Research on ontology is becoming increasingly widespread in the computer science community, and its importance is being recognized in a multiplicity of research fields and application areas, including knowledge engineering, database design and integration, information retrieval and extraction. We shall use the generic term information systems, in its broadest sense, to collectively refer to these application perspectives. We argue in this paper that so-called ontologies present their own methodological and architectural peculiarities: on the methodological side, their main peculiarity is the adoption of a highly interdisciplinary approach, while on the architectural side the most interesting aspect is the centrality of the role they can play in an information system, leading to the perspective of ontology-driven information systems.

The purpose of this paper is to explore some semantic problems related to the use of linguistic ontologies in information systems, and to suggest some organizing principles aimed t o solve such problems. The taxonomic structure of current ontologies is unfortunately quite complicated and hard to understand, especially for what concerns the upper levels. I will focus here on the problem of ISA overloading, which I believe is the main responsible of these difficulties. To this purpose, I will carefully analyze the ontological nature of the categories used in current upper-level structures, considering the necessity of splitting them according to more subtle distinctions or the opportunity of excluding them because of their limited organizational role.

The task of information extraction can be seen as a problem of semantic matching between a user-defined template and a piece of information written in natural language. To this purpose, the ontological assumptions of the template need to be suitably specified, and compared with the ontological implications of the text. So-called "ontologies", consisting of theories of various kinds expressing the meaning of shared vocabularies, begin to be used for this task. This paper addresses the theoretical issues related to the design and use of such ontologies for purposes of information retrieval and extraction. After a discussion on the nature of semantic matching within a model-theoretical framework, we introduce the subject of Formal Ontology, showing how the notions of parthood, integrity, identity, and dependence can be of help in understanding, organizing and formalizing fundamental ontological distinctions. We present then some basic principles for ontology design, and we illustrate a preliminary proposal for a top-level ontology develped according to such principles. As a concrete example of ontology-based information retrieval, we finally report an ongoing experience of use of a large linguistic ontology for the retrieval of object-oriented software components.

When modelling a domain, it is often the case that certain individuals are represented as belonging to multiple categories, generating therefore "tangled " hierarchies: 1. A physical object can be seen as an amount of matter 2. A hole can be seen as a region of space

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Abstract. We have systems rich in information but poor in knowledge. The paper shall sketch a framework in which information and knowledge could be properly integrated. Our initial hypothesis is that passing from information to knowledge involves the elaboration of a well structured theory of semiotic units. The latter is

It is plain that the problem of the levels or layers of a work of art is an important part of any theory of the aesthetic object. In other words, what I wish to state clearly from the outset is that of the two components that select the field of interest – that of the object, and that of its aesthetic valence – reference to the object arranges reference to its aesthetic valence. Put otherwise, the theme of the aesthetic object is a particular subdivision of ontology – a subdivision, moreover, which may prove fundamental, shedding light on several aspects of the overall framework of ontology. This was pointed by Nicolai Hartmann, when in the introduction to Zur Grundlegung der Ontologie – one of his main ontological works – he asserted that “the problematic [of art] belongs to the area of problems in which the ontological problem is rooted. ” Evidently, when matters are viewed from this point of view, that part of aesthetics which addresses the problem of the aesthetic object may yield results of relevance to more general ontological reflection as well. Complementary to investigation by objects is investigation by acts. In this

The conception of time depends on the socio-cultural context; therefore there are variable understandings of the concept time. As a result, communication problems between people arise. In a dynamic and multi-cultural environment like the Web, where both billions of people with different socio-cultural contexts and numerous context dependent software applications interact, similar communication and inter-operability problems occur. Such problems can be avoided, if socio-cultural temporal information is described in an explicit, unambiguous and machine processable manner. This way, heterogeneous temporal Web application systems can share the same information, thus the same conception of time. In literature, Web ontologies are regarded as means to explicate knowledge and provide consensus about a given domain. This thesis first explores the domain of ontological engineering. Second, it devises the ontology, formalized in OWL, to explicate the conception of socio-cultural time. Expressions and concepts of socio-cultural time comprise the subject of the ontological model. This model is used to form the foundation of a sociocultural calendar for the Web and to describe how a Web based automated appointment scheduling service provides more context sensitive service to its users, by deploying the ontological model and the socio-cultural Web calendar.