Qualitative Linguistic Terms and Geographic Concepts

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Abstract Definitions of categories in existent geospatial ontologies are an invaluable. source of information because they provide us with essential knowledge about concepts and. their properties A closer examination reveals that definitions also contain supplementary. linguistic items which are mainly qualitative expressions such as quantifiers This. inclusion of modifiers in definitions affects the way values are assigned to the categories. properties semantic properties and relations This paper introduces a methodology for a. representing the essence of qualitative information to clarify the identity relations among. categories and b assessing their semantic similarity in order to disambiguate the. taxonomic structure of existent geospatial ontologies. 1 Introduction, To what extent structures and transport networks must cover a land so that it qualifies. as a member of category Continuous Urban Fabric For how long must an area be. covered by water to qualify as a member of category Swamp According to CORINE. LC 2000 a land cover nomenclature in Continuous Urban Fabric most of the land is. covered by structures and the transport network According to DIGEST 2000 a. Swamp is a low lying saturated area covered with water all or most of the year These. definitions do not provide a straightforward answer to the problem of category. membership as depicted from the questions hereinabove not to mention that the use of. vague linguistic terms such as quantifiers complicates ontological analysis. In this paper we introduce a methodology for modeling Qualitative Linguistic Terms. QLTs which can be found in definitions of categories in existing geospatial. ontologies According to Guarino 2002 an ontology is a shared vocabulary and a. specification of its intended meaning Ontologies may differ in complexity and. formality and can range from lightweight a simple glossary of terms to heavyweight. axiomatized formal ones Fonseca and Martin 2004 advocate that the design of. information system ontologies must be aided by hermeunetic analysis while Smith. 2003 argues that the construction of robust ontologies has to involve. conceptualizations transparent to reality that is Science should not exclude common. sense In our case the ontologies that we analyze are taxonomies and terminological. ones where categories are described by an agreed shared lexicon Richer ontologies than. those examined herein are not common in the GIS community however when new. geospatial ontologies are to be generated several tenets should be followed as discussed. by Tomai and Kavouras 2004, Prior work by Kokla and Kavouras 2002 and Tomai and Kavouras 2003 has focused. on the determination of the semantic properties and relations from such definitions. Semantic properties and relations can be considered as the combination of a properties. of the categories and b values for these properties The problem with QLTs is that they. affect property values in a non straightforward manner The present analysis underlines. the need to set the values of properties in a clear cut way therefore to explicitly define. the semantics semantic relations and properties of geospatial concepts. Hence the objective of the research is to explore ways of assigning numeric values to. qualitative linguistic terms which can be found in definitions of geospatial concepts. and to further use these values when determining similarity among these concepts The. intention is to model these qualitative linguistic terms in a way to formally express the. semantics of the geospatial concepts definitions The current research consists in the. clarification of the identity relationships of geospatial categories and the disambiguation. in the taxonomic structure of existing ontologies The straightforward establishment of. properties for geospatial categories facilitates any integration procedure In addition the. modeling of modifiers accounts better for the semantic similarity of the categories since. it reveals subtle dissimilarities among them, More specifically the next section of this paper deals with theoretical matters of. qualitative linguistic expressions found in definitions Firstly we defend the use of. definitions in the process of educing semantic relations and we identify the types of the. included qualitative linguistic terms The focus of the paper is to analyze and model the. category of modifiers called Generalized Quantifiers referred to as quantifiers. hereinafter, We examine four existent geospatial ontologies categorizations the European s. Environmental Agency s CORINE LC 2000 DIGEST 2000 the American National. Standard SDTS 1997 and GMap 2000 all of which contain definitions of. geographic categories The third section of the paper details the characteristics of the. examined categorizations and provides information on the included quantifiers. In section four we present a methodology for turning qualitative expressions into. quantitative information which can be farther applied to establish similarity among. categories In this analysis we employ the classic linguistic theory of Generalized. Quantifiers and methods from the field of computational linguistics which can. represent QLTs schematically and are used to assess QLT similarity Section 5 gives a. practical account of the results of the methodology while the last section summarizes. the method presented herein and sets the ground for further research. 2 Definitions and Qualitative Linguistic Terms, A survey of existing definitions of categories in geospatial ontologies shows that they.
contain significant lexical knowledge From this information we can determine. semantic relations and properties for the geographic categories However an extensive. examination of these definitions shows that they also include qualitative linguistic terms. and expressions which work as degree modifiers on the semantics of geographic. 1 2 1 Defending the Use of Definitions, At this point it is important to defend the value of definitions in geospatial ontologies. Linguists have not always shown full appreciation for definitions and the fact remains. that lexicography s definitions have many deficiencies In our case nevertheless. definitions contribute to ontological research since they usually are the only source of. information about the concepts described by the geospatial ontologies categorizations. What is more definitions contain organized knowledge about the terms they describe. knowledge that can be extracted analyzed and formalized According to the Cambridge. International Dictionary of English 2001 A definition is a statement that explains the. meaning of a word or phrase, Therefore a definition is considered as highly structured text rich in the following. types of knowledge as defined by the participants of SIGLEX workshop in Barriere. Lexical Knowledge rich semantic structure associative patterns between words. feature structure,World Knowledge ontology organization of concepts. Semantic Knowledge word sentence text meanings predicates. In the case of analyzing concepts of a particular domain such as the geospatial domain. definitions are rich also in,Domain Specific Knowledge of a particular domain. Pragmatic Knowledge information coming from context. Many attempts such as these by Barriere 1997 and van der Wende 1995 have. focused on extracting semantic relations from larger lexical databases such as. dictionaries under the axiom that the language used in dictionary definitions presents. syntactic patterns syntactic structure of a definition to express these relations Most of. that research is conducted following the genus differentia type of definition This kind. of approach results in building a taxonomy the is a hierarchy based on the genus. Another approach can be found in WordNet 2 0 2003 Significant relations for the. structure of this lexical database are as discussed by Miller 1990 synonymy. antonymy hyponymy hypernymy meronymy and holonymy,2 2 2 Qualitative Linguistic Terms.
