Title Semi-supervised learning for ordinal Kernel Discriminant Analysis
Authors PÉREZ ORTIZ, MARÍA, Gutierrez, P. A., CARBONERO RUZ, MARIANO, Hervas-Martinez, C., CARBONERO RUZ, MARIANO, PÉREZ ORTIZ, MARÍA
External publication No
Means Neural Netw.
Scope Article
Nature Científica
JCR Quartile 1
SJR Quartile 1
JCR Impact 5.28700
SJR Impact 1.33700
Area International
Web https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987984794&doi=10.1016%2fj.neunet.2016.08.004&partnerID=40&md5=1bea2dfc048c41f9a36b20baa7360ad4
Publication date 01/12/2016
ISI 000388548900006
Scopus Id 2-s2.0-84987984794
DOI 10.1016/j.neunet.2016.13$.004
Abstract Ordinal classification considers those classification problems where the labels of the variable to predict follow a given order. Naturally, labelled data is scarce or difficult to obtain in this type of problems because, in many cases, ordinal labels are given by a user or expert (e.g. in recommendation systems). Firstly, this paper develops a new strategy for ordinal classification where both labelled and unlabelled data are used in the model construction step (a scheme which is referred to as semi-supervised learning). More specifically, the ordinal version of kernel discriminant learning is extended for this setting considering the neighbourhood information of unlabelled data, which is proposed to be computed in the feature space induced by the kernel function. Secondly, a new method for semi-supervised kernel learning is devised in the context of ordinal classification, which is combined with our developed classification strategy to optimise the kernel parameters. The experiments conducted compare 6 different approaches for semi supervised learning in the context of ordinal classification in a battery of 30 datasets, showing (1) the good synergy of the ordinal version of discriminant analysis and the use of unlabelled data and (2) the advantage of computing distances in the feature space induced by the kernel function. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords Ordinal regression; Discriminant analysis; Semi-supervised learning; Classification; Kernel learning
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