NLP Resources
Contents
Tools : Machine Translation , POS Taggers , NP chunking , Sequence models , Parsers , Semantic Parsers/SRL , NER , Coreference , Language models , Concordances , Summarization , Other
Corpora : Large collections , Particular languages , Treebanks , Discourse , WSD , Literature , Acquisition
SGML/XML
Dictionaries
Lexical/morphological resources
Courses, Syllabi, and other Educational Resources
Mailing lists
Other stuff on the Web : General , IR , IE/Wrappers , People , Societies
Tools
Machine Translation systems
Instructions
Building a baseline statistical phrase MT system Wonderful pages about how to download a bunch of tools and some data and put them together to build a very competent baseline statistical MT system: NAACL 2006 WMt or 2009 WMT .
Freely downloadable
EGYPT system System from 1999 JHU workshop. Mainly of historical interest.
GIZA++ and mkcls Franz Och. C++. GPL.
Thot Phrase-based model building kit
Phramer An Open-Source Java Statistical Phrase-Based MT Decoder
Moses A new open-source phrase-based MT decoder with functionality beyond Pharaoh.
Syntax Augmented Machine Translation via Chart Parsing Andreas Zollmann and Ashish Venugopal
Free, but getting them requires hassle
Pharaoh decoder Philip Koehn, ISI.
MTTK Machine Translation Tool Kit. Deng and Byrne.
Part of Speech Taggers
Freely downloadable
Stanford POS tagger Loglinear tagger in Java (by Kristina Toutanova)
hunpos An HMM tagger with models available for English and Hungarian. A reimplementation of TnT (see below) in OCaml. pre-compiled models. Runs on Linux, Mac OS X, and Windows.
MBT: Memory-based Tagger Based on TiMBL
TreeTagger A decision tree based tagger from the University of Stuttgart (Helmut Scmid). It's language independent, but comes complete with parameter files for English, German, Italian, Dutch, French, Old French, Spanish, Bulgarian, and Russian. (Linux, Sparc-Solaris, Windows, and Mac OS X versions. Binary distribution only.) Page has links to sites where you can run it online.
SVMTool POS Tagger based on SVMs (uses SVMlight). LGPL.
ACOPOST (formerly ICOPOST) Open source C taggers originally written by by Ingo Schröder. Implements maximum entropy, HMM trigram, and transformation-based learning. C source available under GNU public license.
MXPOST : Adwait Ratnaparkhi's Maximum Entropy part of speech tagger Java POS tagger. A sentence boundary detector (MXTERMINATOR) is also included. Original version was only JDK1.1; later version worked with JDK1.3+. Class files, not source.
fnTBL A fast and flexible implementation of Transformation-Based Learning in C++. Includes a POS tagger, but also NP chunking and general chunking models.
mu-TBL An implementation of a Transformation-based Learner (a la Brill), usable for POS tagging and other things by Torbjörn Lager. Web demo also available. Prolog.
YamCha SVM-based NP-chunker, also usable for POS tagging, NER, etc. C/C++ open source. Won CoNLL 2000 shared task. (Less automatic than a specialized POS tagger for an end user.)
QTAG Part of speech tagger An HMM-based Java POS tagger from Birmingham U. (Oliver Mason). English and German parameter files. [Java class files, not source.]
The TOSCA/LOB tagger . Currently available for MS-DOS only. But the decision to make this famous system available is very interesting from an historical perspective, and for software sharing in academia more generally. LOB tag set.
The venerable Brill's Transformation-based learning Tagger A symbolic tagger, written in C. It's no longer available from a canonical location, but you might find a version from the Wikipedia page or you could try a reimplementation such as fnTBL .
Original Xerox Tagger A common lisp HMM tagger available by ftp .
Lingua-EN-Tagger Perl POS tagger by Maciej Ceglowski and Aaron Coburn. Version 0.11. (A bigram HMM tagger.)
Free, but require registration
TATOO The ISSCO tagger. HMM tagger. Need to register to download.
PoSTech Korean morphological analyzer and tagger Online registration.
TnT - A Statistical Part-of-Speech Tagger Trainable for various languages, comes with English and German pre-compiled models. Runs on Solaris and Linux.
