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The XML Framework Its Implications for Corpus Access and Use

Data Architectures and Software Support for Large Corpora Towards an American National Corpus. The XML Framework Its Implications for Corpus Access and Use. Nancy Ide Department of Computer Science Vassar College. XML.

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The XML Framework Its Implications for Corpus Access and Use

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  1. Data Architectures and Software Support for Large Corpora Towards an American National Corpus The XML FrameworkIts Implications for Corpus Access and Use Nancy Ide Department of Computer Science Vassar College

  2. XML • emerging standard for data representation and exchange on the World Wide Web • powerful tool for data representation and access • obvious standard for interchange of language resources • supports text, speech, video, audio • ...and linkage among them!

  3. XML provides more than SGML • better linkage mechanisms • XSLT for document access and transformation • XML schemas • provision for accessing all or part of multiple DTDs

  4. XML Links • "stand-off" annotation is the accepted norm for annotated resources • maintain all or most annotations in separate documents • each references appropriate locations in the original data • yields a finely linked hypertext format where the links specify a semantic role rather than navigational options

  5. Requirements of the stand-off architecture • address XML elements • address characters and chains of characters within those elements • address elements and characters both within the same document and in other XML documents

  6. XML Path Language (XPath) • concise notation for element localization in the document tree • /div/p[2]/s[3] - third sentence of second paragraph in each <div> • /descendant::p - all <p> elements • predicates for accessing characters within elements • substring(/p/s[2]/text(),10,12)

  7. XPointer • extends XPath syntax to allow : • addressing points and ranges as well as nodes • locating information by string matching • use of addressing expressions in URI-references as fragment identifiers

  8. XLink • uni- or multi-directional links • can specify how link is to be activated • by hand or automatically by the browser • can specify what to do with the target fragment • replace it or insert it into the source document

  9. Links to External Documents • None in SGML • HyTime/TEI invented "doc" attribute • CES used "doc" with inheritance to avoid repetition of the attribute • not supported by SGML processors • XML: XLink and xml:base attribute

  10. XSLT • a powerful tree-traversal language • translate any XML document into another document in any form • html • XML • plain text • etc. • most to offer for handling annotated resources

  11. XSLT Capabilities • selection of elements or portions of element content using the XPath syntax • rearrangement, transformation of extracted information (text content, element names, etc.) in the target document • addition of information to the target document

  12. A Simple Example • <?xml version="1.0"> • <chunk type="BODY" lang="en" • xml:base= • "http://www.cs.vassar.edu/~ME/Oen.xcesDoc#"> • <par xlink:href="xptr(substring(//p[1]"> • <s xlink:href="xptr(substring(//p/s[1]"> • <tok type="WORD" • xlink:href= • "xptr(substring(//p/s[1]/text(),1,2"> • <orth>It</orth> • <disamb> • <base>it</base> • <msd>Pp3ns</msd> • <ctag>PPER3</ctag></lex> • <lex> • <base>it</base> • <msd>Pp3ns</msd> • <ctag>PPER3</ctag></lex></tok>... xcesAna document

  13. XSLT creates HTML • <xsl:stylesheet version="1.0" • xmnls:xsl= • "http://www.w3.org/1999/XSL/Transform"> • <xsl:template match= “/”> • <html> • <body> • <xsl:apply-templates/> • </body> • </html> • </xsl:template> • <xsl:template match="//par"/> • <xsl:for-each select=”//tok”/> • <xsl:value-of select=”orth”/> • <xsl:text>|</xsl:text> • <xsl:value-of select=”disamb/base”/> • <xsl:text>|</xsl:text> • <xsl:value-of select=”disamb/ctag”/> • </xsl:for-each> • </xsl:template> • </xsl:stylesheet> XSLT document

  14. It|it|PPER3 • was|be|PAST3 • a|a|DINT • bright|bright|ADJE • cold|cold|ADJE • day|day|NN… Result

  15. Possibilities • create new documents containing selected annotations • transduce XML encoded documents to tool-internal formats • generate a new document with all phonemes that appear in a certain context (or all the unique contexts of a certain phoneme), etc.

  16. XML Schemas • constrain and document the meaning, usage and relationships of the constituent parts of XML documents • datatypes • elements and their content • attributes and their values • provide default values for attributes and elements

  17. Impact for language resources • provide means to define an abstract data model for a class of documents • e.g., data model for annotations and annotated objects • one of the most important tasks for corpus and tool creators • provide for much tighter validation of document form and content

  18. Capabilities • different attribute declarations and/or content models can apply to elements with the same name in different contexts • allows for more tightly constrained content models than possible with DTDs • e.g., <name> in header and <name> in text likely have different content constraints

  19. define equivalence classes for groups of elements and/or attributes • may be used in the same ways as defined for a particular named element • in CES used parameter entities to make a class of phrase-level objects (for example) • a "kludge"

  20. constrain attribute or element values (or combinations) to be unique, e.g., • only one entry in a computational lexicon can be defined with a given word form • only one paragraph can have an attribute indicating that it is the 23rd • only one disambiguated form is given for each token • only one correspondence for a given item in an alignment document Useful for error detection and prevention

  21. establish dependencies based on element or attribute values, for example: • prevent nouns from being assigned a tense • specify that tokens with type attribute value PUNCT include only <orth> elements containing specific characters • specify annotation labels elsewhere, constrain element content to these values only • e.g., constrain the values of the <msd> element in an XCES annotation document to the EAGLES morpho-syntactic specifications Another means for error control and validation

  22. Why is XML a good thing? • search, extraction, and transformation capabilities answer most current and foreseen needs for corpus-based language engineering • means to fully implement the stand-off data architecture • processing tools for XML recommendations are freely distributed • no need for costly and time-consuming tool development

  23. Conclusion • XML will allow for • representation of multi-lingual, multi-modal resources • implementation of the stand-off scheme • compatibility with the WWW, enabling • exploitation by LE researchers via the web • harmonization and combination of LRE resources with other WWW data • distributed model for data delivery

  24. P.S.... • A set of XML recommendations for encoding language resources exists: • XCES (XML version of the Corpus Encoding Standard--CES) • http://www.cs.vassar.edu/XCES

  25. Acknowledgements • Laurent Romary (LORIA/CNRS) • Patrice Bonhomme (LORIA/CNRS)

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