Noriki Fujisato

dblp:225/4714 · DBLP profile ↗
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6ranked-venue papers
3as first author
3since 2021 · last 2022
—ORCID · none

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Theory of computation · 3 · 2 first-author · 2 since 2021Databases, data management, data science and information retrieval · 2 · 1 first-author · 1 since 2021Graphics, computer vision, multimedia, augmented reality and games · 1
YearPublicationVenuePosition
2022 Parameterized DAWGs: Efficient constructions and bidirectional pattern searches
abstract
Two strings $x$ and $y$ over $\Sigma \cup \Pi$ of equal length are said to \emph{parameterized match} (\emph{p-match}) if there is a renaming bijection $f:\Sigma \cup \Pi \rightarrow \Sigma \cup \Pi$ that is identity on $\Sigma$ and transforms $x$ to $y$ (or vice versa). The \emph{p-matching} problem is to look for substrings in a text that p-match a given pattern. In this paper, we propose \emph{parameterized suffix automata} (\emph{p-suffix automata}) and \emph{parameterized directed acyclic word graphs} (\emph{PDAWGs}) which are the p-matching versions of suffix automata and DAWGs. While suffix automata and DAWGs are equivalent for standard strings, we show that p-suffix automata can have $\Theta(n^2)$ nodes and edges but PDAWGs have only $O(n)$ nodes and edges, where $n$ is the length of an input string. We also give an $O(n |\Pi| \log (|\Pi| + |\Sigma|))$-time $O(n)$-space algorithm that builds the PDAWG in a left-to-right online manner. As a byproduct, it is shown that the \emph{parameterized suffix tree} for the reversed string can also be built in the same time and space, in a right-to-left online manner. This duality also leads us to two further efficient algorithms for p-matching: Given the parameterized suffix tree for the reversal of the input string $T$, one can build the PDAWG of $T$ in $O(n)$ time in an offline manner; One can perform \emph{bidirectional} p-matching in $O(m \log (|\Pi|+|\Sigma|) + \mathit{occ})$ time using $O(n)$ space, where $m$ denotes the pattern length and $\mathit{occ}$ is the number of pattern occurrences in the text $T$.
Katsuhito Nakashima, Noriki Fujisato, Diptarama, Yuto Nakashima 0001, Ryo Yoshinaka, Shunsuke Inenaga, Hideo Bannai, Ayumi Shinohara, Masayuki Takeda
Theor. Comput. Sci.2
2021 The Parameterized Suffix Tray
Noriki Fujisato, Yuto Nakashima 0001, Shunsuke Inenaga, Hideo Bannai, Masayuki Takeda
CIAC1
2021 Position Heaps for Cartesian-Tree Matching on Strings and Tries
Akio Nishimoto, Noriki Fujisato, Yuto Nakashima 0001, Shunsuke Inenaga
SPIRE2
2020 DAWGs for Parameterized Matching: Online Construction and Related Indexing Structures
abstract
Two strings x and y over Σ ∪ Π of equal length are said to parameterized match (p-match) if there is a renaming bijection f:Σ ∪ Π → Σ ∪ Π that is identity on Σ and transforms x to y (or vice versa). The p-matching problem is to look for substrings in a text that p-match a given pattern. In this paper, we propose parameterized suffix automata (p-suffix automata) and parameterized directed acyclic word graphs (PDAWGs) which are the p-matching versions of suffix automata and DAWGs. While suffix automata and DAWGs are equivalent for standard strings, we show that p-suffix automata can have Θ(n²) nodes and edges but PDAWGs have only O(n) nodes and edges, where n is the length of an input string. We also give O(n |Π| log (|Π| + |Σ|))-time O(n)-space algorithm that builds the PDAWG in a left-to-right online manner. As a byproduct, it is shown that the parameterized suffix tree for the reversed string can also be built in the same time and space, in a right-to-left online manner.
Katsuhito Nakashima, Noriki Fujisato, Diptarama, Yuto Nakashima 0001, Ryo Yoshinaka, Shunsuke Inenaga, Hideo Bannai, Ayumi Shinohara, Masayuki Takeda
CPM2
2019 The Parameterized Position Heap of a Trie
Noriki Fujisato, Yuto Nakashima 0001, Shunsuke Inenaga, Hideo Bannai, Masayuki Takeda
CIAC1
2019 Direct Linear Time Construction of Parameterized Suffix and LCP Arrays for Constant Alphabets
Noriki Fujisato, Yuto Nakashima 0001, Shunsuke Inenaga, Hideo Bannai, Masayuki Takeda
SPIRE1