Usable by email or on the web, but not distributed freely
Memory-based tagger From ILK group, Catholic University Brabant (Jakub Zavrel/Walter Daelemans). Does Dutch, English, Spanish, Swedish, Slovene. Other MBL demos are also available.
Birmingham tagger Accepts only plain ASCII email message contents. The tagset used is similar to the Brown/LOB/Penn set.
CLAWS tagger The UCREL CLAWS tagger is available for trial use on the web. (It's limited to 300 words though -- this site is more of an advertisement for licensing the real thing -- available as software for Suns or as a paid service.) You can also find info on CLAWS tagsets , though that page doesn't seem to link to the C7 tagset .
The AMALGAM tagger The AMALGAM Project also has various other useful resources, in particular a web guide to different tag sets in common use . The tagging is actually done by a (retrained) version of the Brill tagger (q.v.).
Xerox XRCE MLTT Part Of Speech Taggers Tags any of 14 languages (European and Arabic), online on the web.
Portuguese taggers on the web: Projecto Natura and a QTAG adaptation .
Not free
Lingsoft Lingsoft in Finland has (symbolic) analysis tools for many European languages. More information can be obtained by emailing
[email protected] . There is an online demo .
Conexor Conexor in Finland has demonstrations of EngCG-style taggers and parsers, for English, Swedish, and Spanish.
Xerox Xerox has morphological analyzers and taggers for many languages. There are demos of some of their tools on the web. More information can be obtained by contacting Daniella Russo .
Infogistics Infogistics , an Edinburgh spinoff has a tagging and NP/Verb group chunker available commercially, including an evaluation version.
No longer available
LT POS and LT TTT The Edinburgh Language Technology Group tagger and text tokenizer (and sentence splitter were binary-only Solaris tools which no longer seem to be available.
NP chunking
Downloadable
YamCha SVM-based NP-chunker, also usable for POS tagging, NER, etc. C/C++ open source. Won CoNLL 2000 shared task. (Less automatic than a specialized POS tagger for an end user.)
Mark Greenwood's Noun Phrase Chunker A Java reimplementation of Ramshaw and Marcus (1995).
fnTBL A fast and flexible implementation of Transformation-Based Learning in C++. Includes a POS tagger, but also NP chunking and general chunking models.
Generic sequence models
Downloadable
CRF++ Generic CRF-based model in C++. Open source. By the author of YamCha.
Carafe Generic CRF-based sequence models in O-CaML. Open source. By Ben Wellner.
FreeLing A large suite of language analyzers. Written in C++. Covers text preprocessing, morphology, NER, POS tagging, parsing.
Parsers
Information on available probabilistic parsers can be found on the FSNLP: probabilistic parsing links page.
Semantic Parsers
Downloadable
ASSERT PropBank semantic roles (and opinions, etc.) by Sameer Pradhan.
Shalmaneser FrameNet-based by Katrin Erk.
Tree Kernels in SVMlight by Alessandro Moschitti. A general package, but it has particularly been used for SRL.
Named Entity Recognition
Downloadable
Stanford Named Entity Recognizer A Java Conditional Random Field sequence model with trained models for Named Entity Recognition. Java. GPL. By Jenny Finkel.
LingPipe Tools include statistical named-entity recognition, a heuristic sentence boundary detector, and a heuristic within-document coreference resolution engine. Java. GPL. By Bob Carpenter, Breck Baldwin and co.
YamCha SVM-based NP-chunker, also usable for POS tagging, NER, etc. C/C++ open source. Won CoNLL 2000 shared task. (Less automatic than a specialized POS tagger for an end user.)
Coreference (Anaphora) Resolution
Downloadable
BART A Beautiful Anaphora Resolution Toolkit. Java. By Yannick Versley and many others. Java. Apache with GPL components.
Guitar Java. GPL.
Language modeling toolkits
Downloadable
IRSTLM Toolkit Compatible with SRILM, suitable for very large language models. LGPL. By Marcello Federico, Nicola Bertoldi et al.
CMU-Cambridge Statistical Language Modeling toolkit
Downloadable, but requires registration
The SRI Language Modeling toolkit by Andreas Stolcke is another good system for building language models, freely available for research purposes.
