public void Add(InferenceResults <Tval> inferenceToAdd)
{
isConsistent = isConsistent && inferenceToAdd.isConsistent;
foreach (var item in inferenceToAdd.storedDomains)
{
if (storedDomains.TryGetValue(item.Key, out var domain))
{
domain.GetValues().UnionWith(item.Value.GetValues());
}
else
{
storedDomains.Add(item.Key, item.Value);
}
}
variablesWithEmptyDomain.AddRange(inferenceToAdd.variablesWithEmptyDomain);
}
// It might be possible to parallelize this method
// giving to each task a different value of X
// but I'm not sure if it's worth it or if it creates problem with
// the paralelized IsConsistent check.
private async Task <bool> Revise(ConstraintSatisfactionProblem <Tval> csp, Variable <Tval> variableX, Variable <Tval> variableY, InferenceResults <Tval> inference)
{
bool revised = false;
Assignment <Tval> assignment = new Assignment <Tval>();
Domain <Tval> oldDomain = new Domain <Tval>(variableX.GetDomain());
List <Tval> domain_values = new List <Tval>(oldDomain.GetValues());
foreach (Tval valueX in domain_values)
{
assignment.Assign(variableX, valueX);
bool satisfiable = true;
foreach (Tval valueY in variableY.GetDomain().GetValues())
{
satisfiable = false;
assignment.Assign(variableY, valueY);
bool isConsistent = assignment.IsConsistent(csp.GetAllDiffConstraints());
if (isConsistent)
{
satisfiable = true;
break;
}
}
if (!satisfiable)
{
variableX.GetDomain().RemoveValue(valueX);
revised = true;
}
}
if (revised)
{
inference.StoreDomainForVariable(variableX, oldDomain);
}
return(revised);
}
private async Task <InferenceResults <Tval> > ReduceDomains(ConstraintSatisfactionProblem <Tval> csp, Queue <Tuple <Variable <Tval>, Variable <Tval> > > queueOfArcs, InferenceResults <Tval> inference = null, bool stopAtInconsistency = true)
{
inference = inference ?? new InferenceResults <Tval>();
while (queueOfArcs.Count > 0)
{
Tuple <Variable <Tval>, Variable <Tval> > arc = queueOfArcs.Dequeue();
Variable <Tval> X = arc.Item1, Y = arc.Item2;
if (await Revise(csp, X, Y, inference))
{
if (X.GetDomain().Size() == 0)
{
inference.InconsistencyFound(X);
if (stopAtInconsistency)
{
return(inference);
}
}
foreach (Variable <Tval> neighbour in csp.GetNeighboursOf(X))
{
queueOfArcs.Enqueue(new Tuple <Variable <Tval>, Variable <Tval> >(neighbour, X));
}
}
}
return(inference);
}
public override async Task <InferenceResults <Tval> > Infer(ConstraintSatisfactionProblem <Tval> csp, Variable <Tval> variable, Tval value, InferenceResults <Tval> inference = null, bool stopAtInconsistency = true)
{
Queue <Tuple <Variable <Tval>, Variable <Tval> > > queueOfArcs = new Queue <Tuple <Variable <Tval>, Variable <Tval> > >((variable != null) ? csp.GetArcsTowards(variable) : csp.GetArcs());
return(await ReduceDomains(csp, queueOfArcs, inference, stopAtInconsistency));
}
abstract public Task <InferenceResults <Tval> > Infer(ConstraintSatisfactionProblem <Tval> csp, Variable <Tval> variable, Tval value, InferenceResults <Tval> inference = null, bool stopAtInconsistency = true);