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This study presents an abstract data model for linguistic annotations and its implementation using XML, RDF, and related standards. It outlines the work of the ISO committee TC 37/SC 4 Language Resource Management and solicits the participation of the research community.
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Standards for Language Resources Nancy IDE Department of Computer Science Vassar College Laurent ROMARY Equipe Langue et Dialogue LORIA/INRIA IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Goals • present an abstract data model for linguistic annotations and its implementation using XML, RDF and related standards • outline work of newly formed ISO committee: TC 37/SC 4 Language Resource Management • Using the work described as its starting point • Solicit the participation of members of the research community IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Goals of ISO TC 37/SC 4 • prepare international standards/guidelines for effective language resource (LR) management in mono- and multi-lingual applications • develop principles and methods for creating, coding, processing and managing LR • written corpora, lexical corpora, speech corpora, dictionary compiling and classification schemes • Focus : • data modeling • data exchange, evaluation IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Standardization Process • Two-phases: • Develop basic architecture to support wide-range of applications • Use as basis for building more precise standards for LR management • Liaison with ISLE • Incorporate existing standards where possible • Broaden by including additional languages (e.g. Asian) IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Standardization is Tricky • Skepticism within the community • Arguments against LR standardization: • diversity of theoretical approaches makes standardization impractical or impossible • vast amounts of existing data and processing software will be rendered obsolete by the acceptance of new standards IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
SC4 Approach • Efforts geared toward defining abstract models and general frameworks for creation and representation of language resources • In principle, abstract enough to accommodate diverse theoretical approaches • Situate development squarely in the framework of XML and related standards • Ensure compatibility with established and widely accepted web-based technologies • Ensure feasibility of transduction from legacy formats into newly defined formats IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Call for Participation • Success of the committee depends on community’s awareness of its activity, in order to ensure widespread adoption • Involve from the outset broad range of potential users of the standards IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
The General Framework • Model for linguistic annotation that can • be instantiated in a standard representational format • serve as a pivot format into and out of which proprietary formats may be transduced to enable • comparison • merging • manipulation via common tools IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Overall Plan Annotation Format Tower of Babel Format A Abstract Format Format B Format C Operation via common tools, merging, etc IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
XSLT Script DATA CATEGORY REGISTRY Universal Resources STRUCTURAL SKELETON Project SpecificResources Data Category Specification Virtual AML Dialect Specification Abstract XML encoding Concrete AML Concrete XML encoding Overall Architecture Non-XML Encoding IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
N.B. • We do not expect XML to necessarily serve as the internal format used by tools etc. • We do not care about creating yet another “standard” format • We do not care (for this work) about designing specific annotation formats IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Data Model • Identify a consistent underlying data model for data and its annotations • Formalized description of data objects • Composition • Attributes • Class membership • Applicable procedures, etc • Formalized description of relations among data objects • Independent of instantiation in any particular form IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
(Most) Abstract Model • An annotation is a set of data or information associated with some other data • More precise: an annotation is a one- or two-way link between • an annotation object, and • a point or span (or a list/set of points or spans) within a “base” data set • Links may or may not have a semantics • Points and spans may be objects, or sets/lists of objects IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
ANNOTATION OBJECT ANNOTATION OBJECT ANNOTATION OBJECT [ [ [ ANNOTATION OBJECT PRIMARY DATA IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Observations • Granularity of the data representation and encoding is critical • Must be possible to represent objects and relations in some form that prevents information loss IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Representing Annotation Objects • Annotation objects may be relatively complex • Abstract representation • graph of elementary structural nodes to which one or more information units are attached • distinction between structure and information units is critical to the design of a truly general model • Annotations may be structured in several ways • Most common: hierarchical • phrase structure analyses of syntax • lexical and terminological information • etc. IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Relations Among Annotations • Parallelism • two or more annotations refer to the same data object • Alternatives • two or more annotations comprise a set of mutually exclusive alternatives • Aggregation • two or more annotations comprise