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Publications

Publications by Alípio Jorge

2006

Improving SVM-linear predictions using CART for example selection

Authors
Moreira, JM; Jorge, AM; Soares, C; de Sousa, JF;

Publication
FOUNDATIONS OF INTELLIGENT SYSTEMS, PROCEEDINGS

Abstract
This paper describes the study on example selection in regression problems using mu-SVM (Support Vector Machine) linear as prediction algorithm. The motivation case is a study done on real data for a problem of bus trip time prediction. In this study we use three different training sets: all the examples, examples from past days similar to the day where prediction is needed, and examples selected by a CART regression tree. Then, we verify if the CART based example selection approach is appropriate on different regression data sets. The experimental results obtained are promising.

2006

Distribution rules with numeric attributes of interest

Authors
Jorge, AM; Azevedo, PJ; Pereira, F;

Publication
KNOWLEDGE DISCOVERY IN DATABASES: PKDD 2006, PROCEEDINGS

Abstract
In this paper we introduce distribution rules, a kind of association rules with a distribution on the consequent. Distribution rules are related to quantitative association rules but can be seen as a more fundamental concept, useful for learning distributions. We formalize the main concepts and indicate applications to tasks such as frequent pattern discovery, sub group discovery and forecasting. An efficient algorithm for the generation of distribution rules is described. We also provide interest measures, visualization techniques and evaluation.

2012

Hierarchical confidence-based active clustering

Authors
Nogueira, BM; Jorge, AM; Rezende, SO;

Publication
Proceedings of the ACM Symposium on Applied Computing

Abstract
In this paper, we address the problem of semi-supervised hierarchical clustering by using an active clustering solution with cluster-level constraints. This active learning approach is based on a concept of merge confidence in agglomerative clustering. The proposed method was compared with an un-supervised algorithm (average-link) and a semi-supervised algorithm based on pairwise constraints. The results show that our algorithm tends to be better than the pairwise constrained algorithm and can achieve a significant improvement when compared to the unsupervised algorithm. © 2012 Authors.

2008

Incremental collaborative filtering for binary ratings

Authors
Miranda, C; Jorge, AM;

Publication
Proceedings - 2008 IEEE/WIC/ACM International Conference on Web Intelligence, WI 2008

Abstract
The use of collaborative filtering (CF) recommenders on the Web is typically done in environments where data is constantly flowing. In this paper we propose an incremental version of item-based CF for implicit binary ratings, and compare it with a non-incremental one, as well as with an incremental user-based approach. We also study the usage of sparse matrices in these algorithms. We observe that recall and precision tend to improve when we continuously add information to the recommender model, and that the time spent for recommendation does not degrade. Time for updating the similarity matrix is relatively low and motivates the use of the item-based incremental approach. © 2008 IEEE.

2008

The impact of contextual information on the accuracy of existing recommender systems for Web personalization

Authors
Domingues, MA; Jorge, AM; Soares, C;

Publication
Proceedings - 2008 IEEE/WIC/ACM International Conference on Web Intelligence, WI 2008

Abstract
Traditionally, recommender systems for the Web deal with applications that have two types of entities/dimensions, users and items. With these dimensions, a recommendation model can be built and used to identify a set of N items that will be of interest to a certain user. In this paper we propose a direct method that enriches the information in the access logs with new dimensions. We empirically test this method with two recommender systems, an item-based collaborative filtering technique and association rules, on three data sets. Our results show that while collaborative filtering is not able to take advantage of the new dimensions added, association rules are capable of profiting from our direct method. © 2008 IEEE.

2006

Factor analysis to support the visualization and interpretation of clusters of portal users

Authors
Rebelo, C; Brito, PQ; Soares, C; Jorge, A;

Publication
2006 IEEE/WIC/ACM International Conference on Web Intelligence, (WI 2006 Main Conference Proceedings)

Abstract
Clusterings based on many variables are difficult to visualize and interpret. We present a methodology based on Factor Analysis (FA) which can be used for that purpose. FA generates a small set of variables which encode most of the information in the original variables. We apply the methodology to segment the users of a web portal, using access log data. It not only makes it simpler to visualize and understand the clusters which are obtained on the original variables but it also helps the analyst in selecting some of the original variables for further analysis of those clusters.

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