Constant Time Enumeration of Bounded-Size Subtrees in Trees and Its Application

摘要

By the motivation to discover patterns in massive structured data in the form of graphs and trees, we study a special case of the k-subtree enumeration problem, originally introduced by (Ferreira, Grossi, and Rizzi, ESA'11, 275-286, 2011), where an input graph is a tree of n nodes. Based on reverse search technique, we present the first constant delay enumeration algorithm that lists all k-subtrees of an input tree in O(1) worst-case time per subtree. This result improves on the straightforward application of Ferreira et al's algorithm with O(k) amortized time per subtree when an input is restricted to tree. Finally, we discuss an application of our algorithm to a modification of the graph motif problem for trees.