2011 | OriginalPaper | Chapter
Faster Bit-Parallel Algorithms for Unordered Pseudo-tree Matching and Tree Homeomorphism
Authors : Yusaku Kaneta, Hiroki Arimura
Published in: Combinatorial Algorithms
Publisher: Springer Berlin Heidelberg
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In this paper, we consider the unordered pseudo-tree matching problem, which is a problem of, given two unordered labeled trees
P
and
T
, finding all occurrences of
P
in
T
via such many-one embeddings that preserve node labels and parent-child relationship. This problem is closely related to tree pattern matching problem for XPath queries with child axis only. If
m
>
w
, we present an efficient algorithm that solves the problem in
$O(nm\ log(w)/w)$
time using
O
(
hm
/
w
+
m
log(
w
)/
w
) space and
O
(
m
log(
w
)) preprocessing on a unit-cost arithmetic RAM model with addition, where
m
is the number of nodes in
P
,
n
is the number of nodes in
T
,
h
is the height of
T
, and
w
is the word length. We also discuss a modification of our algorithm for the unordered tree homeomorphism problem, which corresponds to a tree pattern matching problem for XPath queries with descendant axis only.