דקל צור

We study the subtree isomorphism problem: Given trees H and G, find a subtree of G which is isomorphic to H or decide that there is no such subtree. We give an O(k^1.5/log k n)-time algorithm for this problem, where k and n are the number of vertices in H and G respectively. This improves over the O(k^1.5n) algorithms of Chung and Matula. We also give a randomized (Las Vegas) O(min(k^1.45n, kn^1.43))-time algorithm for the decision problem.