Alen Lovrenčić

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.

Detecting computer code plagiarism in higher education

Rapid development of industry and economy requires quick and efficient education of large amount of theoretical knowledge and practical skills. In computer science, especially in programming, this trend is very noticeable and real experts are needed and hard to create. But new problem has emerged in higher education and its name is plagiarism. In order to prevent this one would have to check all students program codes to find similarities. To do this efficiently a procedure has been designed upon which a certain prototype was developed and tested. We discuss efficiency of this solution and we also mention some other methods and algorithms. We also discuss some other possible usages of this solution and we mention further actions and steps in our research.

In search of an improved BoM and MRP algorithm

In facing the problem of building a complex yet fast and resource efficient Enterprise Resource Planning (ERP) or Extended Resource Planning (XRP) system the first obstacle is the creation of a Bill of Materials (BoM) algorithm, which is used to calculate material needs according to the production plan. Taking into consideration different possibilities of BoM implementation, we compared linked lists, tree structure and matrix implementation in relation to algorithm complexity. As we came to the conclusion that none of them suits the needs of modern systems, we proposed a new BoM algorithm called multiple linked list implementation. It combines the advantages of other implementations with a new approach based on two complex data structures used to represent both the data and relationships between products, parts or components used in production.

Mind map generator software

In our previous research we have made literature analysis and discovered possible mind map application areas. We have pointed out why currently developed software and methods are not adequate and why we are developing a new one. We have defined system architecture and functionality that our software would have. After that, we proceeded with text-mining algorithm development and testing after which we have concluded with our plans for further research. In this paper we will give basic notions about previously published article and present our custom developed software for automatic mind map generation. This software will be tested. Generated mind maps will be critically analyzed. The paper will be concluded with research summary and possible further research and software improvement.

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.

More general minimum feedback arc set: Statistically defining information system digraph

When information system is being designed we have to determine, in some way, a sequence/priority of development of its subsystems. There are many algorithms that can be immediately applied or modified to solve previously mentioned problem. Nevertheless, they have all been tested on randomly generated graphs which in certain cases may or may not represent real information systems that can be found in practical situations. Therefore, in this paper we have statistically defined general digraph that represents real-world information systems. This definition can potentially lead to finding better algorithms for automatic or semiautomatic development and design of information systems.