2010 | OriginalPaper | Chapter
Efficient Indexes for the Positional Pattern Matching Problem and Two Related Problems over Small Alphabets
Authors : Chih-Chiang Yu, Biing-Feng Wang, Chung-Chin Kuo
Published in: Algorithms and Computation
Publisher: Springer Berlin Heidelberg
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In this paper, we study the following three variants of the classical text indexing problem over small alphabets: the positional pattern matching problem, the position-restricted pattern matching problem, and the indexing version of the variable-length don’t care pattern matching problem. Let
n
be the length of the text,
p
be the length of a query pattern, and Σ be the alphabet. Assume that |Σ| =
O
(polylog(
n
)). For the first and third problems, we present
O
(
n
)-word indexes with
O
(
p
) query time. For the second problem, we show that each query can be answered in
O
(
n
log
ε
n
) space and
O
(
p
+
occ
) time, or in
O
(
n
) space and
O
(
p
+
occ
log
ε
n
) time, where
occ
is the number of outputs. When the alphabet size is
O
(polylog(
n
)), the indexes presented in this paper improve the results in [6, 10, 11, 22].