Not yet classified
Lextools A package of tools for creating weighted finite-state transducers (WFST) from high-level linguistic descriptions. Lextools binaries are available free for non-commercial use at: http://www.research.att.com/sw/tools/lextools/ . Supported platforms are: linux (i686), sgi (mips2) and sun4. Lextools is built on top of, and requires, the AT&T WFST toolkit (version 3.6), available free for non-commercial use from: http://www.research.att.com/sw/tools/fsm/
Friendly concordancing and text analysis tools
Wordsmith Tools (Mike Scott) The thing to get if you are working in the Windows world.
Text summarization tools
A prototype Java Summarisation applet (System Quirk)
MEAD A public domain portable multi-document summarization system. (Dragomir Radev and others.)
Other
Downloadable
Tilburg University's TiMBL Tilburg's Memory Based Learner by Walter Daelemans et al. A general near-neighbour-based machine learning package, but optimized for statistical NLP applications.
Time Expression taggers TIMEX2 standard taggers (site at Mitre).
NLTK An open source Python package for NLP application development with tools such as tokenization, POS TAGGING and parsers by Ed Loper and Steven Bird.
Ted Pedersen's code Ngram Statistics Package: Perl code that implements: Fisher's exact test, the likelihood ratio, Pearson's chi squared test, the Dice Coefficient, and Mutual Information; Duluth Senseval-2 word sense disambiguation systems; Senseval-1 data in Senseval-2 format; various other WSD datasets in Senseval formats, and semantic distances derived via WordNet.
ISIP tools The main aim is a publically available speech recognition system (alpha release available), but along the way there are also toolkits for discrete HMMs and statistical decision trees, and for various aspects of signal processing.
Mem . A Perl implementation of Generalized and Improved Iterative Scaling by Hugo WL ter Doest.
Automorphology A system (for Windows) for automatically learning the morphological forms of words in a corpus by John Goldsmith.
Wordnet Wordnet is available by ftp , compiled for a variety of machine types. For money, one can also get EuroWordNet for various European languages, an Italian/English/Spanish MultiWordNet and there's now a site for Global Wordnet . (See also Mappings between WordNet versions and Perl WordNet-Similarity module by Ted Pedersen, and WordNet Domains (coarse-grained sense topic classifications).)
Penn XTAG project A wide-coverage tree-adjoining grammar written in a mixture of C and Common Lisp. Also includes a large coverage morphological analyzer. Now includes more tools such as TCL/Tk tree viewer.
Dan Melamed's Assorted Tools A collection of various tools including a simulated annealling program, a post-processor for English stemming for the Penn XTAG morphology system, Good-Turing smoothing software, general text processing tools, text statistics tools and bitext geometry tools (mainly written in Perl 5).
MULTEXT Constructing corpora and tools for processing multilingual corpora. Contact: Jean Veronis
[email protected] . Some stuff including a multilingual text editor is downloadable. MULTEXT EASThas parallel versions of Orwell's 1984 available free (upon registration) for a number of Central European languages.
Naive Bayes algorithm Software from the Rainbow/Libbow software package that implements several algorithms for text categorization, including naive Bayes, TF.IDF, and probabilistic algorithms. Accompanies Tom Mitchell's ML text.
HDDI Text Data Mining API from Lehigh University.
Emdros: a text database engine for linguistic analysis and research
Chasen Japanese morphological analyzer. Descendent of JUMAN.
Free, but require registration
Stuttgart's IMS Corpus Workbench (CWB) A workbench for full-text retrieval from large corpora (with a query language and corpus indexing). Includes the Corpus Query Processor (CQP) and xkwic. Available free for research groups (currently only as Solaris 1/2 or Linux binaries), on signing a license agreement.
Gate University of Sheffield's General Architecture for Text Engineering. Primarily an Information Extraction system.
MITRE's Alembic Workbench A workbench for the development of tagged corpora. Includes a tagger based on Brill's TBL approach.
SNoW SNoW is a learning program that can be used as a general purpose multi-class classifier and is specifically tailored for learning in the presence of a very large number of features. The learning architecture is a sparse network of linear units over a pre-defined or incrementally acquired feature space (Dan Roth).
Unsure
INTEX a finite-state transducer analysis system for English, French, and Italian that runs under NextStep. Contact: Max Silberztein
[email protected]
The PennTools page collects information on a variety of NLP systems, many of which are available externally.
