The Text Encoding Initiative and the GENIA Corpus

1. The Text Encoding Initiative
2. Encoding the GENIA corpus in TEI
3. Further annotation of GENIA with XML tools

• The Text Encoding Initiative was established in 1987 under the joint sponsorship of the:
  • ACH: Association for Computers and the Humanities
  • ACL: Association for Computational Linguistics
  • ALLC: Association for Literary and Linguistic Computing.
• Impetus for the project came from the humanities computing community, which sought a common encoding scheme for complex textual structures in order to:
  • reduce the diversity of existing encoding practices,
  • simplify processing by machine,
  • encourage sharing of electronic texts.
  It soon became apparent that a sufficiently flexible scheme could provide solutions for text encoding problems generally.

• TEI became the only systematized attempt to develop a fully general text encoding model and set of encoding conventions based upon it, suitable for processing and analysis of:
  • any type of text,
  • in any language,
  • and intended to serve the increasing range of existing (and potential) applications and use.
• SGML, the Standard Generalized Markup Language, an ISO standard, was chosen as the underlying standard for the TEI Guidelines.
• The first draft of the TEI Guidelines for Electronic Text Encoding and Interchange, TEI P1 were published in 1990; the second draft, TEI P2 followed in 1993.

• TEI P3, the first non-draft version, were published in 1994 in two substantial green volumes (1200pp); soon P3 also became available on the Web.
• In the years since, TEI P3 has become the de facto standard for scholarly work with digital text.
• In 1999, a revised edition of TEI P3 was produced, correcting several typographic and other errors.
• But in 1998, Version 1.0 of the XML specification was published by the W3C, and soon becomes an unprecedented success.

• XML is a definition of device-independent, system-independent methods of storing and processing texts in electronic form
• XML is a metalanguage - a language for describing other languages - which lets you design your own customized markup languages for different types of documents
• XML is a project of the World Wide Web Consortium (W3C), and the development of the specification is being supervised by their XML Working Group; hence, it is an open and non-proprietary specification
• XML is a subset of SGML, the international standard metalanguage for text markup systems (ISO 8879)

• In December 2000 the TEI Consortium was set up to maintain and develop the TEI standard.
• The Consortium is a non-profit corporation, has executive offices in Bergen, Norway, and hosts at at the University of Bergen, Brown University, Oxford University, and the University of Virginia.
• The Consortium is managed by a Board of Directors, and its technical work is overseen by an elected Council. Lou Burnard is European editor and Syd Bauman is North American Editor.
• Institutions and individuals can become Consortium members or subscribers, which gives them certain benefits inside the consortium.
• The consortium has now over 50 members, from small university research projects to major academic libraries and institutions.

• TEI Guidelines define a language for describing how texts are constructed and propose names for their components.
• There are many such standard vocabularies in the industrial world (e.g. banking, aircraft maintenance, chemical modelling); TEI's achievement has been to try to do the same thing for textual and linguistic data.
• TEI Guidelines consist of:
  • the formal specification, consisting of a set of SGML/XML Document Type Definition (DTD) fragments; these DTDs specify the element grammar of valid TEI documents;
  • the accompanying documentation, explaining the background and overall structure of TEI document modelling and describing the meaning of the formaly defined elements.
• The Guidelines follow Knuth's literate programming practice, where the source (itself written in TEI) contains the formal specification as well as the documentation.

Quality

Using a wide-coverage, well-designed (modular and extesible), widely accepted and maintained architecture.

Documentation

TEI is documented in the Guidelines as well as papers and support documentation of various projects, e.g. “best practice guides”.

Training

Tutorials on TEI are given at various conferences and are actively promoted by by the TEI Consortium.

Support

Specific problems might have been encountered before, and people exist that know how to solve them, e.g. on the tei-l public discussion list.

Software

Various software to process TEI already exists, and more is likely to become available.

Political correctness: Using TEI means contributing to open standards and recommendations.

Tag abuse

TEI might not have elements / attributes with the exact meaning we require; this results in a tendency to misuse tags for purposes they were not meant for.

Tag bloat

being a general purpose recommendation, it can never be optimal for a specific application, i.e. a custom developed DTD will be leaner; have less (redundant) tags.

TEI for humanities

TEI is maybe the least developed for “high level” NLP applications: is problematic for encoding ontologies and lexical databases; not many applications of feature structures.

• The GENIA project is being undertaken at Tsujii Laboratory, University of Tokyo and is partially supported by JSPS Research for the Future program.
• GENIA seeks to automatically extract useful information from texts written by scientists to help overcome the problems caused by information overload.
• The prototype domain of application is bio-medicine, in particular extracting event information about protein interactions.
• The project is building a corpus, which, supported by other types of resources, is to be used as a testbed for the application domain.

