CSP for Java

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Julien Vion — 2009-05-06T11:22:43Z

CSP4J

Julien Vion — 2009-05-06T11:46:54Z

CSP4J is a CSP solving API. It is designed to solve quickly and easily combinatorial problems that are parts of Java applications.

Example code for solving the n-queens problem:

public class Queens implements ProblemGenerator {
 private final int size;
 private final Collection<Constraint> constraints;
 private final List<Variable> variables;
 public Queens(int size) {
 this.size = size;
 constraints = new ArrayList<Constraint>();
 variables = new ArrayList<Variable>();
 }
 @Override
 public void generate() {
 final int[] domain = new int[size];
 for (int i = 0; i < size; i++) {
 domain[i] = i;
 }
 for (int i = 0; i < size; i++) {
 variables.add(new Variable(domain));
 }
 for (int i = 0; i < size; i++) {
 for (int j = i + 1; j < size; j++) {
 final int diff = Math.abs(i - j);
 constraints.add(new AbstractAC3Constraint(variables
 .get(i), variables.get(j)) {
 @Override
 public boolean check() {
 return getValue(0) != getValue(1)
 && Math
 .abs(getValue(0)
 - getValue(1)) != diff;
 }
 });
 }
 }
 }
 @Override
 public Collection<Constraint> getConstraints() {
 return constraints;
 }
 @Override
 public List<Variable> getVariables() {
 return variables;
 }
 public static void main(String[] args)
 throws FailedGenerationException, IOException {
 final ProblemGenerator generator = new Queens(Integer
 .valueOf(args[0]));
 final Solver solver = new MGACIter(Problem.load(generator));
 solver.runSolver();
 for (Variable v : generator.getVariables()) {
 System.out
 .println(v + ": " + solver.getSolution().get(v));
 }
 }
}

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CSPOM

Julien Vion — 2009-05-05T17:48:00Z

The CSP Object Model is a CP Modelling API, compatible with the XCSP 2.0 language.

Example modelling the n-queens problem :

final cspom.Problem problem = new cspom.Problem("Queens");
final Domain domain = new IntervalDomain("", 0, size - 1);
for (int i = 0; i < size; i++) {
 problem.addVariable(new cspom.variable.Variable("Q" + i, domain));
}
final Predicate predicate = new Predicate("", "int X int Y int diff",
 "X!=Y && abs(X-Y)!=diff");
for (int i = 0; i < size; i++) {
 for (int j = i + 1; j < size; j++) {
 final int diff = Math.abs(i - j);
 problem.addConstraint(new PredicateConstraint("C" + i + j, "Q"
 + i + " Q" + j + " " + diff, predicate, problem
 .getVariables().get(i), problem.getVariables().get(j)));
 }
}

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Or loading from XCSP format :

final cspom.Problem problem = new CspOM.load("queens-120.xml");

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Julien Vion — 2009-05-25T13:01:17Z

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Julien Vion — 2009-05-25T13:03:36Z

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Julien Vion — 2009-05-25T13:04:43Z

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