Corpora
Large collections aimed at the NLP community
LDC (Linguistic Data Consortium) and its catalogue by year . Email:
[email protected] . Provides the largest range of corpora on CD-ROM. Cost ranges from cheap (e.g., ACL-DCI disk) to pricey. CDs can be purchased individually; institutions can become members and receive discounts on CDs. There's an LDC Online service for searches over the web (mainly intended for members, but there are samplers available).
European Language Resources Association and its catalogue . Distribution agency is ELDA . Rapidly growing collection of materials in European languages.
ICAME (International Computer Archive of Modern English) Sells various corpora (including Brown and London-Lund). Information on corpora on the web , by sending the message
help to
[email protected] , by ftp to
nora.hd.uib.no . Also, manualsfor these corpora.
Reuters @ NIST Reuters corpora are now distributed by NIST.
TRACTOR TELRI Research Archive of Computational Tools and Resource. Corpora, many multilingual, in European community languages. Small fee for joining in order to be able to get corpora (unless you have contributed corpora).
CLR (Consortium for Lexical Research) Email:
[email protected] . Focuses more on language processing tools and lexicons, but does have some corpora. As of Feb 1996, you can get most of their stuff by anonymous ftp to
clr.nmsu.edu . Their catalog is available as a postscript file.
OTA (Oxford Text Archive) Provides mainly literary texts. Has a bright new web site. Email:
[email protected] . Most materials are available on the web or by anonymous ftp to
ota.ox.ac.uk . Some require negotiations with the providers.
Leipzig Corpora Collection Sentence collections in MySQL database for 17 mainly European languages.
BNC (British National Corpus) A 100 million word corpus of British English. You can search it online from their simple web interface or via View , a much better interface by Mark Davies, and there is an index to genres by David Lee. And now, an XML edition .
European Corpus Initiative Multilingual Corpus I (ECI/MCI) A 98 million word corpus, covering most of the major European languages, as well as Turkish, Japanese, Russian, Chinese, and Malay. Cheap. Need to sign a license agreement available at either the WWW site. Also available from the LDC.
Survey of English Usage At the Department of English Language and Literature at University College London. Includes the British part of ICE , the International Corpus of English project. Now available tagged, and parsed for function. 83,419 sentences. Includes ICECUP, dedicated retrieval software. Also, Diachronic Corpus of Present-Day Spoken English (800,000 words, tagged and parsed, half from ICE-GB and half from London-Lund).
International Corpus of English (ICE) Million word collections of English from various world Englishes: ICE-NZ, ICE-HK, ICE-East Africa, etc. Several of them are downloadable from this site.
Corpora held by Lancaster University This link provides its own annotations.
The European Language Activity Network Promises a uniform query language for accessing corpora in all EU languages -- but isn't quite there yet.
Talkbank . Rich video and transcripts.
Particular languages
English
English language corpora available from the sites above are not repeated here.
Corpora by Geoffrey Sampson's team The SUSANNE corpus and the CHRISTINE corpus (SUSANNE markup of a speech corpus).
Michigan Corpus of Academic Spoken English (MICASE) . 1.7 million words from 1997-2001.
Penn-Helsinki Parsed Corpus of Middle English A syntactically annotated corpus of the Middle English prose samples in the Helsinki Corpus of Historical English, with additions. 1.3 million words. $200.
Corpus of Professional, Spoken American-English (CPSA) 2 million words from faculty and committee meetings and White House press conferences (50K work sample free on internet).
Lancaster Parsed Corpus
Dialogue Diversity Corpus (Bill Mann)
American National Corpus
Chinese
English language corpora available from the sites above are not repeated here.
The Lancaster Corpus of Mandarin Chinese (LCMC) By Tony McEnery and Richard Xiao. Distinguished by being a balanced corpus, and freely available.
Multilingual
JRC-Acquis A parallel corpus of EU documents across all member states. 8 million words or more in each of 20 languages.
