Mirko Čubrilo

Modelling Functional Dependencies in Databases using Mathematical Logic

For more than 20 years relational model is the most important database model. So, it is examined in the most various ways. A very important concept in the relational model is the concept of dependencies, especially functional dependencies. It is proven that functional dependencies can be represented by formulae of prepositional or predicate calculus. There are several systems of transforming functional dependencies into a logic system, known from the literature, but all of them has one serious drawback: they do not have a form that is appropriate for reasoning about normalization. This paper presents a new approach to the process of transforming functional dependencies into predicate calculus. The system presented in this paper is designed in the way to be appropriate for normalization, reasoning about it, as well as for the building a system for automated normalization of databases.

Resolving Physical Conflicts in Multiagent Systems

During the project we were working on physical conflicts occurred in a multiagent system. In order to resolve the problem many different conflict resolution strategies were examined and many proposed solutions found. In this paper we explore conflicts as well as their causes and possible solutions. Based upon this research we implemented a centralized solution and added a reactive agent in the database in order to avoid conflict situations and efficiently allocate a set of resources.

University Studies Ontology-Domain Modeling

Ontologies are nowadays one of the most popular and widespread means of knowledge representation. They are also considered as a basis for new technologies of Semantic Web. Web ontologies are being developed mostly in OWL, a language whose one part is based on description logics. Since one of the steps in ontology development is domain modeling, it would be favorable to create a domain model exactly by means of description logic. Such an example of a university studies in Croatia domain modeling is presented in this paper.

Semantic Web data integration using F-Logic

The paper addresses data integration for heterogeneous knowledge sources in the semantic Web domain. The objective of the works is to show that logic programming languages with second order syntax and with object oriented approach (HiLog+F-logic) provide adequate support for a data integration system. In particular, object oriented approach supporting the F-logic language provides a natural translation and manipulation of Web data. The paper describes elements relevant for the development of semantic Web applications. Activities of data integration process are explained through the example of an application developed for a specific domain, searching data about scientific conferences

Incorporating infatuation in Multi-Agent Systems

In this paper infatuation property in multi-agent systems is described. Modal operators for positive infatuation (focusing on a single attractive or desirable characteristic of another agent and then considering the total agent as that one positive characteristic) as well as negative infatuation are defined. Some relationships between the infatuation operators and usual logic operators are characterized.

Logical Consequences in Partial Knowledge Bases

In this paper, we consider logical consequences for reasoning about functional, multivalued, and join dependencies in partial knowledge bases. The standard consequence, strong consequence, and the weak consequence are characterized. We prove that reasoning based on the standard logical consequence is equivalent to reasoning based on the strong logical consequence. In addition, we prove that reasoning based on the standard logical consequence and reasoning based on the weak logical consequence are not equivalent. We also define a formal system FSED for reasoning about existence dependencies. We prove that the formal system FSED is sound and complete. We state the connection between existence and functional dependencies: reasoning about existence dependencies based on the corresponding logical consequence and reasoning about functional dependencies based on the standard logical consequence are equivalent.

F-Logic Data and Knowledge Reasoning in the Semantic Web Context

The paper addresses problems of data and knowledge reasoning in the domain of Semantic Web. The objective of this research was to explore object-oriented logic program languages in the light of Semantic Web concept. It will be shown that logical formalisms integrating the deductive component and the object-oriented approach and featuring the second-order syntax and the first-order semantics provide an adequate Web data representation and reasoning. The paper describes elements relevant for the development of Semantic Web applications. Activities of data integration process are explained through the example of an application developed for a specific domain, searching data about scientific conferences.

Reasoning About Knowledge using Lattices and F-logic

The paper describes knowledge reasoning using lattices in F-logic. The objective of this paper is to show that logic programming languages with second order syntax and with object oriented approach (HiLog + F-logic) provide adequate support for lattice representation and manipulation. A description on how lattices can be represented using F-logic formalism and some important rules for lattice manipulation are given. The theory of formal concept analysis is examined The basic concepts are described and represented in F-logic. Rules necessary for generating the concept lattice are presented. Further, examples of lattice application for knowledge reasoning are described as reasoning about semantic context and concept analysis for query modification.