private bool revise(Variable xi, Variable xj, Constraint constraint, CSP csp, DomainRestoreInfo info) { bool revised = false; Assignment assignment = new Assignment(); foreach (Object iValue in csp.getDomain(xi)) { assignment.setAssignment(xi, iValue); bool consistentExtensionFound = false; foreach (Object jValue in csp.getDomain(xj)) { assignment.setAssignment(xj, jValue); if (constraint.isSatisfiedWith(assignment)) { consistentExtensionFound = true; break; } } if (!consistentExtensionFound) { info.storeDomainFor(xi, csp.getDomain(xi)); csp.removeValueFromDomain(xi, iValue); revised = true; } } return(revised); }
private Object getMinConflictValueFor(Variable var, Assignment assignment, CSP csp) { List <Constraint> constraints = csp.getConstraints(var); Assignment duplicate = assignment.copy(); int minConflict = int.MAX_VALUE; List <Object> resultCandidates = new List <Object>(); foreach (Object value in csp.getDomain(var)) { duplicate.setAssignment(var, value); int currConflict = countConflicts(duplicate, constraints); if (currConflict <= minConflict) { if (currConflict < minConflict) { resultCandidates.clear(); minConflict = currConflict; } resultCandidates.Add(value); } } if (!resultCandidates.isEmpty()) { return(Util.selectRandomlyFromList(resultCandidates)); } else { return(null); } }
/** : the degree heuristic. */ private List <Variable> applyDegreeHeuristic(List <Variable> vars, Assignment assignment, CSP csp) { List <Variable> result = new List <Variable>(); int maxDegree = int.MIN_VALUE; foreach (Variable var in vars) { int degree = 0; foreach (Constraint constraint in csp.getConstraints(var)) { Variable neighbor = csp.getNeighbor(var, constraint); if (!assignment.hasAssignmentFor(neighbor) && csp.getDomain(neighbor).Count > 1) { ++degree; } } if (degree >= maxDegree) { if (degree > maxDegree) { result.clear(); maxDegree = degree; } result.Add(var); } } return(result); }
// ////////////////////////////////////////////////////////////// // inference algorithms /** : forward checking. */ private DomainRestoreInfo doForwardChecking(Variable var, Assignment assignment, CSP csp) { DomainRestoreInfo result = new DomainRestoreInfo(); foreach (Constraint constraint in csp.getConstraints(var)) { List <Variable> scope = constraint.getScope(); if (scope.Count == 2) { foreach (Variable neighbor in constraint.getScope()) { if (!assignment.hasAssignmentFor(neighbor)) { if (revise(neighbor, constraint, assignment, csp, result)) { if (csp.getDomain(neighbor).isEmpty()) { result.setEmptyDomainFound(true); return(result); } } } } } } return(result); }
/** : the least constraining value heuristic. */ private List <Object> applyLeastConstrainingValueHeuristic(Variable var, CSP csp) { List <Pair <Object, int> > pairs = new List <Pair <Object, int> >(); foreach (Object value in csp.getDomain(var)) { int num = countLostValues(var, value, csp); pairs.Add(new Pair <Object, int>(value, num)); } // TODO //Collections.sort(pairs, new Comparator<Pair<Object, int>>() { // public int compare(Pair<Object, int> o1, // Pair<Object, int> o2) { // return o1.getSecond() < o2.getSecond() ? -1 // : o1.getSecond() > o2.getSecond() ? 1 : 0; // } //}); List <Object> result = new List <Object>(); foreach (Pair <Object, int> pair in pairs) { result.Add(pair.getFirst()); } return(result); }
private bool revise(Variable var, Constraint constraint, Assignment assignment, CSP csp, DomainRestoreInfo info) { bool revised = false; foreach (Object value in csp.getDomain(var)) { assignment.setAssignment(var, value); if (!constraint.isSatisfiedWith(assignment)) { info.storeDomainFor(var, csp.getDomain(var)); csp.removeValueFromDomain(var, value); revised = true; } assignment.removeAssignment(var); } return(revised); }
private Assignment generateRandomAssignment(CSP csp) { Assignment assignment = new Assignment(); foreach (Variable var in csp.getVariables()) { Object randomValue = Util.selectRandomlyFromList(csp.getDomain(var) .asList()); assignment.setAssignment(var, randomValue); } return assignment; }
/** * Primitive operation, ordering the domain values of the specified * variable. */ protected override Iterable?orderDomainValues(Variable var, Assignment assignment, CSP csp) { if (!isLCVHeuristicEnabled) { return(csp.getDomain(var)); } else { return(applyLeastConstrainingValueHeuristic(var, csp)); } }
private Assignment generateRandomAssignment(CSP csp) { Assignment assignment = new Assignment(); foreach (Variable var in csp.getVariables()) { Object randomValue = Util.selectRandomlyFromList(csp.getDomain(var) .asList()); assignment.setAssignment(var, randomValue); } return(assignment); }