EMILLE/CIIL Monolingual written corpus data for 14 South Asian languages (Assamese, Bengali, Gujarati, Hindi, Kannada, Kashmiri, Malayalam, Marathi, Oriya, Punjabi, Sinhala, Tamil, Telegu and Urdu). Orthographically transcribed spoken data and parallel corpus data for five South Asian languages (Bengali, Gujarati, Hindi, Punjabi and Urdu). In addition, the parallel corpus contains the English originals from which the translations stored in the corpus were derived. All data in the corpus is CES and Unicode compliant. The EMILLE corpus totals some 94 million words. Downloadable.
OPUS An open source parallel corpus, aligned, in many languages, based on free Linux etc. manuals.
World Health Organization Computer Assisted Translation page . Also includes a good selection of links on Computer Assisted Translation. (See also the copyright page .)
Searchable Canadian Hansard French-English parallel texts (1986-1993) From the Laboratoire de Recherche Appliquée en Linguistique Informatique, Universite de Montréal
European Union web server Parallel text in all EU languages. (In particular try European legislation .)
TELRI CD-ROMs Parallel and other text in central and eastern european languages.
Bosnian
The Oslo Corpus of Bosnian Texts .
Czech
Parallel Czech-English Literature translations in Czech and English
Czech National Corpus project: SYN2000 100 million words of contemporary Czech.
French
Association des Bibliophiles Universels Various French literary works.
American and French Research on the Treasury of the French Language (ARTFL) 150 million word corpus of various genres of French. You have to be a member to use it (but membership is fairly cheap).
German
COSMAS Corpus Large (over a billion words!) online-searchable German and Austrian corpora. This is the publically available part of the 1.85 billion word Mannheimer Corpus Collection
NEGRA Corpus Saarland University Syntactically Annotated Corpus of German Newspaper Texts. Available free of charge to academics. 20,000 sentences, tagged, and with syntactic structures. Free for academic use.
Russian
Russian National Corpus 150 million words, 5 million words POS-tagged, some in dependency treebank.
Library of Russian Internet Libraries Various literary works.
Slovene
Slovene-English parallel corpus 1 M words, free to download + on-line concordances.
Coming soon: Slovene reference corpus of 100 M words
Spanish and Portuguese
TychoBrahe Parsed Corpus of Historical Portuguese Over a million words of Portuguese from different historical periods, some of it morphologically analyzed/tagged. Free.
Information about Mark Davies' collection of (mainly historical Spanish and Portuguese . It's not clear what their availability is.
The CUMBRE corpus. Contact Professor Aquilino Sánchez
The CRATER Spanish corpus Morphosyntactically tagged telecommunication manuals) is available by ftp .
Corpus resources for Portuguese In total about 70 million words, available free, from various sources (newswire, etc.)
Folha de S. Paulo newspaper 4 annual CDROMs with full text.
COMPARA Portuguese-English parallel corpus. (In general, various resources at Linguateca site.
See also under ELRA, above.
Swedish
Spraakdata , Department of Swedish, Göteborgs University. Has various searcable part of speech tagged Swedish corpora (Parole, Bank of Swedish, etc.), and some material in Zimbabwean languages.
Treebanks
Name Language Size Availability Comments| Penn Treebank | US English | 2 million + words | Available (distributed by LDC) | 1 million WSJ, 1 million speech, surface syntax (1970s TG) |
| BLLIP WSJ corpus | US English | 30 million words | Available (distributed by LDC) | WSJ newswire. Automatically parsed, not hand checked. Same structure as Penn Treebank, except for some additional coreference marking |
| ICE-GB | UK English | 1 million words (83,394 sentences) | Available; c. 500 pounds | British part of ICE, the International Corpus of English project. Tagged and parsed for function. Half spoken material. |
| NEGRA Corpus | German | 20,000 sentences | Available free of charge to academics on completion of license agreement. | Saarland University Syntactically Annotated Corpus of German Newspaper Texts. Tagged, and with syntactic structures. |
| TIGER corpus | German | 700,000 words | Available free of charge for research purposes on completion of license agreement. | German newspaper text (Frankfurter Rundschau). Semi-automatically parsed. They also have a good treebank search tool, TIGERSearch . |
| Alpino Dependency Treebank | Dutch | 150,000 words | Freely downloadable | Assorted subcorpora. By far the largest is the full cdbl (newspaper) part of the Eindhoven corpus. |
