/// <summary>
/// Forward search, check destination is reachable from source
/// NOT store all reachable states, use some special condition to terminate
/// At step t, find all reachable states after t time units
/// Fix point when rechable(t1 + a, t1 + a) is a subset of rechable(t1, t1)
/// Rabbit algorithm (S x Tick x Trans*)*
/// [ REFS: '', DEREFS:]
/// </summary>
/// <param name="source"></param>
/// <param name="destination"></param>
/// <param name="discreteTransitions"></param>
/// <returns></returns>
public bool PathForward2(CUDDNode source, CUDDNode destination, List <CUDDNode> discreteTransitions, List <CUDDNode> tickTransitions)
{
//
bool reachable = false;
CUDD.Ref(source);
CUDDNode currentReachableFromInit = SuccessorsStart(source, discreteTransitions);
CUDDNode previousReachableFromInit = CUDD.Constant(0);
int s, p;
s = p = 0;
CUDDNode commonNode = CUDD.Constant(0);
int numberOfLoop = 0;
while (!CUDD.IsSubSet(previousReachableFromInit, currentReachableFromInit))
{
numberOfLoop++;
Debug.Write(numberOfLoop + " ");
if (p <= s / 2)
{
p = s;
CUDD.Deref(previousReachableFromInit);
CUDD.Ref(currentReachableFromInit);
previousReachableFromInit = currentReachableFromInit;
}
currentReachableFromInit = Successors(currentReachableFromInit, tickTransitions);
currentReachableFromInit = SuccessorsStart(currentReachableFromInit, discreteTransitions);
s++;
//Check 2 directions have intersection
CUDD.Ref(destination, currentReachableFromInit);
CUDD.Deref(commonNode);
commonNode = CUDD.Function.And(destination, currentReachableFromInit);
if (!commonNode.Equals(CUDD.ZERO))
{
reachable = true;
break;
}
}
Debug.WriteLine("\nTA Path Forward 2: " + numberOfLoop + " loops.");
CUDD.Deref(currentReachableFromInit, previousReachableFromInit, commonNode);
//
return(reachable);
}