Ibai Gurrutxaga

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The validation of the results obtained by clustering algorithms is a fundamental part of the clustering process. The most used approaches for cluster validation are based on internal cluster validity indices. Although many indices have been proposed, there is no recent extensive comparative study of their performance. In this paper we show the results of an(More)
Matrix transposition is a basic operation for several computing tasks. Hence, transposing a matrix in a computer’s main memory has been well studied since many years ago. More recently, the out-of-place matrix transposition has been performed efficiently in graphical processing units (GPU), which are broadly used today for general purpose computing.(More)
Malware detection is an important problem today. New malware appears every day and in order to be able to detect it, it is important to recognize families of existing malware. Data mining techniques will be very helpful in this context; concretely unsupervised learning methods will be adequate. This work presents a comparison of the behaviour of two(More)
When different subsamples of the same data set are used to induce classification trees, the structure of the built classifiers is very different. The stability of the structure of the tree is of capital importance in many domains, such as illness diagnosis, fraud detection in different fields, customer’s behaviour analysis (marketing), etc, where(More)
The popularity of computer networks broadens the scope for network attackers and increases the damage these attacks can cause. In this context, any complete security package includes a network Intrusion Detection System (nIDS). This work focuses on nIDSs which work by scanning the network traffic. We present a service-independent payload processing(More)
Class imbalance problems have lately become an important area of study in machine learning and are often solved using intelligent resampling methods to balance the class distribution. The aim of this work is to show that balancing the class distribution is not always the best solution when intelligent resampling methods are used, i.e. there is often a class(More)
Passenger's transportation in urban areas is an increasing problem in the current society. The expansion of the current roads is not an adequate solution to this problem but the passenger's transportation has to be planned in order to mitigate the negative effects that originates: traffic congestion, accidents, pollution, etc.
The evaluation and comparison of internal cluster validity indices is a critical problem in the clustering area. The methodology used in most of the evaluations assumes that the clustering algorithms work correctly. We propose an alternative methodology that does not make this often false assumption. We compared 7 internal cluster validity indices with both(More)