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Abstract

The paper analysed here is a kind of position paper. In order to get a better under-standing of the reported work I used the retrieval interface of the thesaurus, the so-called NCI DTS Browser accessible via the Web3, and I perused the cited OWL file4 with numerous "Find" and "Find next" string searches. In addition the file was im-ported into Protégé 2000, Release 2.0, with OWL Plugin 1.0 and Racer Plugin 1.7.14. At the end of the paper's introduction the authors say: "In the following sections, this paper will describe the terminology development process at NCI, and the issues associated with converting a description logic based nomenclature to a semantically rich OWL ontology." While I will not deal with the first part, i.e. the terminology development process at NCI, I do not see the thesaurus as a description logic based nomenclature, or its cur-rent state and conversion already result in a "rich" OWL ontology. What does "rich" mean here? According to my view there is a great quantity of concepts and links but a very poor description logic structure which enables inferences. And what does the fol-lowing really mean, which is said a few lines previously: "Although editors have defined a number of named ontologic relations to support the description-logic based structure of the Thesaurus, additional relation-ships are considered for inclusion as required to support dependent applications."
According to my findings several relations available in the thesaurus query interface as "roles", are not used, i.e. there are not yet any assertions with them. And those which are used do not contribute to complete concept definitions of concepts which represent thesaurus main entries. In other words: The authors claim to already have a "description logic based nomenclature", where there is not yet one which deserves that title by being much more than a thesaurus with strict subsumption and additional inheritable semantic links. In the last section of the paper the authors say: "The most time consuming process in this conversion was making a careful analysis of the Thesaurus to understand the best way to translate it into OWL." "For other conversions, these same types of distinctions and decisions must be made. The expressive power of a proprietary encoding can vary widely from that in OWL or RDF. Understanding the original semantics and engineering a solution that most closely duplicates it is critical for creating a useful and accu-rate ontology." My question is: What decisions were made and are they exemplary, can they be rec-ommended as "the best way"? I raise strong doubts with respect to that, and I miss more profound discussions of the issues at stake. The following notes are dedicated to a critical description and assessment of the results of that conversion activity. They are written in a tutorial style more or less addressing students, but myself being a learner especially in the field of medical knowledge representation I do not speak "ex cathedra".

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Abstract

T.2: The ability to identify and locate relevant information among vast collections and other resources is a major and pressing challenge today. Several different types of vocabulary are in use for this purpose. Some of the most widely used vocabularies were designed a hundred years ago and have been evolving steadily. A different generation of vocabularies is now emerging, designed to exploit the electronic media more effectively. A good understanding of the previous generation is still essential for effective access to collections indexed with them. An important object of ISO 25964 as a whole is to support data exchange and other forms of interoperability in circumstances in which more than one structured vocabulary is applied within one retrieval system or network. Sometimes one vocabulary has to be mapped to another, and it is important to understand both the potential and the limitations of such mappings. In other systems, a thesaurus is mapped to a classification scheme, or an ontology to a thesaurus. Comprehensive interoperability needs to cover the whole range of vocabulary types, whether young or old. Concepts in different vocabularies are related only in that they have the same or similar meaning. However, the meaning can be found in a number of different aspects within each particular type of structured vocabulary: - within terms or captions selected in different languages; - in the notation assigned indicating a place within a larger hierarchy; - in the definition, scope notes, history notes and other notes that explain the significance of that concept; and - in explicit relationships to other concepts or entities within the same vocabulary. In order to create mappings from one structured vocabulary to another it is first necessary to understand, within the context of each different type of structured vocabulary, the significance and relative importance of each of the different elements in defining the meaning of that particular concept. ISO 25964-1 describes the key characteristics of thesauri along with additional advice on best practice. ISO 25964-2 focuses on other types of vocabulary and does not attempt to cover all aspects of good practice. It concentrates on those aspects which need to be understood if one of the vocabularies is to work effectively alongside one or more of the others. Recognizing that a new standard cannot be applied to some existing vocabularies, this part of ISO 25964 provides informative description alongside the recommendations, the aim of which is to enable users and system developers to interpret and implement the existing vocabularies effectively. The remainder of ISO 25964-2 deals with the principles and practicalities of establishing mappings between vocabularies.

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Abstract

This document describes in brief how to express the content and structure of a thesaurus, and metadata about a thesaurus, in RDF. Using RDF allows data to be linked to and/or merged with other RDF data by semantic web applications. The Semantic Web, which is based on the Resource Description Framework (RDF), provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries.

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Abstract

The ISO 2788 guidelines for monolingual thesauri contain a differentiation of "the hierarchical relationship" into "generic", "partitive", and "instance", which, for purposes of document retrieval, was deemed adequate. However, ontologies, designed as language inventories for a wider scope of knowledge representation, are based on all these and some more logical differentiations. Rereading the ISO 2788 standard and inspecting the published Cyc Upper Ontology, it is argued that the adoption of the document-retrieval definition of subsumption generally prevents the conception or use of a thesaurus as a substructure of an ontology of the new kind as constructed for AI applications. When a thesaurus is used for fact description and inference on fact descriptions, the instance-of relationship too should be reconsidered: It may also link concepts and metaconcepts, and then its distinction from subsumption is needed. The treatment of the instance-of relationship in thesauri, the Cyc Upper Ontology, and WordNet is described from this perspective

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Abstract

This paper presents an overview of the work in progress at the W3C to produce a standard conversion of WordNet to the RDF/OWL representation language in use in the SemanticWeb community. Such a standard representation is useful to provide application developers a high-quality resource and to promote interoperability. Important requirements in this conversion process are that it should be complete and should stay close to WordNet's conceptual model. The paper explains the steps taken to produce the conversion and details design decisions such as the composition of the class hierarchy and properties, the addition of suitable OWL semantics and the chosen format of the URIs. Additional topics include a strategy to incorporate OWL and RDFS semantics in one schema such that both RDF(S) infrastructure and OWL infrastructure can interpret the information correctly, problems encountered in understanding the Prolog source files and the description of the two versions that are provided (Basic and Full) to accommodate different usages of WordNet.

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Date

26. 1.2011 20:55:02

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Date

26.12.2011 13:22:07