• The GENIA corpus consists of annotated abstracts taken from National Library of Medicine's MEDLINE database.
• The corpus includes local (abstract specific) lexica and ontologies.
• The corpus is encoded in XML, using the GPML (GENIA Project Markup Language) DTD.
• Version 1.1 was released in September 2001, and consists of 670 abstracts (cca 130,000 words), and is publicly available.
• Version 1.1 is sentence segmented, and manually annotated for terms and, in some cases clauses.
• Version 2.0 is to be larger, and is to contain further linguistic and domain specific annotation, e.g. tokenisaton, part-of-speech tags, (shallow) parsing, lexical information, etc.

• The GENIA markup language is GMPL, an XML DTD specifically defined for the GENIA corpus.
• TEI is well-designed and widely accepted XML architecture, which has been often used for annotating language corpora
• By re-coding the GPML corpus to TEI:
  • GENIA can gain new insights into possible encoding practices (e.g. header information)
  • the GENIA corpus might become better suited for interchange
  • the TEI encoding can serve as a blueprint for a general standard for encoding bio-medical data, a rapidly expanding field.
• With an automatic transform to TEI there is also no need to abandon the GPML format, which, as it has been crafted specially for GENIA, provides a tighter encoding than can be possible with the more general TEI.

• The conversion process takes advantage of the fact that both the input (GPML) and output (TEI) are encoded in XML: it is an XSLT stylesheet.
• The W3C recommendation XSL Transformation Language, XSLT enables the declarative specification of transformation between XML documents.
• There exist a number of free XSLT processors; the best current implementations of the specification seem to be Mike Kay's Saxon and Daniel Veillard's libxslt.

<!DOCTYPE teiCorpus.2
    PUBLIC "-//TEI P4//DTD Main Document Type//EN" 
           "http://www.tei-c.org/P4X/DTD/tei2.dtd" [ 
  <!ENTITY % TEI.XML          "INCLUDE" >
  <!ENTITY % TEI.general      "INCLUDE">
  <!ENTITY % TEI.prose        "INCLUDE">
  <!ENTITY % TEI.dictionaries "INCLUDE">
  <!ENTITY % TEI.terminology  "INCLUDE">
  <!ENTITY % TEI.linking      "INCLUDE">
  <!ENTITY % TEI.analysis     "INCLUDE">
  <!ENTITY % TEI.fs           "INCLUDE">
  <!ENTITY % TEI.corpus       "INCLUDE">
  <!ENTITY % TEI.extensions.ent SYSTEM 'geniaex.ent'>
  <!ENTITY % TEI.extensions.dtd SYSTEM 'geniaex.dtd'>
]>

<!DOCTYPE teiCorpus.2 SYSTEM "genia-tei.dtd">

<TEIcorpus.2>
  <teiHeader type="corpus">*Corpus_header*</teiHeader>
  <TEI.2 id="*MEDLINE_ID*">
    <teiHeader type="text">*Article_header*</teiHeader>
    <text>
      <body>
        <div type="abstract">
           <head>*Title_of_article*</head>
           <p>*Abstract_of_article*</p>
        </div>
        <div type="ontology">*Local_ontology*</div>
        <div type="lexicon">*Local_lexicon*</div>
      </body>
    </text>
  </TEI.2>
  *More_articles*
</TEIcorpus.2>

<div type="abstract">
  <head>Retinoic acid downmodulates erythroid differentiation and 
    <term ana="SEM-94.000">GATA1 expression</term> in 
    <term ana="SEM-94.001">purified adult-progenitor culture</term>.
  </head>
  <p>
    <s>
      In 
      <cl ana="SEM-94.011 SEM-94.012" 
          function="(OR SEM-94.011 SEM-94.012)">
        <term ana="SEM-94.013">clonogenetic fetal calf serum</term>
        <term ana="SEM-94.014">-supplemented (FCS+)</term> 
        or 
        <term ana="SEM-94.015">-nonsupplemented (FCS-)</term> 
        <term ana="SEM-94.016">culture</term>
      </cl> 
      treated with saturating levels of 
      <term ana="SEM-94.018">interleukin-3</term> 
      (<term ana="SEM-94.019">IL-3</term>) 
      <term ana="SEM-94.020">granulocyte- macrophage 
         colony-stimulating factor</term> ...
    </s> 
    ...

• Edinburgh's Language Technology Group (LTG) has produced an XML toolchest for natural language processing.
• The tools are modular with stream input/output, and can be combined together in a pipeline.
• The release available runs on Sun/Solaris and is provided free of charge under a research license.
• The main component of the toolchest is a general purpose cascaded transducer which processes an input stream deterministically and rewrites it according to a set of rules provided in a grammar file.
• With the toolchest come various grammars, most importantly one to tokenise text. The grammars are accompanied by documentation which allows users to alter grammars to suit your own needs or develop new rule sets for particular purposes.
• The system also contains two statistical components: a part-of-speech tagger and a sentence boundary disambiguator.

• TEI, the framework to annotate linguistic data
• Applying TEI to the GENIA corpus
• Further processing of the GENIA corpus using XML technology