Volume 4, Issue 3

Category is a mathematical structure consisting of objects and morphisms between objects with some specific properties. Categories examine in abstract way the properties of particular mathematical concepts by formalizing them as collections of objects and morphisms. Categorical structures are widely used in computer science for exact mathematical modeling. This paper highlights the most typical use of categories for constructing the model of part of differential calculus by using special category named arrow category; and codomain and domain functors.

Popularity of domain-specific languages brings the problem of language components reuse. It should be possible to use parts of different languages in development of new one to lower costs and also allow incremental development. This problem could be solved using the composition of languages. In this paper we discuss the view of language composition from the perspective of concepts composition, where the role of concrete syntax is lowered. We present examples of language composition based on the principles of object composition implemented using YAJCo parser generator, that allows to specify the language based on its abstract syntax.

Ray tracing is one of computer graphics methods for achieving the most realistic outputs. Its main disadvantage is high computation demands. Removal of this disadvantage is possible using parallelization due to the fact that the ray tracing method is inherently parallel. Solution presented in this article uses GPGPU (general-purpose computing on graphics processing units) technology and a predictive evaluation for the acceleration of ray tracing method. The CUDA C was selected as a GPGPU language and it was used for a conversion of a raytracer core. The main reason for choosing this language was usage of the Tesla C1060 graphics card. The predictive evaluation of a scene was based on the fact that total computation time increases proportionally with resolution. This evaluation allows selection of the optimal scene division for the parallel ray tracing. In tests, proposed GPGPU solution reached accelerations up to 28.3× comparing to CPU.

We present a fuzzy clustering approach for detecting flaws in the application of predefined medical protocols. In case of cardiac arrest, the outcome of the intervention is greatly influenced by the precise compliance to certain predefined procedures. We propose a clustering scheme in order to detect possible deviations from the standard protocols. Several interacting agents are employed in this regard. The fuzziness of our approach allows the discovery hybrid data which in this case may be an indication of the medical intervention quality level. We provide experiments on a dataset containing information from real patients that suffered cardiac arrest, on a synthetic dataset and on a standard dataset.

In the paper, we describe and develop more effective solutions of two important problems in bioinformatics. The first problem is the multiple sequence alignment problem and the second problem is RNA secondary structure prediction (folding) problem. Each of these problems should be solved with better results if we know the solution of the other one, but usually we only have sequences and we know neither the alignment nor the secondary structure. Precise algorithms solving both of these problems simultaneously are computationally pretentious according to the big length of RNA sequences. In this paper, we have described the method of speeding up the Sankoff’s simultaneous alignment and folding algorithm using the Carrillo-Lipman approach to cut off those computations, that can never lead to an optimal solution.

Reengineering is one of the key concepts in software maintenance and evolution. It generally includes some form of reverse engineering followed by some form of forward engineering or restructuring. In the paper we focus on database reverse engineering. Model-driven software engineering promotes the idea of abstracting implementation details by focusing on: models as first class entities and automated generation of models or code from other models. In the approach meta-models are used to define the modeling languages. A database reverse engineering process can benefit of integrating meta-modeling and meta-models in the process. The plethora of models related to databases points out to the need and importance of model-to-model transformations between these models at different abstraction levels. These transformations are based on meta-models that are conformed by the source and target models of the transformations. A database reverse engineering process can be performed through a chain of model-to-model transformations based on a set of meta-models. In the paper we discuss the importance of meta-modeling in the context of database reverse engineering and present a case study illustrating an approach to database reverse engineering.

We present evolutionary approach to program development based on absorption of genetic strings at different metalevels. Introducing the principles of software evolution as processes of semantical stability, expansion and contraction, we continue with an example illustrating how it is possible to integrate metalevel with base level and how this integrated computation works when driven by genetic string of codons, determining decisions for program construction and the result of constructed program execution. Next, we analyse the evolutionary circle at metalevel and we show that mentioned expansion and contraction is possible. The main contribution of the paper is that it breaks classic boundaries between models and programs because formal binding of metalevels and base level have been reached.

Since the beginning of teaching object-oriented programming at universities in the mid 90’s, university teachers are trying to come up with more effective ways of teaching. Number of researches has been made in this area. They are trying to identify errors teachers are making in learning process. These researches suggest different teaching methodologies and tools, which should help them to avoid these mistakes. The subject of this paper is to present a solution we developed to teach and illustrate basic concepts of object oriented paradigm through playing of computer game. In this approach, we are teaching basic principles, such as class, objects and relationship between them in the beginning of object oriented programming (OOP) course and postpone learning of specific objective language to later time. Also we are taking advantage of attractiveness of computer games to increase students motivation, which should lead to improved learning performance of students.

Algorithm visualization illustrates how algorithms work in a graphical way. It mainly aims to simplify and deepen the understanding of algorithms operation. Within the paper we discuss the possibility of enriching the standard methods of teaching algorithms, with the algorithm visualizations. As a step in this direction, we introduce the VizAlgo algorithm visualization platform, present our practical experiences and describe possible future directions, based on our experiences and exploration performed by means of a simple questionnaire.

This paper analyses basic concept of elastic cluster as a hybrid solution of high-performance computing tasks for computing grid and cloud. The analysis is focused on the context of managing resources and tasks in the elastic cluster. In this work design, model and implementation of scheduling algorithm is described. The scheduling algorithm is based on particle swarm optimization (PSO) and hill climbing (HC) optimization and it is appropriate combination of good features the both methods. The algorithm is implemented on HPC cluster into the resource manager Torque. There is included methodology of measurement and evaluation of the algorithm. The paper presents methods of verifying behaviour of algorithm for different tasks requirements, which are typical for grid or elastic cluster. We compare suitability of the proposed algorithm with known solutions. On the base of analysed results is confirmed that proposed algorithm better satisfies specific criteria of elastic cluster.