| The Prague Dependency Treebank 1.0 | Czech | 500,000 words | Free on completion of license agreement (available through LDC). | Analyzed at the levels of parts of speech, syntactic functions (and, in the future, semantic roles) level in a dependency framework. Text from newspapers and weekly magazines. |
| TUT: Turin University Treebank | Italian | 2,400 sentences | Free download. | Morhpological analysis and dependency analysis. Penn Treebank translation. Civil law and newspaper texts. |
| Bulgarian Treebank | Bulgarian | n/a | POS-tagged texts and dependencies analyses are available (some are free on the web, others via a license agreement) | An under construction Bulgarian HPSG treebank. |
| Penn Chinese Treebank | Chinese | 100,000 words | Available (LDC ) | Based on Xinhua news articles. 1980s-style GB syntax. |
| Danish Dependency Treebank 1.0 | Danish | 100,000 words | Available free under the GPL. | Built on a portion of the Parole corpus. |
| Floresta Sintá(c)tica | Portuguese | 168,000 words hand-corrected; 1,000,000 words automatically parsed | Hand corrected part is free web download; automatically parsed part available through email contact | Text from CETEMPúblico corpus . Phrase structure and dependency representations. Available in several formats, including Penn Treebank format. |
| Talbanken05 | Swedish | 300,000 words | Free download | Resurrects and modernizes an early treebank from the 1970s. |
Verbmobil Tübingen : under construction treebanked corpus of German, English, and Japanese sentences from Verbmobil (appointment scheduling) data
Syntactic Spanish Database (SDB) University of Santago de Compostela. 160,000 clauses / 1.5 million words.
CKIP Chinese Treebank (Taiwan) . Based on Academia Sinica corpus. (There's also a 100 sentence Chinese treebank at U. Maryland.)
LDC Korean Treebank .
Dublin-Essex Treebank project Deriving Linguistic Resources from Treebanks.
Treebanks
CSTBank : Cross-document Structure Theory: marking sentence functional relationships across related documents.
Resources for Word Sense Disambiguation
The Senseval web site Has a comprehensive selection of resources for WSD, including a good list of WSD data resources , but not yet the new SEMCOR .
Ted Pedersen's code Includes various WSD systems.
SenseClusters Open source package for unsupervised discovery of word senses by clustering together instances of a word (or words) that are used in similar contexts in raw text, supporting a wide range of clustering techniques based on both context vectors and similarity matrices, and including links to SVDPACKC and CLUTO. Ted Pedersen and Amruta Purandare.
Evocation WordNet synset similarity judgments Judgments on how similar the meanings of synsets are and how common they are in the BNC from Jordan Boyd-Graber.
Literature
There are now quite large collections of online literature, available in various languages (though the majority are in English, of course). Below are pointers to some of the main collections:
Entirely or mainly English
Alex: A Catalogue of Electronic Texts on the Internet Seems to have one of the largest collection. Searching and browsing facilities through gopher menus. Many languages.
Wiretap Electronic Text Archive Extensive and good quality. Still in the gopher age, though.
The On-line Books Page The index here only covers books in English, but there are lots of links to other collections of material in all languages.
Project Gutenberg The oldest and largest project to get out of copyright literature online, freely available. (Or see the mirror, Sailor's Project Gutenberg site .)
The Electronic Text Center of the University of Virginia Large collection of SGML text, mainly in English, but also in other major languages.
Center for Electronic Texts in the Humanities Princeton/Rutgers collaboration. They didn't have it together with their web site when I stopped by, but they may soon.
Oxford Electronic Text Library Editions Available from Oxford University Press, 200 Madison Ave, NY, NY 10016 212-679-7300. The Complete Works of Jane Austen is $95.00, and is reviewed in
Computers and the Humanities , 28:4-5 (Aug/Oct, 1994), 317-321.
Coreference annotated texts From University of Woverhampton (R. Mitkov, C. Barbu et al.).
Acquisition data
CHILDES database . Database of child language transcriptions in English and many other languages. Texts are also available by ftp . Certain usage requirements. Manuals and programs for accessing the data (the CLAN concordancer) are also available online. Now in Unicode XML.
SGML/XML
Robin Cover's SGML/XML Web Page This is a wonderful compendium of information on SGML and XML, including information on the Text Encoding Initiative (TEI) . This document is also a guide to many text collections (ones usi