Efficient Algorithms for the Tree Homeomorphism Problem

Tree pattern matching is a fundamental problem that has a wide range of applications in Web data management, XML processing, and selective data dissemination. In this paper we develop efficient algorithms for the tree homeomorphism problem, i.e., the problem of matching a tree pattern with exclusively transitive (descendant) edges. We first prove that deciding whether there is a tree homeomorphism is LOGSPACE-complete, improving on the current LOGCFL upper bound. As our main result we develop a practical algorithm for the tree homeomorphism decision problem that is both space- and time efficient. The algorithm is in LOGDCFL and space consumption is strongly bounded, while the running time is linear in the size of the data tree. This algorithm immediately generalizes to the problem of matching the tree pattern against all subtrees of the data tree, preserving the mentioned efficiency properties.

• Type: Conference
• Year: 2007
• Where: DBPL
• Authors: Michaela Götz, Christoph Koch, Wim Martens
• Keywords: Database, DBPL 2007, Tree Homeomorphism, Tree Pattern, Tree Pattern Matching