Learning vector quantization for (dis-)similarities

Prototype-based methods often display very intuitive classification and learning rules. However, popular prototype based classifiers such as learning vector quantization (LVQ) are restricted to vectorial data only. In this contribution, we discuss techniques how to extend LVQ algorithms to more general data characterized by pairwise similarities or dissimilarities only. We propose a general framework how the methods can be combined based on the background of a pseudo-Euclidean embedding of the data. This covers the existing approaches kernel generalized relevance LVQ and relational generalized relevance LVQ, and it opens the way towards two novel approach, kernel robust soft LVQ and relational robust soft LVQ. Interestingly, also unsupervised prototype based techniques which are based on a cost function can be put into this framework including kernel and relational neural gas and kernel and relational self-organizing maps (based on Heskes' cost function). We demonstrate the performance of the LVQ techniques for similarity or dissimilarity data in several benchmarks, reaching state of the art results.