Constrained Approximate Subtree Matching by Finite Automata

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Constrained Approximate Subtree Matching by Finite Automata

Popis výsledku v původním jazyce

Processing tree data structures usually requires a pushdown automaton as a model of computation. Therefore, it is interesting that a finite automaton can be used to solve the constrained approximate subtree pattern matching problem. A systematic approach to the construction of such matcher by finite automaton, which reads input trees in prefix bar notation, is presented. Given a tree pattern and an input tree with m and n nodes, respectively, the nondeterministic finite automaton for the pattern is constructed and it is able to find all occurrences of the pattern to subtrees of the input tree with maximum given distance k. The distance between the pattern and subtrees of an input tree is measured by minimal number of restricted tree edit operations, called leaf nodes edit operations. The corresponding deterministic finite automaton finds all occurrences in time O(n) and has O(|A|^k m^(k+1)) states, where A is an alphabet containing all possible node labels. Note that the size is not exponential in the number of nodes of the tree pattern but only in the number of errors. In practice, the number of errors is expected to be a small constant that is much smaller than the size of the pattern. To achieve better space complexity, it is also shown how dynamic programming approach can be used to simulate the nondeterministic automaton. The space complexity of this approach is O(m), while the time complexity is O(mn).

Název v anglickém jazyce

Constrained Approximate Subtree Matching by Finite Automata

Popis výsledku anglicky

Processing tree data structures usually requires a pushdown automaton as a model of computation. Therefore, it is interesting that a finite automaton can be used to solve the constrained approximate subtree pattern matching problem. A systematic approach to the construction of such matcher by finite automaton, which reads input trees in prefix bar notation, is presented. Given a tree pattern and an input tree with m and n nodes, respectively, the nondeterministic finite automaton for the pattern is constructed and it is able to find all occurrences of the pattern to subtrees of the input tree with maximum given distance k. The distance between the pattern and subtrees of an input tree is measured by minimal number of restricted tree edit operations, called leaf nodes edit operations. The corresponding deterministic finite automaton finds all occurrences in time O(n) and has O(|A|^k m^(k+1)) states, where A is an alphabet containing all possible node labels. Note that the size is not exponential in the number of nodes of the tree pattern but only in the number of errors. In practice, the number of errors is expected to be a small constant that is much smaller than the size of the pattern. To achieve better space complexity, it is also shown how dynamic programming approach can be used to simulate the nondeterministic automaton. The space complexity of this approach is O(m), while the time complexity is O(mn).

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

10201 - Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8)

Projekt

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Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Proceedings of the Prague Stringology Conference 2018

ISBN

978-80-01-06484-9

ISSN

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e-ISSN

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Počet stran výsledku

12

Strana od-do

79-90

Název nakladatele

Czech Technical University in Prague

Místo vydání

Praha

Místo konání akce

Prague

Datum konání akce

27. 8. 2018

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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