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Université de Fribourg

Link prediction in weighted networks: The role of weak ties

Lü, Linyuan ; Zhou, Tao

In: EPL Europhysics Letters, 2010, vol. 89, no. 1, p. 18001

Plenty of algorithms for link prediction have been proposed and were applied to various real networks. Among these algorithms, the weights of links are rarely taken into account. In this letter, we use local similarity indices to estimate the likelihood of the existence of links in weighted networks, including Common Neighbor, Adamic-Adar Index, Resource Allocation Index, and their weighted...

Université de Fribourg

Relevance is more significant than correlation: Information filtering on sparse data

Shang, Ming-Sheng ; Lü, Linyuan ; Zeng, Wei ; Zhang, Yi-Cheng ; Zhou, Tao

In: Europhysics Letters, 2009, vol. 88, no. 6, p. 68008

In some recommender systems where users can vote objects by ratings, the similarity between users can be quantified by a benchmark index, namely the Pearson correlation coefficient, which reflects the rating correlations. Another alternative way is to calculate the similarity based solely on the relevance information, namely whether a user has voted an object. The former one uses more information...

Université de Fribourg

Effects of user's tastes on personalized recommendation

Liu, Jian-Guo ; Zhou, Tao ; Wang, Bing-Hong ; Zhang, Yi-Cheng ; Guo, Qiang

In: International Journal of Modern Physics C, 2009, vol. 20, no. 12, p. 1925-1932

In this paper, based on a weighted projection of the user-object bipartite network, we study the effects of user tastes on the mass-diffusion-based personalized recommendation algorithm, where a user's tastes or interests are defined by the average degree of the objects he has collected. We argue that the initial recommendation power located on the objects should be determined by both of their...

Université de Fribourg

Effects of high-order correlations on personalized recommendations for bipartite networks

Liu, Jian-Guo ; Zhou, Tao ; Che, Hong-An ; Wang, Bing-Hong ; Zhang, Yi-Cheng

In: Physica A, 2010, vol. 389, no. 4, p. 881-886

In this paper, we introduce a modified collaborative filtering (MCF) algorithm, which has remarkably higher accuracy than the standard collaborative filtering. In the MCF, instead of the cosine similarity index, the user–user correlations are obtained by a diffusion process. Furthermore, by considering the second-order correlations, we design an effective algorithm that depresses the influence...

Université de Fribourg

Adaptive model for recommendation of news

Medo, Matúš ; Zhang, Yi-Cheng ; Zhou, Tao

In: Europhysics Letters, 2009, vol. 88, no. 3, p. 38005

Most news recommender systems try to identify users' interests and news' attributes and use them to obtain recommendations. Here we propose an adaptive model which combines similarities in users' rating patterns with epidemic-like spreading of news on an evolving network. We study the model by computer agent-based simulations, measure its performance and discuss its robustness against bias and...

Université de Fribourg

Accurate and diverse recommendations via eliminating redundant correlations

Zhou, Tao ; Su, Ri-Qi ; Liu, Run-Ran ; Jiang, Luo-Luo ; Wang, Bing-Hong ; Zhang, Yi-Cheng

In: New Journal of Physics, 2009, vol. 11, p. 123008

In this paper, based on a weighted projection of a bipartite user-object network, we introduce a personalized recommendation algorithm, called network-based inference (NBI), which has higher accuracy than the classical algorithm, namely collaborative filtering. In NBI, the correlation resulting from a specific attribute may be repeatedly counted in the cumulative recommendations from different...

Université de Fribourg

Collaborative filtering based on multi-channel diffusion

Shang, Ming-Sheng ; Jin, Ci-Hang ; Zhou, Tao ; Zhang, Yi-Cheng

In: Physica A: Statistical Mechanics and its Applications, 2009, vol. 388, no. 23, p. 4867-4871

In this paper, by applying a diffusion process, we propose a new index to quantify the similarity between two users in a user–object bipartite graph. To deal with the discrete ratings on objects, we use a multi-channel representation where each object is mapped to several channels with the number of channels being equal to the number of different ratings. Each channel represents a certain...

Université de Fribourg

Scaling and memory in recurrence intervals of Internet traffic

Cai, Shi-Min ; Fu, Zhong-Qian ; Zhou, Tao ; Gu, Jun ; Zhou, Pei-Ling

In: Europhysics Letters, 2009, vol. 87, p. 68001

By studying the statistics of recurrence intervals, τ, between volatilities of Internet traffic rate changes exceeding a certain threshold q, we find that the probability distribution functions, Pq(τ), for both byte and packet flows, show scaling property as $P_{q}(\tau)=\frac{1}{\overline{\tau}}f(\frac{\tau}{\overline{\tau}})$. The scaling functions for both byte and packet flows obey the...

Université de Fribourg

Similarity index based on local paths for link prediction of complex networks

Lü, Linyuan ; Jin, Ci-Hang ; Zhou, Tao

In: Physical Review E, 2009, vol. 80, no. 4, p. 046122

Predictions of missing links of incomplete networks, such as protein-protein interaction networks or very likely but not yet existent links in evolutionary networks like friendship networks in web society, can be considered as a guideline for further experiments or valuable information for web users. In this paper, we present a local path index to estimate the likelihood of the existence of a...

Université de Fribourg

Reducing the heterogeneity of payoffs: an effective way to promote cooperation in the prisoner's dilemma game

Jiang, Luo-Luo ; Zhao, Ming ; Yang, Han-Xin ; Wakeling, Joseph Rushton ; Wang, Bing-Hong ; Zhou, Tao

In: Physical Review E, 2009, vol. 80, p. 031144

In this paper, the accumulated payoff of each agent is regulated so as to reduce the heterogeneity of the distribution of all such payoffs. It is found that there exists an optimal regulation strength at which cooperation in the prisoner's dilemma game is optimally promoted. If the heterogeneity is regulated to be either too weak or too strong, the promotive effect disappears and the evolution of...