UGent Data Science Seminar: Prof. Krzysztof Dembczynski

UGent Data Science Seminar

Speaker: Prof. Krzysztof Dembczynski (Poznań University of Technology)
http://www.cs.put.poznan.pl/kdembczynski/

Title: Label tree algorithms for extreme classification

Abstract:
Extreme classification (XC) is a multi-class or multi-label problem with an extremely large output space consisting of even millions of labels. Examples of real-life problems of this scale can be found in image and document tagging, ranking and recommender systems, or web advertising. In this talk we will first discuss applications and challenges faced in XC. In the second part we will discuss a family of algorithms based on label trees, which includes hierarchical softmax (HSM) and probabilistic label trees (PLTs). The former is a well-known approach for reducing the time complexity of multi-class classification used, for example, in word2vec and fastText. The latter is a non-regret generalization of HSM to multi-label classification. The PLT model has been recently used in extremeText which extends fastText to deal with multi-label data and in Parabel, being currently one of the best XC algorithms.

Bio:
I am an assistant professor at Poznań University of Technology (Poland), in the laboratory of Intelligent Decision Support Systems headed by Prof. Roman Słowiński.
My research interests span the fields of machine learning and decision support. In particular, I was working on decision rule models, boosting and preference learning. Currently, my main research activity concerns multi-label classification and structured output prediction.

After the seminar, a sandwich lunch will be provided for registered participants.