Scielo RSS <![CDATA[Journal of the Brazilian Computer Society]]> http://www.scielo.br/rss.php?pid=0104-650020080004&lang=en vol. 14 num. 4 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[<b>Letter From The Editor-In-Chief</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-65002008000400001&lng=en&nrm=iso&tlng=en <![CDATA[<b>A hybrid heuristic for the multi-plant capacitated lot sizing problem with setup carry-over</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-65002008000400002&lng=en&nrm=iso&tlng=en This paper addresses the capacitated lot sizing problem (CLSP) with a single stage composed of multiple plants, items and periods with setup carry-over among the periods. The CLSP is well studied and many heuristics have been proposed to solve it. Nevertheless, few researches explored the multi-plant capacitated lot sizing problem (MPCLSP), which means that few solution methods were proposed to solve it. Furthermore, to our knowledge, no study of the MPCLSP with setup carry-over was found in the literature. This paper presents a mathematical model and a GRASP (Greedy Randomized Adaptive Search Procedure) with path relinking to the MPCLSP with setup carry-over. This solution method is an extension and adaptation of a previously adopted methodology without the setup carry-over. Computational tests showed that the improvement of the setup carry-over is significant in terms of the solution value with a low increase in computational time. <![CDATA[<b>Portuguese corpus-based learning using ETL</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-65002008000400003&lng=en&nrm=iso&tlng=en We present Entropy Guided Transformation Learning models for three Portuguese Language Processing tasks: Part-of-Speech Tagging, Noun Phrase Chunking and Named Entity Recognition. For Part-of-Speech Tagging, we separately use the Mac-Morpho Corpus and the Tycho Brahe Corpus. For Noun Phrase Chunking, we use the SNR-CLIC Corpus. For Named Entity Recognition, we separately use three corpora: HAREM, MiniHAREM and LearnNEC06. For each one of the tasks, the ETL modeling phase is quick and simple. ETL only requires the training set and no handcrafted templates. ETL also simplifies the incorporation of new input features, such as capitalization information, which are sucessfully used in the ETL based systems. Using the ETL approach, we obtain state-of-the-art competitive performance in all six corpora-based tasks. These results indicate that ETL is a suitable approach for the construction of Portuguese corpus-based systems. <![CDATA[<b>Fast two-step segmentation of natural color scenes using hierarchical region-growing and a color-gradient network</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-65002008000400004&lng=en&nrm=iso&tlng=en We present evaluation results with focus on combined image and efficiency performance of the Gradient Network Method to segment color images, especially images showing outdoor scenes. A brief review of the techniques, Gradient Network Method and Color Structure Code, is also presented. Different region-growing segmentation results are compared against ground truth images using segmentation evaluation indices Rand and Bipartite Graph Matching. These results are also confronted with other well established segmentation methods (EDISON and JSEG). Our preliminary results show reasonable performance in comparison to several state-of-art segmentation techniques, while also showing very promising results comparatively in the terms of efficiency, indicating the applicability of our solution to real time problems. <![CDATA[<b>A privacy service for location-based collaboration among mobile users</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-65002008000400005&lng=en&nrm=iso&tlng=en The potential loss of privacy due to the use of location-based applications may be one of the greatest obstacles to their wider acceptance. Nevertheless, most research about privacy management to-date has not taken into consideration the complexity in the utilization of collaborative applications that may require users' location sharing among participants. In this article, we propose a privacy service that helps users to maintain their privacy policy in a flexible and incremental way. We also carried out a qualitative evaluation study whose results illustrate several challenges that should be handled in the design of such a service.