a list or set that should be taken as a unit IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Information Units • Also called data categories • provide the semantics of the annotation • most theory and application-specific part of an annotation scheme • No attempt to define data categories • Proposal : development of a Data Category Registry • Define data categories with RDF schemas • Formalize properties and relations • Templates that describe how objects are instantiated • Inheritance of appropriate properties IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Data Category Registry • Several functions • provide a precise semantics for annotation categories • can be used “off the shelf” or modified • provide a set of reference categories onto which scheme-specific names can be mapped • provide a point of departure for definition of variant or more precise categories • Overall goal • Ensure that semantics of data categories are well-defined and understood IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Generic Mapping Tool (GMT) • Instantiation of abstract format in XML • Why XML? • Supported standard • Built-in representation for hierarchies (nested tags) • Sophisticated linking mechanisms • Can link to points, spans, use explicit locations or tags • XSLT for transduction, XML Schemas for validation, etc. IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
A Few Simple Tags • <struct> • represents a structural node in the annotation • may be recursively nested at any level • <feat> • provides information attached to the node represented by the enclosing<struct> • typeattribute identifies data category • Contents: • string providing a value for the data category • recursively nested<feat>elements (for complex structures) • empty--points via a target attribute to an object in another document IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Other Tags • <alt> • brackets alternative annotations • <rel> • points to a non-contiguous related element • <seg> • points to the data to which the annotation applies • assume the use of stand-off annotation • target attribute uses XML Pointers • <brack> • groups information to be regarded as a unit IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Tag names etc. unimportant • It is the underlying data model that counts • Essentially uses feature structures • GMT sufficiently powerful to represent information across annotation types • Demonstrated applicability to • terminological and lexical information (Ide, et al., 2000) • syntactic annotation (Ide and Romary, 2001) • Existing formats (XML or other) mapped to the GMT for merging, manipulation via common tools, etc.; then re-map to original formats for use in in-house tools and applications. etc. IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Examples • Morpho-syntactic annotation • involves the identification of word classes over a continuous stream of word tokens • may refer to the segmentation of the input stream into word tokens • may also involve grouping together sequences of tokens or identifying sub-token units (or morphemes • description of word classes may include one or several features • syntactic category, lemma, gender, number,… IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Representation in GMT • Single type of structural node • represents a word-level structure unit • One or several information units associated with each structural node IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Pointers to data in primary document Simple Case “Paul aime les croissants” <struct> <struct type=”W-level”> <feat type=”lemma”>Paul</feat> <feat type=”pos”>PNOUN</feat> <seg target=”#w1”/> </struct> <struct type=”W-level”> <feat type=”lemma”>aimer</feat> <feat type=”pos”>VERB</feat> <feat type=”tense”>present</feat> <feat type=”person”>3</feat> <seg target=”#w2”/> </struct> <struct type=”W-level”> <feat type=”lemma”>le</feat> <feat type=”pos”>DET</feat> <feat type=”number”>plural</feat> <seg target=”#w3”/> </struct> <struct type=”W-level”> <feat type=”lemma”>croissant</feat> <feat type=”pos”>NOUN</feat> <feat type=”number”>plural</feat> <seg target=”#w4”/> </struct> </struct> IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Points to “du” in text Gives the structure of the “word” underlying the word Representing More Complex Cases Example: “du” = “de” + “le” in French <struct type=”W-level”> <seg target=”#w1”/> <struct type=”W-level”> <feat type=”lemma”>de</feat> <feat type=”pos”>PREP</feat> </struct> <struct type=”W-level”> <feat type=”lemma”>le</feat> <feat type=”pos”>DET</feat> </struct> </struct> IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
GMT as a Tree Structure Primary Document seg : ….………..…….du…. ……………. …………… ………….. ………… Lemma : de Pos : prep Lemma : le Pos : det IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Primary lemma Component lemmas Compound Words Example: “pomme de terre” <struct type=”W-level”> <feat type=”lemma”>pomme_de_terre</feat> <feat type=”pos”>NOUN</feat> <struct type=”W-level”> <seg target=”#w1”/> <feat type=”lemma”>pomme</feat> <feat type=”pos”>NOUN</feat> </struct> <struct type=”W-level”> <seg target=”#w2”/> <feat type=”lemma”>de</feat> <feat type=”pos”>PREP</feat> </struct> <struct type=”W-level”> <seg target=”#w3”/> <feat type=”lemma”>terre</feat> <feat type=”pos”>NOUN</feat> </struct> </struct> IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Tree Primary Document lemma : pomme_de_terre ….………..…………… Pomme de terre …………… ………….. ………… Seg : Lemma : pomme Pos : noun Seg : Lemma : de Pos : prep Seg : Lemma : terre Pos : noun IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Advantages • Enables specification of the required level of granularity • granularity of the segmentation in (or associated with) primary data may not correspond to that required for the annotation • Can define relations over the tree independently • Compositional for morpho-syntax, syntax, etc. • Partitions in lexical data • … IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
