/// <summary>
/// Find the deadlock state. This state can be reached by a terminate event.
/// Later termination transition is removed from the transition to finding path
/// [ REFS: , DEREFS: ]
/// </summary>
/// <param name="transitions"></param>
/// <param name="model"></param>
/// <returns></returns>
public static CUDDNode GetDeadlockDD(List<CUDDNode> transitions, Model model)
{
CUDDNode result = CUDD.Constant(1);
//result contains state not having not tick outgoing transition
foreach (CUDDNode transition in transitions)
{
CUDD.Ref(transition);
CUDDNode notTickTrans = CUDD.Function.And(transition, CUDD.Function.Not(TimeBehaviors.GetTickTransEncoding(model)));
//having not tick outgoing transition
CUDDNode notDeadlockState = CUDD.Abstract.ThereExists(notTickTrans, model.AllColVars);
CUDDNode deadlockState = CUDD.Function.Not(notDeadlockState);
result = CUDD.Function.And(result, deadlockState);
}
CUDD.Ref(transitions);
List<CUDDNode> tickTrans = CUDD.Function.And(transitions, TimeBehaviors.GetTickTransEncoding(model));
CUDD.Ref(tickTrans);
CUDDNode stateHasTickTrans = CUDD.Function.Or(CUDD.Abstract.ThereExists(tickTrans, model.AllColVars));
List<int> eventIndex = model.GetEventIndex();
for (int i = 0; i < model.GetNumberOfVars(); i++)
{
if(!eventIndex.Contains(i))
{
CUDD.Ref(model.varIdentities[i]);
tickTrans = CUDD.Function.And(tickTrans, model.varIdentities[i]);
}
}
CUDDNode stateHasLoopTick = CUDD.Function.Or(CUDD.Abstract.ThereExists(tickTrans, model.AllColVars));
//Deadlock state: not having not tick transition and if has tick, then it must loop tick
CUDD.Ref(result);
result = CUDD.Function.Or(CUDD.Function.And(result, CUDD.Function.Not(stateHasTickTrans)), CUDD.Function.And(result, stateHasLoopTick));
return result;
}
