In wandering, D is mere one of vertices in a graph while D is the vertex at which movements terminate, is also called destination. An adjacent vertex is a vertex that is linked to another vertices. For example, adjacent vertices of S are A and B , and A is also an adjacent vertex to S as well as B and D . A S-D path is a sequence of vertices beginning with S and ending with D that a virus visits during a trip from S to D without visiting any node that has already been visited. Each path has its own weight that indicates grade of a path.
Some path has higher weight than other paths.
It means that a virus that makes a trip along the lower weight path has the higher probability of accomplishing the trip than the trip along the higher weight paths. The best path is a path that has the lowest weight or the least chance of detecting viruses, so it provides viruses the highest probability of accomplishing trips. When there is more than one path providing an equal highest or lowest probability of detection, one is still arbitrarily chosen as the best or the worst path. In theoretical discuss, all paths and their weights are knowable in assumption, however, in real world such information may not be easily available. In the worst case, no paths and none of their weights are known, then cruise can not make judgment.