACS format, to a file.
static java.lang.String	pl2dimacs(Sentence cnfSentence, java.lang.String dimacsFile)           Given a CNF sentence,this function outputs the same sentence, in DIMACS format, to a file.
static java.lang.String	randDisjunction()           Returns a disjunction of three literals chosen by randLiteral()
static java.lang.String	randInstance(int numClauses)           Returns a randomly generated 3-SAT instance, as a String.
static int	randInt(int a, int b)           returns a random integer between a and b, inclusive.
static java.lang.String	randLiteral()           Returns a random literal, as a string.
static Interpretation	zchaffToInterpretation(java.lang.String zchaffOutputFile, java.lang.String mapFile)           Given the a fileName containing the standard output of a zChaff invocation, and the fileName of the mapFile generated by CNF.pl2dimacs(), create an Interpretation that maps PL.Variables (as specified in the mapFile) to the assignments reported by zChaff.

 

Methods inherited from class java.lang.Object

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

 

Constructor Detail

CNF

public CNF()

parse

public static Conjunction parse(java.lang.String sentence)

Parses a String into a Conjunction. This Parser does very little error checking. Unparsable sentences will either produce garbage or a runtime Exception. Whitespace is insignificant.

parse

public static Conjunction parse(java.io.File infile)

Parses a textfile into a Conjunction. If there is an IO Error, this method will print an error message and returns null. Otherwise, this Parser does very little error checking. Unparsable sentences will either produce garbage or a runtime Exception. Whitespace in the file is insignificant.

pl2dimacs

public static java.lang.String pl2dimacs(java.io.File cnfFile)

Given a file containing a CNF sentence, this function outputs the same sentence, in DIMACS format, to a file. Also, produces a file containing a map of the original Variable names to the new DIMACS names.

pl2dimacs

public static java.lang.String pl2dimacs(java.io.File cnfFile,
                                         java.lang.String dimacsFile)

Given a file containing a CNF sentence,this function outputs the same sentence, in DIMACS format, to a file. Also, produces a file containing a map of the original Variable names to the new DIMACS names.

pl2dimacs

public static java.lang.String pl2dimacs(Sentence cnfSentence,
                                         java.lang.String dimacsFile)

Given a CNF sentence,this function outputs the same sentence, in DIMACS format, to a file. Also, produces a file containing a map of the original Variable names to the new DIMACS names.

zchaffToInterpretation

public static Interpretation zchaffToInterpretation(java.lang.String zchaffOutputFile,
                                                    java.lang.String mapFile)

Given the a fileName containing the standard output of a zChaff invocation, and the fileName of the mapFile generated by CNF.pl2dimacs(), create an Interpretation that maps PL.Variables (as specified in the mapFile) to the assignments reported by zChaff.

main

public static void main(java.lang.String[] args)

A command-line accessible version of the randInstance() method. It takes one mandatory and one optional argument. The first argument is a real number indicating the ratio of clauses to variables in the returned instance. The second (optional) argument is a filename in which to write the results. If no second argument is supplied, the sentence will be sent to standard out.

For example:

% java techniques.PL.CNF 2.2 mysentence.cnf

will result in a sentence with 57 clauses (about 2.2*26), written to a file named mysentence.cnf.

randInstance

public static java.lang.String randInstance(int numClauses)

Returns a randomly generated 3-SAT instance, as a String. All sentences are drawn from a world of 26 variables, A-Z. numClauses is the number of disjunctive clauses to generate.

randDisjunction

public static java.lang.String randDisjunction()

Returns a disjunction of three literals chosen by randLiteral()

randLiteral

public static java.lang.String randLiteral()

Returns a random literal, as a string. The variable of the literal is drawn uniformly from 'A'-'Z', and negated with probability 0.5.

coinFlip

public static boolean coinFlip()

Returns true with probability 0.5.

randInt

public static int randInt(int a,
                          int b)

returns a random integer between a and b, inclusive.