Previous work by Kavouras et al 2003 Kokla and Kavouras 2002 Tomai and. Kavouras 2003 has introduced the determination of semantic relations for geospatial. categories from their definitions using techniques of Natural Language Understanding. While in NLU much research has been conducted in the direction of nouns as in van. der Wende 1995 and verbs as in Fellbaum 1990 their modifiers have not yet been. explored to such an extent,Modifiers can be, Nouns functioning as adjectives called nominals e g water transportation For. reasons of simplicity we use the term nominals for expressions consisting of a. head noun preceded by one or more noun specifiers, Adjectives that modify a noun assigning an attribute to it e g brackish water These. are also nominals but one or more adjective specifiers precede the head noun. Adverbs that modify verbs adjectives or other adverbs e g frequently includes. very large quite often, The first two kinds of modifiers can be distinguished from the third and are classified as. qualifiers while the third is mostly referred to as adverbial qualifier. Definitions for geospatial categories include but to a lesser extent another category of. words that are categorized as quantifiers Quantifiers in logic correspond to for. all and exists In Natural Language however a small category of words. correspond to how quantifiers act in logic Examples of this category are all each. every some most many and several, The existence of such words both qualifiers and quantifiers in definitions of geospatial. categories necessitates their modeling when educing semantic relations since the. assignment of their numeric values is not straightforward Therefore modifiers and. quantifiers do not make explicit the properties involved A skeptic would state at this. point that QLTs present a deficiency of definitions for they do not add to meaning on. the contrary they are futile verbal forms An immediate reply to such a position is that. QLTs are used widely in definitions with the purpose to differentiate concepts. Furthermore conducting a definitions analysis using the bag of words approach1 and. therefore disregard certain aspects of qualitative information imposes restrictions on. conveying meaning, This paper focuses on modeling Generalized Quantifiers in definitions of geographic.
concepts and establishes similarity among these linguistic terms. 3 Geographic Categorizations Analyzed, As mentioned above we analyze four 4 ontologies categorizations of geospatial. information These are CORINE Land Cover 2000 DIGEST 2000 SDTS 1997. 1 The bag of words approach is a non syntactic based approach of information retrieval since word order and. hierarchical relations are ignored Each item is considered independently regardless of syntactic relation e g house. representative vs representative house are considered related in such an approach Klavans et al 1997. and GMap 2000 All these categorizations include definitions of geospatial concepts. The majority of these definitions are simple complete sentences. WordNet version 2 0 could have been also included in the analysis The reason for not. doing so is that we wanted to keep this analysis to a limited size of entries As it will be. shown in the next section the ontologies used have a limited number of categories. which are to a certain extent manageable Another problematic aspect of using a lexical. database such as WordNet is that like all dictionaries it favors polysemy On the. other hand the selected ontologies describe each category univocally that is they only. deal with one sense of the given term which is an advantage in our case Furthermore. the abovementioned categorizations provide information of a given domain the. geographic one while WordNet is not domain dependent. 3 3 1 Characteristics of the Examined Ontologies, This section presents in brief the characteristics of the four ontologies. CORINE Land Cover is a categorization schema that was established to provide. consistent information about land cover for the member states of the EU It has a. three level hierarchical structure and includes 44 category terms at the lowest level. DIGEST is an international exchange standard that has been designed to enable the. transfer of Digital Geographic Information DGI between geographic information. systems The FACC Feature and Attribute Coding Catalogue contains features. attributes and attribute values The features of the FACC are organized in 10. categories which are further divided in subcategories. The Spatial Data Transfer Standard SDTS gives definitions of spatial features for. data transfer These are described by the concepts Entity Type Entity Instance. Attribute and Attribute Value and by the terms Standard and Included The. standard describes 200 entity types and has no hierarchical structure. GMap established in 2000 contains specifications of spatial data The Global Map. Data Dictionary has specifications for vector and raster data. 4 3 2 Qualitative Linguistic Terms in Definitions The case of Quantifiers. Quantifiers present a small linguistic category in Natural Language The category. consists of words that indicate quantity which range from all to no A quantifier. included in a geographic definition is shown by the following example. 1 Swamp A low lying saturated area covered with water all or most of the year. where accumulating dead vegetation does not rapidly decay DIGEST. Qualitative Linguistic Terms and Geographic Concepts Quantifiers in Definitions Eleni Tomai and Marinos Kavouras Cartography Laboratory School of Rural and Surveying Engineering National Technical University of Athens etomai mail ntua gr mkav survey ntua gr Short Title Quantifiers in geographic definitions Keywords

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