[eas_cs_seminars] 21st March 2017

[Luca Rossi]

Dear all,

The next CS seminar will be on Tuesday 21/03 from 2pm to 3pm in MB220.
Dr. Leandro Minku (http://www.cs.le.ac.uk/people/llm11/) will be giving a
talk titled "Online Ensemble Learning of Data Streams with Gradually
Evolved Classes".

Abstract:
In machine learning, class evolution is the phenomenon of class emergence
and disappearance. It is likely to occur in many data stream problems,
which are problems where additional training data become available over
time. For example, in the problem of classifying tweets according to their
topic, new topics may emerge over time, and certain topics may become
unpopular and not discussed anymore. Therefore, class evolution is an
important research topic in the area of learning data streams. Existing
work implicitly regards class evolution as an abrupt change. However, in
many real world problems, classes emerge or disappear gradually. This gives
rise to extra challenges, such as non-stationary imbalance ratios between
the different classes in the problem. In this talk, I will present an
ensemble approach able to deal with gradually evolved classes. In order to
quickly adjust to class evolution, the ensemble maintains a base learner
for each class and dynamically creates, updates and (de)activates base
learners whenever new training data become available. It also uses a
dynamic undersampling technique in order to deal with the non-stationary
class imbalance present in this type of problem. Empirical studies
demonstrate the effectiveness of the proposed approach in various class
evolution scenarios in comparison with existing class evolution approaches.

See you all next week,
Luca
-- 
Luca Rossi

Lecturer in Computer Science
School of Engineering and Applied Science
Aston University
Web: http://www.cs.aston.ac.uk/~rossil/ <http://www.cs.bham.ac.uk/~rossil/>
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