Kornelije Rabuzin

Data Warehouses and Business Intelligence in Croatia: Do Managers Know How to Use Them?

Authors of this paper were directly involved in several data warehousing and business intelligence projects that were carried out in companies in Croatia. Based on the experience from those projects, this paper presents how those solutions were implemented — and more importantly, how they were used by managers at different levels of management. Three different companies are described, including three different implemented solutions. One company was small, one was mid-sized and one was large. All had differences in ownership and education level of managers. Implementation (technical) details are omitted, but this paper shows that managers do not always see what business intelligence can do. Furthermore, it is shown that such projects do not always have to be expensive. KeyWoRDS Business Intelligence, Data Warehouses, Databases, Managers

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.

Fuzzy active rules in mutimodal biometric systems

This paper presents the idea how to use fuzzy active rules within biometric systems. We have already shown how the concept of complex events presented in the active database theory could be used in order to build a biometric system. We especially explored the paradigm of active rules and complex events and experimental results were encouraging. Fuzzy logic is very good when dealing with imprecision and uncertainty and hence it is suitable to be used in biometric systems. We will discuss how to apply fuzzy active rules in order to deal with imprecise decision making in multimodal biometric systems.

A taxonomy of biometric methods

In this paper we shall introduce a taxonomy of biometric methods continuing thereby our previous research on selected segments of biometrics. We show how our previously developed systematization and categorization of biometric methods, characteristics and models can be extended by building upon an open ontology of biometrics. The developed taxonomy inherits its openness and extendibility as well as its consistency from the systematization, adding new insights at the same time. We add a new dimension, namely biometric samples, to our previous framework built upon biometric characteristics as well as the general biometric system developed by Wayman and extended in our research.

The Concept of Complex Events as Suitable Means for Biometric System Implementation

Generally speaking, a user (person) can be authorised in three different ways (or their combinations): one can use something that a user knows, something that a user possesses or by measuring some physical or psychological characteristics which are immanent and unique to each person i.e. biometric characteristics. In this paper we are going to put accent on this third possibility. We are going to show how active databases could be used in order to implement multimodal biometric systems, and, due to some capabilities which they possess, reduce the time needed for authorisation (identification). Especially, we will put accent on complex events and show how they can be used for identification (authorisation) purposes.

Prototype of a Web ETL Tool

Extract, transform and load (ETL) is a process that makes it possible to extract data from operational data sources, to transform data in the way needed for data warehousing purposes and to load data into a data warehouse (DW). ETL process is the most important part when building the data warehouse. Because the ETL process is a very complex and time consuming, this paper presents a prototype of a web ETL tool that offers step-by-step guidance through the entire process to the end user. This ETL tool is designed as a web application so users can save time (and space) required for installation purposes.

Extending Trigger-by-Example Approach to Support Time Events

An interesting type of objects in the SQL standard and database systems are triggers which are nowadays being widely used. The capability of automatic reaction to certain events is of great importance. Although the idea of triggers seems very promising, their complexity and variety of different programming languages used for their implementation hinder their wider use. To write more complex triggers becomes a difficult task and new methods for easier implementation are required. An interesting approach to resolve this flaw was already presented, so called Trigger-By-Example approach; in this paper we extend this idea in a way that triggers based upon time events are supported too i.e. that triggers based on time events can be built automatically in a specified database management system. The paper will explain the idea and show how this was done in PostgreSQL database management system.

RDF Means Database

Graph databases are continuously rising in popularity, as well as other types of NoSQL databases. RDF databases, as a type of graph databases are also starting to grow in popularity, but are still very little used. There are many discussions about advantages of various types of databases one over another. This paper focuses on RDF databases and their potential. Comparison of systems that support RDF model and those that support graph databases only with property graph model is performed according to several important characteristics. Results show similarities and differences in their support for database management.

Deductive Graph Database -- Datalog in Action

In recent years many NoSQL systems, including graph databases, have become available. For large amounts of interconnected data, these systems represent a good choice. Deductive databases have been used in order to deduce new pieces of information based on a database that containes large amounts of data. But it is important to keep in mind that such databases were mostly relational, i.e., relations were used to store data upon which deductive mechanisms were used. In this paper, deductive graph databases are proposed. In deductive graph databases, data are stored in a graph database, and Datalog is used for reasoning purposes on a relational representation of a graph database.

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.