3.11.0 / September 16, 2016
|Written in||C++, Python, Java|
|Operating system||Cross-platform: Linux, Mac OS X, Windows|
|License||GPLv3, part Apache|
Helsinki Finite-State Technology (HFST) is a computer programming library and set of utilities for natural language processing with finite-state automata and finite-state transducers. It is free and open-source software, released under a mix of the GNU General Public License version 3 (GPLv3) and the Apache License.
The library functions as an interchanging interface to multiple backends, such as OpenFST, foma 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 Xerox'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 networks (RTNs).
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.
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.
- Official website
- https://kitwiki.csc.fi/twiki/bin/view/KitWiki/HfstHome - A documentation wiki
Lindén, Krister; Axelson, Erik; Drobac, Senka; Hardwick, Sam; Kuokkala, Juha; Niemi, Jyrki; Pirinen, Tommi; Silfverberg, Miikka (2013). "HFST - A System for Creating NLP Tools" (PDF). In Mahlow, Cersting; Piotrowski, Michael (eds.). Systems and Frameworks for Computational Morphology. Systems and Frameworks for Computational Morphology. Communications in Computer and Information Science. 380. Humboldt-Universität in Berlin: Springer. pp. 53–71.