private int countLostValues(Variable var, Object value, CSP csp) { int result = 0; Assignment assignment = new Assignment(); assignment.setAssignment(var, value); foreach (Constraint constraint in csp.getConstraints(var)) { Variable neighbor = csp.getNeighbor(var, constraint); foreach (Object nValue in csp.getDomain(neighbor)) { assignment.setAssignment(neighbor, nValue); if (!constraint.isSatisfiedWith(assignment)) { ++result; } } } return(result); }
/** * Reduces the domain of the specified variable to the specified * value and reestablishes arc-consistency. It is assumed that the * provided CSP is arc-consistent before the call. * @return An object which indicates success/failure and contains * data to undo the operation. */ public DomainRestoreInfo reduceDomains(Variable var, Object value, CSP csp) { DomainRestoreInfo result = new DomainRestoreInfo(); Domain domain = csp.getDomain(var); if (domain.contains(value)) { if (domain.Count > 1) { FIFOQueue<Variable> queue = new FIFOQueue<Variable>(); queue.Add(var); result.storeDomainFor(var, domain); csp.setDomain(var, new Domain(new Object[] { value })); reduceDomains(queue, csp, result); } } else { result.setEmptyDomainFound(true); } return result.compactify(); }
/** * Reduces the domain of the specified variable to the specified * value and reestablishes arc-consistency. It is assumed that the * provided CSP is arc-consistent before the call. * @return An object which indicates success/failure and contains * data to undo the operation. */ public DomainRestoreInfo reduceDomains(Variable var, Object value, CSP csp) { DomainRestoreInfo result = new DomainRestoreInfo(); Domain domain = csp.getDomain(var); if (domain.contains(value)) { if (domain.Count > 1) { FIFOQueue <Variable> queue = new FIFOQueue <Variable>(); queue.Add(var); result.storeDomainFor(var, domain); csp.setDomain(var, new Domain(new Object[] { value })); reduceDomains(queue, csp, result); } } else { result.setEmptyDomainFound(true); } return(result.compactify()); }
// ////////////////////////////////////////////////////////////// // heuristics for selecting the next unassigned variable and domain ordering /** : the minimum-remaining-values heuristic. */ private List <Variable> applyMRVHeuristic(CSP csp, Assignment assignment) { List <Variable> result = new List <Variable>(); int mrv = int.MAX_VALUE; foreach (Variable var in csp.getVariables()) { if (!assignment.hasAssignmentFor(var)) { int num = csp.getDomain(var).Count; if (num <= mrv) { if (num < mrv) { result.clear(); mrv = num; } result.Add(var); } } } return(result); }
private void reduceDomains(FIFOQueue <Variable> queue, CSP csp, DomainRestoreInfo info) { while (!queue.isEmpty()) { Variable var = queue.pop(); foreach (Constraint constraint in csp.getConstraints(var)) { if (constraint.getScope().Count == 2) { Variable neighbor = csp.getNeighbor(var, constraint); if (revise(neighbor, var, constraint, csp, info)) { if (csp.getDomain(neighbor).isEmpty()) { info.setEmptyDomainFound(true); return; } queue.push(neighbor); } } } } }
private void reduceDomains(FIFOQueue<Variable> queue, CSP csp, DomainRestoreInfo info) { while (!queue.isEmpty()) { Variable var = queue.pop(); foreach (Constraint constraint in csp.getConstraints(var)) { if (constraint.getScope().Count == 2) { Variable neighbor = csp.getNeighbor(var, constraint); if (revise(neighbor, var, constraint, csp, info)) { if (csp.getDomain(neighbor).isEmpty()) { info.setEmptyDomainFound(true); return; } queue.push(neighbor); } } } } }
/** : the least constraining value heuristic. */ private List<Object> applyLeastConstrainingValueHeuristic(Variable var, CSP csp) { List<Pair<Object, int>> pairs = new List<Pair<Object, int>>(); foreach (Object value in csp.getDomain(var)) { int num = countLostValues(var, value, csp); pairs.Add(new Pair<Object, int>(value, num)); } // TODO //Collections.sort(pairs, new Comparator<Pair<Object, int>>() { // public int compare(Pair<Object, int> o1, // Pair<Object, int> o2) { // return o1.getSecond() < o2.getSecond() ? -1 // : o1.getSecond() > o2.getSecond() ? 1 : 0; // } //}); List<Object> result = new List<Object>(); foreach (Pair<Object, int> pair in pairs) result.Add(pair.getFirst()); return result; }
/** : the degree heuristic. */ private List<Variable> applyDegreeHeuristic(List<Variable> vars, Assignment assignment, CSP csp) { List<Variable> result = new List<Variable>(); int maxDegree = int.MIN_VALUE; foreach (Variable var in vars) { int degree = 0; foreach (Constraint constraint in csp.getConstraints(var)) { Variable neighbor = csp.getNeighbor(var, constraint); if (!assignment.hasAssignmentFor(neighbor) && csp.getDomain(neighbor).Count > 1) ++degree; } if (degree >= maxDegree) { if (degree > maxDegree) { result.clear(); maxDegree = degree; } result.Add(var); } } return result; }
