Experiments with two Approaches for Tracking Drifting Concepts

This paper addresses the task of learning classifiers from streams of labelled data. In this case we can face the problem that the underlying concepts can change over time. The paper studies two mechanisms developed for dealing with changing concepts. Both are based on the time window idea. The first one forgets gradually, by assigning to the examples weight that gradually decreases over time. The second one uses a statistical test to detect changes in concept and then optimizes the size of the time window, aiming to maximise the classification accuracy on the new examples. Both methods are general in nature and can be used with any learning algorithm. The objectives of the conducted experiments were to compare the mechanisms and explore whether they can be combined to achieve a synergetic e ect. Results from experiments with three basic learning algorithms (kNN, ID3 and NBC) using four datasets are reported and discussed.

Leveraging Existing Plasma Simulation Codes

This paper describes the process of wrapping existing scientific codes in the domain of plasma physics simulations through the use of the Sun’s Java Native Interface. We have created a Java front-end for a particular functionality, offered by legacy native libraries, in order to achieve reusability and interoperability without having to rewrite these libraries. The technique, introduced in this paper, includes two approaches – the one-to-one mapping for wrapping a number of native functions, and using peer classes for wrapping native data structures.

Teaching Subroutines: As Early as Possible

Students on introductory courses in programming languages often experience difficulty understanding the basic principles of procedural programming. In this paper we discuss the importance of early understanding of the subroutine mechanism. Two approaches for self-training – static and dynamic - are presented and compared. The static approach is appropriate for written text in paper textbook. The dynamic approach is suitable for interactive training using a computer. An interactive module was developed for teaching subroutines.

Върху два подхода за преподаване на понятията в курса по компютърна топология

Kalin Georgiev, Dimitrina Stavrova - We consider two approaches for introducing topological notions in a course of Computational Topology. One is an intuitive inductive introduction of a notion; the other is theoretical-analytical one. As an example we treat the notions of interior, closure and boundary of a set in a topological space. We analyze several visual representations as well as analytical ones. Examples of tests and quiz problems are considered. Comparisons of student’s achievement on different type of problems are presented.