Title: On the top-down evaluation of tree inclusion problem

Authors: Yangjun Chen, Yibin Chen

Addresses: Department of Applied Computer Science, University of Winnipeg, Winnipeg, Manitoba, R3B 2E9, Canada. ' Department of Applied Computer Science, University of Winnipeg, Winnipeg, Manitoba, R3B 2E9, Canada

Abstract: We consider the following tree-matching problem: Given labelled, ordered trees P and T, can P be obtained from T by deleting nodes. Deleting a node v entails removing all edges incident to v and, if v has a parent u, replacing the edges from u to v by edges from u to the children of v. The best known algorithm for this problem needs O(|T|•|leaves(P)|) time and O(|leaves(P)|•min{DT•|leaves(T)|} + |T| + |P|) space, where leaves(T) (resp. leaves(P)) stands for the set of the leaves of T (resp. P), and DT(resp. DP) for the height of T (resp. P). In this paper, we present a new algorithm that requires O(|T|•|leaves(P)|) time but only O(|T| + |P|) space.

Keywords: ordered labelled trees; tree inclusion; TreeBank; tree matching problem.

DOI: 10.1504/IJITCC.2011.042124

International Journal of Information Technology, Communications and Convergence, 2011 Vol.1 No.3, pp.238 - 253

Published online: 28 Aug 2011 *

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