// ////////////////////////////////////////////////////////////// // inference algorithms /** : forward checking. */ private DomainRestoreInfo doForwardChecking(Variable var, Assignment assignment, CSP csp) { DomainRestoreInfo result = new DomainRestoreInfo(); foreach (Constraint constraint in csp.getConstraints(var)) { List<Variable> scope = constraint.getScope(); if (scope.Count == 2) { foreach (Variable neighbor in constraint.getScope()) { if (!assignment.hasAssignmentFor(neighbor)) { if (revise(neighbor, constraint, assignment, csp, result)) { if (csp.getDomain(neighbor).isEmpty()) { result.setEmptyDomainFound(true); return result; } } } } } } return result; }
private int countLostValues(Variable var, Object value, CSP csp) { int result = 0; Assignment assignment = new Assignment(); assignment.setAssignment(var, value); foreach (Constraint constraint in csp.getConstraints(var)) { Variable neighbor = csp.getNeighbor(var, constraint); foreach (Object nValue in csp.getDomain(neighbor)) { assignment.setAssignment(neighbor, nValue); if (!constraint.isSatisfiedWith(assignment)) { ++result; } } } return result; }
/** * Primitive operation, ordering the domain values of the specified * variable. */ protected override Iterable? orderDomainValues(Variable var, Assignment assignment, CSP csp) { if (!isLCVHeuristicEnabled) { return csp.getDomain(var); } else { return applyLeastConstrainingValueHeuristic(var, csp); } }
private bool revise(Variable var, Constraint constraint, Assignment assignment, CSP csp, DomainRestoreInfo info) { bool revised = false; foreach (Object value in csp.getDomain(var)) { assignment.setAssignment(var, value); if (!constraint.isSatisfiedWith(assignment)) { info.storeDomainFor(var, csp.getDomain(var)); csp.removeValueFromDomain(var, value); revised = true; } assignment.removeAssignment(var); } return revised; }
/** * Primitive operation, ordering the domain values of the specified * variable. This default implementation just takes the default order * provided by the CSP. */ protected Iterable? orderDomainValues(Variable var, Assignment assignment, CSP csp) { return csp.getDomain(var); }
/** * Primitive operation, ordering the domain values of the specified * variable. This default implementation just takes the default order * provided by the CSP. */ protected Iterable?orderDomainValues(Variable var, Assignment assignment, CSP csp) { return(csp.getDomain(var)); }
private Object getMinConflictValueFor(Variable var, Assignment assignment, CSP csp) { List<Constraint> constraints = csp.getConstraints(var); Assignment duplicate = assignment.copy(); int minConflict = int.MAX_VALUE; List<Object> resultCandidates = new List<Object>(); foreach (Object value in csp.getDomain(var)) { duplicate.setAssignment(var, value); int currConflict = countConflicts(duplicate, constraints); if (currConflict <= minConflict) { if (currConflict < minConflict) { resultCandidates.clear(); minConflict = currConflict; } resultCandidates.Add(value); } } if (!resultCandidates.isEmpty()) return Util.selectRandomlyFromList(resultCandidates); else return null; }
private bool revise(Variable xi, Variable xj, Constraint constraint, CSP csp, DomainRestoreInfo info) { bool revised = false; Assignment assignment = new Assignment(); foreach (Object iValue in csp.getDomain(xi)) { assignment.setAssignment(xi, iValue); bool consistentExtensionFound = false; foreach (Object jValue in csp.getDomain(xj)) { assignment.setAssignment(xj, jValue); if (constraint.isSatisfiedWith(assignment)) { consistentExtensionFound = true; break; } } if (!consistentExtensionFound) { info.storeDomainFor(xi, csp.getDomain(xi)); csp.removeValueFromDomain(xi, iValue); revised = true; } } return revised; }
// ////////////////////////////////////////////////////////////// // heuristics for selecting the next unassigned variable and domain ordering /** : the minimum-remaining-values heuristic. */ private List<Variable> applyMRVHeuristic(CSP csp, Assignment assignment) { List<Variable> result = new List<Variable>(); int mrv = int.MAX_VALUE; foreach (Variable var in csp.getVariables()) { if (!assignment.hasAssignmentFor(var)) { int num = csp.getDomain(var).Count; if (num <= mrv) { if (num < mrv) { result.clear(); mrv = num; } result.Add(var); } } } return result; }