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                                                     Seminar

             Department of Systems Engineering and Engineering Management
                                  The Chinese University of Hong Kong

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Title

:

Managing Attribute Uncertainty in a Database System

　

　

　

Speaker

:

Prof. Reynold Cheng

　

　

Department of Computing

　

　

The Hong Kong Polytechnic University

　

　

　

Date

:

November 19th, 2007 (Monday)

　

　

　

Time

:

4:30 p.m. - 5:30 p.m.

　

　

　

Venue

:

Room 513

　

　

William M.W. Mong Engineering Building

　

　

(Engineering Building Complex Phase 2)

　

　

CUHK

　

　

　

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Abstract:
　

In systems that monitor continuously-changing entities like locations of moving objects and temperature values, data are obtained from sensors and streamed continuously to the database. Due to limited bandwidth and battery power, it is infeasible for the system to keep track of the actual values of the entities. A user may also desire to protect his/her privacy by providing a less precise location. Services and queries that base their decisions on these queries can produce incorrect answers. In this talk, we discuss how uncertainty in attribute values can be modeled and queried in a database system. We discuss the concept of probabilistic queries, where query answers are augmented with statistical confidence. We also present a database prototype, called ORION, that treats data uncertainty in a database as a "first-class citizen".


In the second part of the talk, we focus on an uncertainty management problem commonly found in location-based services. We consider a location-based query, where a user's current position is taken into account when the query is issued. An example is "find the available cabs within two miles of my current location". The accuracy and complexity of this kind of query is affected by the inexactness of locations of both the query user and the location database. We present several methods that take into account of these two factors, and illustrate how answer probabilities can be computed with high computational and I/O performance.


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Biography:
　

Dr. Reynold Cheng received his BEng (Computer Engineering) in 1998, and MPhil (Computer Science and Information Systems) in 2000, from the Department of Computer Science in the University of Hong Kong. He then obtained his MSc and PhD from the Department of Computer Science of Purdue University in 2003 and 2005 respectively.

Dr. Cheng is currently an assistant professor in the Department of Computing of the Hong Kong Polytechnic University. He received the Performance Reward in 2006 from HKPU. He was a visiting scientist in the Institute of Parallel and Distributed Systems in the University of Stuttgart in 2006 and 2007. He is a member of the IEEE, the ACM, and the ACM Special Interest Group on Management of Data (SIGMOD). He has served as PC member and reviewer for international conferences and journals including TKDE, TMC, IS, VLDBJ, VLDB, ICDE and ICDM. His personal homepage can be found in http://www.comp.polyu.edu.hk/~csckcheng/.


************************* ALL ARE WELCOME ************************

　

　

　

Host

:

Prof. Jeffrey Xu Yu

Tel

:

(852) 2609-8309

Email

:

yu@se.cuhk.edu.hk    

　

　

　

Enquiries

:

Prof. Nan Chen or Prof. Sean X. Zhou

　

:

Department of Systems Engineering and Engineering Management

　

　

CUHK

Website

:

http://www.se.cuhk.edu.hk/~seg5810

Email

:

seg5810@se.cuhk.edu.hk

　

　

　

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