Helsinki Finite-State Technology (HFST) is a computer programming

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and set of utilities for natural language processing with finite-state automata and

finite-state transducer A finite-state transducer (FST) is a finite-state machine with two memory ''tapes'', following the terminology for Turing machines: an input tape and an output tape. This contrasts with an ordinary finite-state automaton, which has a single tape. ...

s. It is

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, released under a mix of the

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version 3 (GPLv3) and the Apache License.

Features

The library functions as an interchanging interface to multiple backends, such as OpenFST,

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and SFST. The utilities comprise various compilers, such as hfst-twolc (a compiler for morphological two-level rules), hfst-lexc (a compiler for lexicon definitions) and hfst-regexp2fst (a regular expression compiler). Functions from

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's proprietary scripting language xfst is duplicated in hfst-xfst, and the pattern matching utility pmatch in hfst-pmatch, which goes beyond the finite-state formalism in having

recursive transition network A recursive transition network ("RTN") is a graph theoretical schematic used to represent the rules of a context-free grammar. RTNs have application to programming languages, natural language and lexical analysis. Any sentence that is construct ...

s (RTNs). The library and utilities are written in

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, with an interface to the library in

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and a utility for looking up results from transducers ported to

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and Python. Transducers in HFST may incorporate weights depending on the backend. For performing FST operations, this is currently only possible via the OpenFST backend. HFST provides two ''native'' backends, one designed for fast lookup (''hfst-optimized-lookup''), the other for format interchange. Both of them can be weighted.

Uses

HFST has been used for writing various linguistic tools, such as spell-checkers, hyphenators, and morphologies. Morphological dictionaries written in other formalisms have also been converted to HFST's formats.

Notes

External links

* * https://github.com/hfst/hfst/wiki - A documentation wiki

References

{{cite conference , url= https://researchportal.helsinki.fi/en/publications/hfsta-system-for-creating-nlp-tools , title= HFST - A System for Creating NLP Tools , first1= Krister , last1= Lindén , first2= Erik , last2= Axelson , first3= Senka , last3= Drobac , first4= Sam , last4= Hardwick , first5= Juha , last5= Kuokkala , first6= Jyrki , last6= Niemi , first7= Tommi , last7= Pirinen , first8= Miikka , last8= Silfverberg , date= 2013 , conference= Systems and Frameworks for Computational Morphology , conference-url= http://sfcm.eu/sfcm2013/ , editor1-first= Cerstin , editor1-last= Mahlow , editor2-first= Michael , editor2-last= Piotrowski , series= Communications in Computer and Information Science , volume= 380 , book-title= Systems and Frameworks for Computational Morphology , publisher= Springer , location= Humboldt-Universität in Berlin , pages= 53–71 Free software Finite automata

Features

Uses

See also

Notes

External links

References