On building ensembles of stacked denoising auto-encoding classifiers and their further improvement

To aggregate diverse learners and to train deep architectures are the two principal avenues towards increasing the expressive capabilities of neural networks. Therefore, their combinations merit attention. In this contribution, we study how to apply some conventional diversity methods-bagging and label switching- to a general deep machine, the stacked denoising auto-encoding classifier, in order to solve a number of appropriately selected image recognition problems. The main conclusion of our work is that binarizing multi-class problems is the key to obtain benefit from those diversity methods. Additionally, we check that adding other kinds of performance improvement procedures, such as pre-emphasizing training samples and elastic distortion mechanisms, further increases the quality of the results. In particular, an appropriate combination of all the above methods leads us to reach a new absolute record in classifying MNIST handwritten digits. These facts reveal that there are clear opportunities for designing more powerful classifiers by means of combining different improvement techniques. (C) 2017 Elsevier B.V. All rights reserved.This work has been partly supported by research grants CASI- CAM-CM ( S2013/ICE-2845, Madrid Community) and Macro-ADOBE (TEC2015-67719, MINECO-FEDER EU), as well as by the research network DAMA ( TIN2015-70308-REDT, MINECO )

Contributions on distance-based algorithms, multi-classifier construction and pairwise classification

179 p.Aurkezten den ikerketa lan honetan saikapen atazak landu dira, non helburua,sailkapen gainbegiratuaren artearen-egoera aberastea izan den. Sailkapengainbegiratuaren zenbait estrategi analizatu dira, beraien ezaugarri etaahuleziak aztertuz. Beraz, ezaugarri positiboak mantenduz, ahuleziak hobetzekosaiakera egin da. Hau burutu ahal izateko, sailkapen gainbegiratuarenzenbait estrategi konbinatzeaz gain, zenbait bilaketa heuristiko ere erabili dira.Sailkapen gainbegiratuko 3 ikerketa lerro desberdinetan burutu dira ekarpenak.Aurkezten diren lehenengo proposamenak, K-NN algoritmoan zentratzendira, honen zenbait bertsio aurkezten direlarik. Ondoren sailkatzaileen konbinaketarekinerlazionatutako beste lan bat aurkezten da. Eta azkenik, binakakosailkapenaren zenbait estrategi berritzaile proposatzen dira. Ekarpenhauek aldizkari edo konferentzi internazionaletan publikatuak edo bidaliakizan dira.Buruturiko experimentuetan, proposatutako algoritmoak artearen-estatuanaurkituriko zenbait algoritmorekin konparatu dira, emaitza interesgarriak lortuaz.Honetaz gain, emaitza hauetatik ondorio esanguratsuak eskuratzeko asmoz,test estatistikoen erabilera ere burutu da

Dynamic selection of the best base classifier in one versus one

Class binarization strategies decompose the original multi-class problem into several binary sub-problems. One versus One (OVO) is one of the most popular class binarization techniques, which considers every pair of classes as a different sub-problem. Usually, the same classifier is applied to every sub-problem and then all the outputs are combined by some voting scheme. In this paper we present a novel idea where for each test instance we try to assign the best classifier in each sub-problem of OVO. To do so, we have used two simple Dynamic Classifier Selection (DCS) strategies that have not been yet used in this context. The two DCS strategies use K-NN to obtain the local region of the test-instance, and the classifier that performs the best for those instances in the local region, is selected to classify the new test instance. The difference between the two DCS strategies remains in the weight of the instance. In this paper we have also proposed a novel approach in those DCS strategies. We propose to use the K-Nearest Neighbor Equality (K-NNE) method to obtain the local accuracy. K-NNE is an extension of K-NN in which all the classes are treated independently: the K nearest neighbors belonging to each class are selected. In this way all the classes take part in the final decision. We have carried out an empirical study over several UCI databases, which shows the robustness of our proposal.The work described in this paper was partially conducted within the Basque Government Research Team Grant IT313-10 and the University of the Basque Country UPV/EHU. I. Mendialdua holds a Grant from Basque Government

Bus line trajectories classification using weightless neural networks

Geo-enabled devices are ubiquitous nowadays. Within a diversity of possible applications using the huge of amount data generated by this technology, our work focuses on a chronic problem of Rio de Janeiro city: its public bus system. This text presents a framework for GPS trajectories classification, whose focus is the identification of bus routes of a public bus system. In order to do that, it was used the lightweight and versatile WiSARD, a weightless neural network classifier. Different binarization methods were used to adapt raw data to WiSARD’s binary input, making use of a set of rules defined by the application domain. Yet, it is evaluated a way of combining WiSARD through decision directed acyclic graphs. All these approachs result in different flavors of a neuro-symbolic learning system. The framework was tested against a vast data set created from open access and real-time data acquired from the current bus system of Rio de Janeiro city. Results obtained suggest the applicability of the proposed solution in a classification problem with more than 500 classes. Comparisons made also indicate an equivalent performance of WiSARD and other state-of-art and widely used machine learning methods. In addition, the framework described here is believed to be adaptable to other application domains.Dispositivos com localização espacial estão em toda parte hoje em dia. Dentre várias possíveis aplicações com a grande quantidade de dados gerada por esse tipo de equipamento, nosso trabalho foca em um problema crônico da cidade do Rio de Janeiro: seu sistema público de ônibus. Apresenta-se neste texto uma arquitetura para classificação de trajetórias GPS, cujo foco é a identificação de rotas de ônibus do sistema público. Para isso, utilizamos o leve e versátil classificador baseado em redes neurais sem peso WiSARD. Para a geração da entrada da rede, experimentamos diferentes formas de binarização, fazendo uso de regras definidas pelo problema. Ainda, avaliamos uma forma de combinação das redes WiSARD com o uso de um grafo acíclico de decisões. Todas essas propostas resultam em diferentes sabores de um sistema de aprendizado neurossimbólico. Tal arquitetura foi testada contra um vasto conjunto de dados construído a partir de dados fornecido em tempo real e de forma pública pelo sistema corrente da cidade do Rio de Janeiro. Os resultados obtidos indicam a aplicabilidade da solução proposta em um problema de classificação envolvendo mais de 500 classes. As comparações efetuadas indicam uma equiparação do modelo WiSARD com outros modelos em estado da arte. No mais, acreditamos que a metodologia aqui descrita possa ser utilizada com sucesso em outros domínios