445 research outputs found
Directed Feedback Vertex Set is Fixed-Parameter Tractable
We resolve positively a long standing open question regarding the
fixed-parameter tractability of the parameterized Directed Feedback Vertex Set
problem. In particular, we propose an algorithm which solves this problem in
.Comment: 14 page
The ICON Challenge on Algorithm Selection
Algorithm selection is of increasing practical relevance in a variety of applications. Many approaches have been proposed in the literature, but their evaluations are often not comparable, making it hard to judge which approaches work best. The ICON Challenge on Algorithm Selection objectively evaluated many prominent approaches from the literature, making them directly comparable for the first time. The results show that there is still room for improvement, even for the very best approaches
Revisiting two-sided stability constraints
We show that previous filtering propositions on two-sided stability problems do not enforce arc consistency (AC), however they maintain Bound(D) Consistency (BC(D)). We propose an optimal algorithm achieving BC(D) with O(L) time complexity where L is the length of the preference lists. We also show an adaptation of this filtering approach to achieve AC. Next, we report the first polynomial time algorithm for solving the hospital/resident problem with forced and forbidden pairs. Furthermore, we show that the particular case of this problem for stable marriage can be solved in O(n2) which improves the previously best complexity by a factor of n2. Finally, we present a comprehensive set of experiments to evaluate the filtering propositions
Language learning gains among users of English Liulishuo
This study investigated improvements in English language ability (as measured by the British Council
Aptis test) among 746 users of the English Liulishuo app, the flagship mobile app produced by LAIX
Inc. (NYSE:LAIX), taking courses at three levels over a period of approximately two months
Improving the quality of the personalized electronic program guide
As Digital TV subscribers are offered more and more channels, it is becoming increasingly difficult for them to locate the right programme information at the right time. The personalized Electronic Programme Guide (pEPG) is one solution to this problem; it leverages artificial intelligence and user profiling techniques to learn about the viewing preferences of individual users in order to compile personalized viewing guides that fit their individual preferences. Very often the limited availability of profiling information is a key limiting factor in such personalized recommender systems. For example, it is well known that collaborative filtering approaches suffer significantly from the sparsity problem, which exists because the expected item-overlap between profiles is usually very low. In this article we address the sparsity problem in the Digital TV domain. We propose the use of data mining techniques as a way of supplementing meagre ratings-based profile knowledge with additional item-similarity knowledge that can be automatically discovered by mining user profiles. We argue that this new similarity knowledge can significantly enhance the performance of a recommender system in even the sparsest of profile spaces. Moreover, we provide an extensive evaluation of our approach using two large-scale, state-of-the-art online systems—PTVPlus, a personalized TV listings portal and Físchlár, an online digital video library system
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