Pattern for Re-engineering a Term-based Thesaurus, Which Follows the Record-based Model, to a Lightweight Ontology

Abstract

This pattern for re-engineering non-ontological resources (PR-NOR) fits in the Schema Re-engineering Category proposed by [3]. The pattern defines a procedure that transforms the term-based thesaurus components into ontology representational primitives. This pattern comes from the experience of ontology engineers in developing ontologies using thesauri in several projects (SEEMP1, NeOn2, and Knowledge Web3). The pattern is included in a pool of patterns, which is a key element of our method for re-engineering non-ontological resources into ontologies [2]. The patterns generate the ontologies at a conceptualization level, independent of the ontology implementation language.

Introduction

Problem

Re-engineering a term-based thesaurus, which follows the record-based model, to design a lightweight ontology. A non-ontological resource holds a term-based thesaurus which follows the record-based model. A thesaurus represents the knowledge of a domain with a collection of terms and a limited set of relations between them.

The record-based data model [ 4 ] is a denormalized structure, uses a record for every term with the information about the term, such as synonyms, broader, narrower and related terms. 1 http://www.seemp.org 2 http://www.neon-project.org 3 http://knowledgeweb.semanticweb.org

Applicability

The semantics of the relation between narrower and broader terms are subClassOf.

ti 2.4. Identify the thesaurus term, tr , which are related terms of ti. They are referenced in the same record that contains ti. 2.5. For each one of the above identified the

saurus term tr : 2.5.1. Create the corresponding ontology class, Cr class, if it is not created yet. 2.5.2. Set up the relatedClass relation be

tween Cr and Ci 2.5.3. Repeat from step 2.4 for tr as a new

ti 2.6. Identify the thesaurus term, tq , which are equivalent terms of ti. They are referenced in the same record that contains ti. 2.7. For each one of the above identified the

saurus term tq : 2.7.1. Apply the SynonymOrEquivalence

(SOE) pattern.

Example

Suppose that someone wants to build a lightweight ontology based on the European Training Thesaurus (ETT), which is a term-based thesaurus and it follows the record-based model. The European Training Thesaurus (ETT) constitutes the controlled vocabulary of reference in the field of vocational education and training (VET) in Europe. The relation semantics between the sub-ordinate and the super-ordinate concepts is subClassOf. This classification scheme is available at http://libserver.cedefop.europa.eu/ett/en/

Ontology Generated

The ontology generated will be based on the lightweight ontology architectural pattern (APLW-01) [ 5 ].

Each thesaurus term is mapped to a class. A subClassOf relation is defined between the new classes for the BT/NT relation. A relatedClass relation is defined between the new classes for the RT relation. For the UF/USE relations the SynonymOrEquivalence (SOE) pattern [ 1 ] is applied.

Related Resources

This pattern is related to the architectural pattern AP-LW-01 [ 5 ] for modelling a lightweight ontology. This pattern is being applied to re-engineer the European Training Thesaurus (ETT)4 into a Education Ontology5, within the context of the SEEMP project. It contains over 2500 terms (1550 are descriptors, and 950 non descriptors). This term-based thesaurus is modelled following the record-based data model. 4

Summary and Future Work

We have presented a pattern for transforming a term-based thesaurus, which is modelled following a record-based data model, into a lightweight ontology. The pattern is included in a pool of patterns, which is a key element of our method for re-engineering non-ontological resources into ontologies [ 2 ].

We plan to develop software libraries within a framework that implement the transformation process suggested by the pattern. Moreover, we will include external resources to improve the quality of the resultant ontologies. Finally, we need to calculate how much effort do we save re-engineering classification schemes using patterns compared with re-engineering classification schemes without them. Acknowledgments. This work has been partially supported by the European Comission projects NeOn(FP6-027595) and SEEMP(FP6-027347), as well as by an R+D grant from the UPM. 4 http://libserver.cedefop.europa.eu/ett/en/ 5 The ontology will be available at http://droz.dia.fi.upm.es/hrmontology/

References

1. C. Roussey and O. Corcho. SynonymOrEquivalence (SOE) Pattern . http://ontologydesignpatterns.org, 2009 .

2. A. Garc ´ıa, A. G´omez-P´erez , M. C. Su´arez- Figueroa , and B. Villaz ´on-Terrazas. A Pattern Based Approach for Re-engineering Non-Ontological Resources into Ontologies . In Proceedings of the 3rd Asian Semantic Web Conference (ASWC2008) . Springer-Verlag, 2008 .

3. V. Presutti , A. Gangemi , S. David , G. Aguado de Cea, M. C. Surez-Figueroa , E. Montiel-Ponsoda , and M. Poveda. NeOn Deliverable D2.5.1. A Library of Ontology Design Patterns: reusable solutions for collaborative design of networked ontologies . In NeOn Project . http://www.neon-project.org, 2008 .

4. D. Soergel . Data models for an integrated thesaurus database . Comatibility and Integration of Order Systems , 24 ( 3 ): 47 - 57 , 1995 .

5. M. C. Su´arez- Figueroa , S. Brockmans , A. Gangemi , A. G´omez-P´erez , J. Lehmann, H. Lewen , V. Presutti , and M. Sabou . Neon modelling components . Technical report, NeOn project deliverable D5.1.1 , 2007 .