public bool EmptinessSearch(GeneralizedBuchiAutomaton<AutomatonNode> a, AutomatonNode qi)
{
label = new Dictionary<AutomatonNode, HashSet<int>> ();
foreach (var n in a.Nodes) {
label.Add (n, new HashSet<int> ());
}
//for (int i = 0, length = a.Transitions.Count; i < length; i++) {
// label[i] = new HashSet<int> ();
//}
path.Push (qi);
while (path.Count > 0) {
var q = path.Peek ();
//Console.WriteLine ("q={0}", q.Name);
var succToProcess = a.Post(q).Except (path.Union (processed));
while (succToProcess.Count () > 0) {
var succ = succToProcess.First ();
path.Push (succ);
label [succ] = new HashSet<int> ();
q = succ;
succToProcess = a.Post(q).Except (path.Union (processed));
//Console.WriteLine ("q={0}", q.Name);
}
//Console.WriteLine ("----");
if (label[q].Count == 0 | a.AcceptanceCondition.Accept(q)) { // a.AcceptanceSets.Any (x => x.Nodes.Contains (q))
var labelsToPropagate = label [q].Union (a.AcceptanceCondition.GetAcceptingConditions(q));
//Console.WriteLine ("labelsToPropagate={0}", string.Join (",", labelsToPropagate));
propagate (a, new [] { q }, labelsToPropagate);
if (label[q].SetEquals (a.AcceptanceCondition.AllKeys ())) {
goto ExitTrue;
// return true;
}
}
processed.Add (q);
path.Pop ();
}
return false;
ExitTrue : return true;
}
void propagate(GeneralizedBuchiAutomaton<AutomatonNode> a, IEnumerable<AutomatonNode> nodes, IEnumerable<int> labelsToPropagate)
{
//Console.WriteLine ("path : " + string.Join(",", path));
//Console.WriteLine ("processed : " + string.Join(",", processed));
var toProp = labelsToPropagate.ToArray ();
var nodesToProcess = new Stack<AutomatonNode> (nodes);
while (nodesToProcess.Count > 0) {
var q = nodesToProcess.Pop ();
var successors = a.Post(q).Intersect (path.Union (processed));
//Console.WriteLine ("successors : " + string.Join(",", a.OutEdges (q).Select (x => x.Target.Name)));
//Console.WriteLine ("successors : " + string.Join(",", successors));
foreach (var succ in successors) {
if (!label[succ].IsSupersetOf (labelsToPropagate)) {
nodesToProcess.Push (succ);
for (int i = 0, toPropLength = toProp.Length; i < toPropLength; i++) {
label [succ].Add (toProp [i]);
}
}
}
}
}