<struct> • <feat type=“orth”>overdress</feat> • <struct> • <feat type=“pos”>verb</feat> • <feat type=“pron”>[jdciw]</pron> • <feat type=“def”> To dress (oneself or another) • too elaborately or finely </feat> • </struct> • <struct> • <feat type=“pos”>noun</feat> • <feat type=“pron”> [masliw]</pron> • <feat type=“def”> A dress that may be wornover • a jumper, blouse, etc.</feat> • </struct> • </struct> Orth : overdress Pron : [jdciw] Pos : verb Def : To dress (oneself or another) too elaborately or finely Pron : [[masliw] Pos : noun Def : A dress that may be worn over a jumper, blouse, etc. IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Alternatives • <struct type=”W-level”> • <seg target=”#w1”/> • <brack> • <alt> • <feat type=”lemma”>boucher</feat> • <feat type=”pos”>VERB</feat> • <feat type=”tense”>present</feat> • <feat type=”confidence”>0.4</feat> • </alt> • <alt> • <feat type=”lemma”>bouche</feat> • <feat type=”pos”>NOUN</feat> • <feat type=”confidence”>0.6</feat> • </alt> • </brack> • </struct> IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Relating Annotation Levels • Three ways: • Temporal anchoring • associates positional information with each structural level • Event-based anchoring • introduces a structural node to represent a location in the text to which all annotations can refer • Object-based anchoring • enables pointing from a given level to one or several structural nodes at another level IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Temporal Anchoring • Positional information • Usually, a pair of numbers expressing the starting and ending point of segment • Attributes for <seg>: • /startPosition/: the temporal or offset position of the beginning of the current structural node; • /endPosition/: the temporal or offset position of the end of the current structural node. • Example: <struct type=”phonetic”> <seg startsAt=”2300” endsAt=”3200”/> <feat type=”phone”>iy</feat> </struct> IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Event-based Anchoring • Useful when: • Not possible/desirable to modify the primary data by inserting markup to identify specific objects or points in the data • Primary data is marked with “milestones” (e.g., time stamps in speech data), where spans across the various milestones must be identified • Here,<struct> elements represent markup for segmentation (e.g., segmentation into words, sentences, etc.). IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
GMT Rendering • Structural node (landmark) referred to by annotations for the defined span <struct type=”landmark”> <seg startsAt=”2300” endsAt=”3200”/> </struct> • Annotation graph formalism explicitly designed for this IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
GMT Advantages • AG formalism reifies the “arc” vs. identification via XML tags • GMT : the two methods are analogous • annotator can use either method • AG not well-suited to hierarchically organized annotations • requires special mechanisms • GMT: exploits the hierarchical structure built in to XML • “flat” and hierarchical annotations treated using the same mechanisms IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Object-based Anchoring • Useful to make dependencies between two or more annotation levels explicit • Example: syntactic annotation can refer directly to the relevant nodes in a morpho-syntactically annotated corpus IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
<!-- Syntactic level (simplified) --> <struct> <feat type=”synCat”>NP</feat> <seg targets=”w3.2 w4”/> </struct> Representation for “du chat” <!-- Morphosyntactic level --> <struct type=”W-level”> <seg target=”#w3”> <struct type=”W-level”> <seg target=”#w3.1”> <feat type=”lemma”>de</feat> <feat type=”pos”>PREP</feat> </struct> <struct type=”W-level”> <seg target=”#w3.2”> <feat type=”lemma”>le</feat> <feat type=”pos”>DET</feat> <feat type=”gender”>masc</feat> </struct> </struct> <struct type=”W-level”> <seg target=”#w4”> <feat type=”lemma>chat</feat> <feat type=”pos”>NOUN</feat> </struct> </struct> IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
GMT as a Modeling Tool • Rendering various formats into GMT representation has revealed some problems, inconsistencies in existing formats • Penn Treebank : inconsistent indication of relations (see Ide and Romary, ACL 2001 or Abeillé Treebank book, forthcoming) • NOMLEX lexicon : no (automatically perceivable) distinction between lists and alternatives • The abstract format serves the unexpected purpose of providing a “template” for fundamental annotation properties IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Jumping Ahead… • Is XML distracting us from our real work? • YES, because • Focus on details of using XML and related standards can obscure the real work of data modeling • BUT • Datas models are no use only in the abstract - need means to implement • XML, schemas, RDF, etc. are powerful data modeling tools based on years of research in this area • Need to know how to best exploit them for our purposes • Need a synergy between modeling efforts and implementation in XML, RDF, etc. • Need to remember that using XML is just a vehicle to ensure flexibility, convertability, and compatibility with evolving technologies IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Conclusion • ISO committee • Work is continually evolving • Try to stay at the leading edge of data representation • We are only at the “assembly language” level • We need to do this right to enable a “web of databases” • Call for participation!!! IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia
Thank You Contacts US Expert, ISO TC37 SC4 Nancy Ide ide@cs.vassar.edu Chairman, ISO TC37 SC4 Laurent Romary romary@loria.fr IRCS Workshop on Linguistic Databases • 11-13 December 2001 • Philadelphia