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Université de Fribourg

Toward link predictability of complex networks

Lü, Linyuan ; Pan, Liming ; Zhou, Tao ; Zhang, Yi-Cheng ; Stanley, H. Eugene

In: Proceedings of the National Academy of Sciences, 2015, vol. 112, no. 8, p. 2325–2330

The organization of real networks usually embodies both regularities and irregularities, and, in principle, the former can be modeled. The extent to which the formation of a network can be explained coincides with our ability to predict missing links. To understand network organization, we should be able to estimate link predictability. We assume that the regularity of a network is reflected in...

Université de Fribourg

Similarity from multi-dimensional scaling: solving the accuracy and diversity dilemma in information filtering

Zeng, Wei ; Zeng, An ; Liu, Hao ; Shang, Ming-Sheng ; Zhang, Yi-Cheng

In: PLoS ONE, 2014, vol. 9, no. 10, p. e111005

Recommender systems are designed to assist individual users to navigate through the rapidly growing amount of information. One of the most successful recommendation techniques is the collaborative filtering, which has been extensively investigated and has already found wide applications in e-commerce. One of challenges in this algorithm is how to accurately quantify the similarities of user pairs...

Université de Fribourg

Ranking reputation and quality in online rating systems

Liao, Hao ; Zeng, An ; Xiao, Rui ; Ren, Zhuo-Ming ; Chen, Duan-Bing ; Zhang, Yi-Cheng

In: PLoS ONE, 2014, vol. 9, no. 5, p. e97146

How to design an accurate and robust ranking algorithm is a fundamental problem with wide applications in many real systems. It is especially significant in online rating systems due to the existence of some spammers. In the literature, many well-performed iterative ranking methods have been proposed. These methods can effectively recognize the unreliable users and reduce their weight in judging...

Université de Fribourg

Optimizing online social networks for information propagation

Chen, Duan-Bing ; Wang, Guan-Nan ; Zeng, An ; Fu, Yan ; Zhang, Yi-Cheng

In: PLoS ONE, 2014, vol. 9, no. 5, p. e96614

Online users nowadays are facing serious information overload problem. In recent years, recommender systems have been widely studied to help people find relevant information. Adaptive social recommendation is one of these systems in which the connections in the online social networks are optimized for the information propagation so that users can receive interesting news or stories from their...

Université de Fribourg

Cultural evolution: the case of babies’ first names

Xi, Ning ; Zhang, Zi-Ke ; Zhang, Yi-Cheng ; Ge, Zehui ; She, Li ; Zhang, Kui

In: Physica A: Statistical Mechanics and its Applications, 2014, vol. 406, p. 139–144

In social sciences, there is currently rare consensus on the underlying mechanism for cultural evolution, partially due to lack of suitable data. The evolution of first names of newborn babies offers a remarkable example for such researches. In this paper, we employ the historical data on baby names from the United States to investigate the evolutionary process of culture, in particular focusing...

Université de Fribourg

Information filtering by similarity-preferential diffusion processes

Zeng, An ; Vidmer, Alexandre ; Medo, Matúš ; Zhang, Yi-Cheng

In: EPL (Europhysics Letters), 2014, vol. 105, no. 5, p. 58002

Recommender systems provide a promising way to address the information overload problem which is common in online systems. Based on past user preferences, a recommender system can find items that are likely to be relevant to a given user. Two classical physical processes, mass diffusion and heat conduction, have been used to design recommendation algorithms and a hybrid process based on them has...

Université de Fribourg

Firm competition in a probabilistic framework of consumer choice

Liao, Hao ; Xiao, Rui ; Chen, Duanbing ; Medo, Matúš ; Zhang, Yi-Cheng

In: Physica A: Statistical Mechanics and its Applications, 2014, vol. 400, p. 47–56

We develop a probabilistic consumer choice framework based on information asymmetry between consumers and firms. This framework makes it possible to study market competition of several firms by both quality and price of their products. We find Nash market equilibria and other optimal strategies in various situations ranging from competition of two identical firms to firms of different sizes and...

Université de Fribourg

Information filtering in sparse online systems: recommendation via semi-local diffusion

Zeng, Wei ; Zeng, An ; Shang, Ming-Sheng ; Zhang, Yi-Cheng

In: PLoS ONE, 2013, vol. 8, no. 11, p. e79354

With the rapid growth of the Internet and overwhelming amount of information and choices that people are confronted with, recommender systems have been developed to effectively support users’ decision-making process in the online systems. However, many recommendation algorithms suffer from the data sparsity problem, i.e. the user-object bipartite networks are so sparse that algorithms cannot...

Université de Fribourg

Membership in social networks and the application in information filtering

Zeng, Wei ; Zeng, An ; Shang, Ming-Sheng ; Zhang, Yi-Cheng

In: The European Physical Journal B, 2013, vol. 86, no. 9, p. 1–7

During the past few years, users’ membership in the online system (i.e. the social groups that online users joined) were widely investigated. Most of these works focus on the detection, formulation and growth of online communities. In this paper, we study users’ membership in a coupled system which contains user-group and user-object bipartite networks. By linking users’ membership...

Université de Fribourg

Impact of monetary policy changes on the Chinese monetary and stock markets

Tang, Yong ; Luo, Yong ; Xiong, Jie ; Zhao, Fei ; Zhang, Yi-Cheng

In: Physica A: Statistical Mechanics and its Applications, 2013, vol. 392, no. 19, p. 4435–4449

The impact of monetary policy changes on the monetary market and stock market in China is investigated in this study. The changes of two major monetary policies, the interest rate and required reserve ratio, are analyzed in a study period covering seven years on the interbank monetary market and Shanghai stock market. We find that the monetary market is related to the macro economy trend and we...