/**
* For efficiency reasons the queue manages updated variables vj whereas the original AC3
* manages neighbor arcs (vi, vj). Constraints which are not binary are ignored.
*/
private void reduceDomains(ICollection <VAR> queue, CSP <VAR, VAL> csp, DomainLog <VAR, VAL> log)
{
while (!queue.IsEmpty())
{
VAR var = queue.Pop();
foreach (IConstraint <VAR, VAL> constraint in csp.getConstraints(var))
{
VAR neighbor = csp.getNeighbor(var, constraint);
if (neighbor != null && revise(neighbor, var, constraint, csp, log))
{
if (csp.getDomain(neighbor).isEmpty())
{
log.setEmptyDomainFound(true);
return;
}
queue.Add(neighbor);
}
}
}
}
/**
* Removes all values from the domains of the neighbor variables of <code>var</code> in the
* constraint graph which are not consistent with the new value for <code>var</code>.
* It is called after <code>assignment</code> has (recursively) been extended with a value
* assignment for <code>var</code>.
*/
public IInferenceLog <VAR, VAL> apply(CSP <VAR, VAL> csp, Assignment <VAR, VAL> assignment, VAR var)
{
DomainLog <VAR, VAL> log = new DomainLog <VAR, VAL>();
foreach (IConstraint <VAR, VAL> constraint in csp.getConstraints(var))
{
VAR neighbor = csp.getNeighbor(var, constraint);
if (neighbor != null && !assignment.contains(neighbor))
{
if (revise(neighbor, constraint, assignment, csp, log))
{
if (csp.getDomain(neighbor).isEmpty())
{
log.setEmptyDomainFound(true);
return(log);
}
}
}
}
return(log);
}
