Kaifu Zhang

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This work introduces a new approach to fake finger detection, based on the analysis of human skin elasticity. When a user puts a finger on the scanner surface, a sequence of fingerprint images which describes the finger deformation process is captured. Then two features which represent the skin elasticity are extracted from the image sequence: 1) the(More)
This paper proposes an algorithm to better solve the exploration-exploitation dilemma faced by model-less reinforcement learning agents. The main contribution is twofold: (1) The two facets of the exploration-exploitation dilemma are distinguished: in some cases, the agent faces a non-stationary environment, therefore it needs to choose the best moment to(More)
Acknowledgement: The generosity of 1000mercis Research Lab with data and managerial guidance has been invaluable. The assistance of Ilian Mihov on econometric issues is gratefully acknowledged. We thank Hubert Gatignon, Harald Hau, Andrew Stephen and seminar participants at INSEAD Brown Bag Seminar (2009) for their comments and suggestions. Finally, we(More)
This paper studies the strategic aspects of contextual advertising. Such advertising entails the display of relevant ads based on the topic of the content a consumer views and takes advantage of the possibility that consumers' content browsing preferences are indicative of their product preferences. The results show that contextual targeting impacts(More)
Learning to coordinate with non-stationary opponents is a major challenge for adaptive agents. Most previous research investigated only restricted classes of such dynamic opponents. The main contribution of this paper is twofold: (i) A class of generic non-stationary opponents is introduced. The opponents keep mixed strategies which change with less(More)
This paper studies the competition between Web 2.0 communities in a game theoretic framework. We model three important features of these institutions: (i) firms' content is usually user-generated; (ii) consumers' content preferences are governed by local network effects, and (iii) consumers have strong tendencies to multi-home. Our analyses reveal that(More)