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 The Apache License is a permissive free software license written by the Apache Software Foundation (ASF). It allows users to use the software for any purpose, to distribute it, to modify it, and to distribute modified versions of the software ...

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 constructe ...

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

C++ C++ (, pronounced "C plus plus" and sometimes abbreviated as CPP or CXX) is a high-level, general-purpose programming language created by Danish computer scientist Bjarne Stroustrup. First released in 1985 as an extension of the C programmin ...

, with an interface to the library in

Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (prog ...

and a utility for looking up results from transducers ported to

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

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 Finite-state machines Free software programmed in C++ Free software programmed in Prolog Free software programmed in Python Cross-platform free software Free software for Linux Free software for Windows Free software for macOS Software using the GNU General Public License

Features

Uses

See also

Notes

External links

References