Title: On Incentive-based Tagging

Abstract:

A social tagging system, such as delicious and Flickr, allows users to annotate resources (e.g., web pages and photos) with text descriptions called tags. Tags have proven to be invaluable information for searching, mining, and recommending resources. In practice, however, not all resources receive the same attention from users. As a result, while some highly- popular resources are over-tagged, most of the resources are under-tagged. Incomplete tagging on resources severely affects the effectiveness of all tag-based techniques and applications. We address an interesting question: if users are paid to tag specific resources, how can we allocate incentives to resources in a crowd-sourcing environment so as to maximize the tagging quality of resources? We address this question by observing that the tagging quality of a resource becomes stable after it has been tagged a sufficient number of times. We formalize the concepts of tagging quality (TQ) and tagging stability (TS) in measuring the quality of a resource’s tag description. We propose a theoretically optimal algorithm given a fixed “budget” (i.e., the amount of money paid for tagging resources). This solution decides the amount of rewards that should be invested on each resource in order to maximize tagging stability. We further propose a few simple, practical, and efficient incentive allocation strategies. On a dataset from delicious, our best strategy provides resources with a close-to-optimal gain in tagging stability.

Bio:

Reynold Cheng received the BEng degree in computer engineering and the MPhil in computer science and information systems from the University of Hong Kong (HKU) in 1998 and 2000, and the MSc and PhD degrees from the Department of Computer Science, Purdue University in 2003 and 2005. He is currently an associate professor in the Department of Computer Science at HKU.

Dr. Cheng was granted a HKU Outstanding Young Researcher Award 2011-12. He was the recipient of the 2010 Research Output Prize in the Department of Computer Science. From 2005 to 2008, he was an assistant professor in the Department of Computing at Hong Kong Polytechnic University, where he received two Performance Awards. He is a member of IEEE, ACM, ACM SIGMOD, and UPE. He has served on the program committees and review panels for leading database conferences and journals. He is a member of the editorial board of Information Systems and DAPD journal. His research interests include database management, as well as querying and mining of uncertain data.

时间：2013.6.27上午10:00

地点：高性能第一学术报告厅