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Consortium of Swiss Academic Libraries

Tag-Aware Recommender Systems: A State-of-the-Art Survey

Zhang, Zi-Ke ; Zhou, Tao ; Zhang, Yi-Cheng

In: Journal of Computer Science and Technology, 2011, vol. 26, no. 5, p. 767-777

Consortium of Swiss Academic Libraries

Empirical analysis on a keyword-based semantic system

Zhang, Zi-Ke ; Lü, Linyuan ; Liu, Jian-Guo ; Zhou, Tao

In: The European Physical Journal B, 2008, vol. 66, no. 4, p. 557-561

Université de Fribourg

Positive periodic solutions of an epidemic model with seasonality

Sun, Gui-Quan ; Bai, Zhenguo ; Zhang, Zi-Ke ; Zhou, Tao ; Jin, Zhen

In: The Scientific World Journal, 2013, vol. 2013, p. -

An SEI autonomous model with logistic growth rate and its corresponding nonautonomous model are investigated. For the autonomous case, we give the attractive regions of equilibria and perform some numerical simulations. Basic demographic reproduction Rd number is obtained. Moreover, only the basic reproduction number R0 cannot ensure the existence of the positive equilibrium, which needs...

Université de Fribourg

Deviation of Zipf’s and Heaps’ laws in human languages with limited dictionary sizes

Lü, Linyuan ; Zhang, Zi-Ke ; Zhou, Tao

In: Scientific Reports, 2013, vol. 3, p. -

Zipf's law on word frequency and Heaps' law on the growth of distinct words are observed in Indo-European language family, but it does not hold for languages like Chinese, Japanese and Korean. These languages consist of characters, and are of very limited dictionary sizes. Extensive experiments show that: (i) The character frequency distribution follows a power law with exponent close to one, at...

Université de Fribourg

Recommender systems

Lü, Linyuan ; Medo, Matúš ; Yeung, Chi Ho ; Zhang, Yi-Cheng ; Zhang, Zi-Ke ; Zhou, Tao

In: Physics Reports, 2012, vol. 519, no. 1, p. 1–49

The ongoing rapid expansion of the Internet greatly increases the necessity of effective recommender systems for filtering the abundant information. Extensive research for recommender systems is conducted by a broad range of communities including social and computer scientists, physicists, and interdisciplinary researchers. Despite substantial theoretical and practical achievements, unification...

Université de Fribourg

How altruism works: An evolutionary model of supply networks

Ge, Zehui ; Zhang, Zi-Ke ; Lü, Linyuan ; Zhou, Tao ; Xi, Ning

In: Physica A: Statistical Mechanics and its Applications, 2012, vol. 391, no. 3, p. 647–655

Recently, supply networks have attracted increasing attention from the scientific community. However, it lacks serious consideration of social preference in Supply Chain Management. In this paper, we develop an evolutionary decision-making model to characterize the effects of suppliers’ altruism in supply networks, and find that the performances of both suppliers and supply chains are improved...

Université de Fribourg

Tag-aware recommender systems : a state-of-the-art survey

Zhang, Zi-Ke ; Zhou, Tao ; Zhang, Yi-Cheng

In: Journal of Computer Science and Technology, 2011, vol. 26, no. 5, p. 767-777

In the past decade, Social Tagging Systems have attracted increasing attention from both physical and computer science communities. Besides the underlying structure and dynamics of tagging systems, many efforts have been addressed to unify tagging information to reveal user behaviors and preferences, extract the latent semantic relations among items, make recommendations, and so on....

Université de Fribourg

An item-oriented recommendation algorithm on cold-start problem

Qiu, Tian ; Chen, Guang ; Zhang, Zi-Ke ; Zhou, Tao

In: EPL - Europhysics Letters, 2011, vol. 95, no. 5, p. 58003

Based on a hybrid algorithm incorporating the heat conduction and probability spreading processes (Proc. Natl. Acad. Sci. U.S.A., 107 (2010) 4511), in this letter, we propose an improved method by introducing an item-oriented function, focusing on solving the dilemma of the recommendation accuracy between the cold and popular items. Differently from previous works, the present algorithm does not...

Université de Fribourg

Emergence of scale-free leadership structure in social recommender systems

Zhou, Tao ; Medo, Matúš ; Cimini, Giulio ; Zhang, Zi-Ke ; Zhang, Yi-Cheng

In: PLoS ONE, 2011, vol. 6, no. 7, p. e20648

The study of the organization of social networks is important for the understanding of opinion formation, rumor spreading, and the emergence of trends and fashion. This paper reports empirical analysis of networks extracted from four leading sites with social functionality (Delicious, Flickr, Twitter and YouTube) and shows that they all display a scale-free leadership structure. To reproduce this...

Université de Fribourg

Personalized recommendation via integrated diffusion on user–item–tag tripartite graphs

Zhang, Zi-Ke ; Zhou, Tao ; Zhang, Yi-Cheng

In: Physica A: Statistical Mechanics and its Applications, 2010, vol. 389, no. 1, p. 179-186

Personalized recommender systems are confronting great challenges of accuracy, diversification and novelty, especially when the data set is sparse and lacks accessorial information, such as user profiles, item attributes and explicit ratings. Collaborative tags contain rich information about personalized preferences and item contents, and are therefore potential to help in providing better...