Advanced Development of Social Search  
Yahoo! Inc  
701 First Avenue  
Sunnyvale, CA 94089 

Ph.D in Computer Sciences, UW-Madison  (Thesis advisors: Bart Miller and Tom Reps)

B.S. in Computer Sciences, Fudan University

Zhichen is technical lead of advanced development of social search at Yahoo! Inc. His current project is My Web 2.0 , a social search engine. Zhichen is the main and co-inventor of much of the main technologies underneath My Web2.0 such as the access-control policy, and collaborative tag suggestion algorithms.

Before joining Yahoo!, he was a research scientist at Hewlett-Packard Laboratories. He has initiated a number of projects include Pstore, a semantic-aware file store; Psearch, scalable distributed content indexing; and OASIS, overlay for adaptive and Scalable Internet Services. His is among the first to look into P2P information retrieval.

Zhichen holds a Ph.D. degree in Computer Sciences from UW-Madison. His dissertation proposes techniques to perform safety checking of machine code without the support from the high-level languages and compilers. These techniques can be used for checking the safety properties of web plug-ins, dynamically loaded OS modules, type-specific extensions to object relational databases, and Java native methods. He has also contributed to the parallel performance monitoring and debugging tools, Paradyn, where he proposed and implemented techniques that can dynamically instrument multi-threaded and distributed shared memory applications. He has extensive experience in integrated software development environments, and techniques to predict the performance of parallel programs.  Zhichen has co-authored over 30 papers in the areas of social tagging, computer networks, distributed systems, programming languages, program safety, peer-to-peer (P2P) computing, information retrieval. Many appear in top conferences such as PLDI, SIGCOMM, SIGIR, HotOS, HotNets. He has over 40 patent applications pending. Zhichen is a program co-chair of AEPP'05. Zhichen has served in program committees of ICDCS'[03,04,05,06], ISADS'05, IPTPS'04, INFOSCALE'06, ICPP'04, and NSF ITR panelist.

Selected Papers 

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Citations and  estimated impact of conferences and journals  according to Citeseer.

SIGIR'05 workshop

Yan Chen, Zhichen Xu, Chengxiang Zhai .  A scalable Semantic Indexing Framework for Peer-to-Peer Information Retrieval. SIGIR 2005 workshop: Heterogeneous and Distributed Information Retrieval, August 19th, 2005 - Salvador, Brazil 2004


Zhichen Xu, Puneet Sharma, Sung-Ju Lee, Sujata Banerjee .  Landmarks Reloaded: Scalable Network Proximity Estimation Using a Landmark Hierarchy. HPL Technical Report, 2003


Bo Shen, Zhichen Xu, Susie Wee, John Apostoloulos .  Semantic-Enhanced Distribution & Adaptation Networks, Invited paper, International Conference on Multimedia and Expo (ICME'04) , Taipei Taiwan, June 2004


Chunqiang Tang, Sandhya Dwarkdas, Zhichen Xu .  On Sclaing Latent Semantic Indexing for Large Peer-to-Peer Systems. 27th Annual International ACM SIGIR Conference , Sheffield, UK, July 2004


Zheng Zhang, Mallik Mahalingam, Zhichen Xu, Wenting Tang.  Scalable, Structured Data Placement over P2P Storage Utilities. 10th International Workshop on Future Trends in Distributed Computing Systems - FTDCS 2004, Suzhou, China, May 26-28, 2004

IEEE TPDS Li Xiao, Zhichen Xu, and Xiaodong Zhang, Low-Cost and Reliable Mutual Anonymity Protocols in Peer-to-Peer Networks. Special issue on Security Issues in Distributed Computing Systems of IEEE Transactions on Parallel and Distributed Systems, 2003.
SIGCOMM'03 Chunqiang Tang, Zhichen Xu, and Sandhya Dwarkadas, ``Peer-to-Peer Information Retrieval Using Self-Organizing Semantic Overlay Networks'',   ACM SIGCOMM 2003, Karlsruhe, Germany, August 2003. To appear.
WIAPP'03 Sujata Banerjee, Zhichen Xu, Sung-Ju Lee, and Chunqiang Tang.``Service Multicast for Media Distribution Networks'',  2003 IEEE Workshop on Internet Applications (WIAPP'03), San Jose, CA, June 2003.
NOSSDAV'03 Zhichen Xu, Chunqiang Tang, Sujata Banerjee, and Sung-Ju Lee.``Receiver Initiated Just-in-Time Tree Adaptation for Rich Media Distribution'',  The 13th International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV), Monterey, California, June 2003. Co-located with IWQoS.
HotOS-IX'03 Zhichen Xu, Magnus Karlsson, Chunqiang Tang, and Christos Karamanolis: "Towards a Semantic-Aware File Store". 9th Workshop on Hot Topics in Operating Systems (HotOS IX). May 18-21, 2003

Zhichen Xu, Mallik Mahalingam, and Magnus Karlsson: "Turining Heterogeneity into an Advantage in Overlay Routing". IEEE Infocom 2003. 

ICDCS'03 Zhichen Xu, Chunqiang Tang, and Zheng Zhang: "Building Topology-Aware Overlays using Global Soft-State". The 23rd International Conference on Distributed Computing Systems. May 19-22, 2003 Providence, Rhode Island USA
ICDCS'03 Li Xiao, Zhichen Xu and Xiaodong Zhang: "Efficient Mutual Anonymity Protocols for Peer-to-Peer Systems". The 23rd International Conference on Distributed Computing Systems. May 19-22, 2003 Providence, Rhode Island USA
FTDCS'2003 Chunqiang Tang and Zhichen Xu. ``pFilter: Global Information Filtering and Dissemination'',  the 9th International Workshop on Future Trends of Distributed Computing Systems, San Juan, Puerto Rico, May 2003. Expanded version available as HP Technical Report HPL-2002-304
FTDCS'2003 Mallik Mahalingam, Chunqiang Tang and Zhichen Xu. ``Towards a Semantic, Deep Archival File System''. The 9th International Workshop on Future Trends of Distributed Computing Systems, San Juan, Puerto Rico, May 2003. 
HotNets-I'02 Chunqiang Tang, Zhichen Xu, and Mallik Mahalingam: "pSearch: Information Retrieval in Structured Overlays". First Workshop on Hot Topics in Networks (HotNets-I). 28-29 October 2002. Princeton, New Jersey, USA.
P2P2002 Artur Andrzejak and Zhichen Xu:  "Scalable, Efficient Range Queries for Grid Information Services". The Second IEEE International Conference on Peer-to-Peer Computing (P2P2002), 5-7 September 2002, Linköping, Sweden.
NASA Mass Storage'02 M. Mahalingam, C. Karamanolis, M. Karlsson, Z. Xu. "Locating Logical Volumes in Large-Scale Networks".  Tenth NASA Goddard Conference on Mass Storage Systems and Technologies" that is held in cooperation with the Nineteenth IEEE Symposium on Mass Storage Systems at the Inn and Conference Center, University of Maryland University College, 3501 University Boulevard East, Adelphi, Maryland, USA, on April 15 - 18, 2002.
IPDPS'02 L. Xiao,  X. Zhang and Z. Xu. "On Reliable and Scalable Peer-to-Peer Web Document Sharing". Proceedings of 2002 International Parallel and Distributed Processing Symposium, (IPDPS'02).

Zhichen Xu, Thomas Reps, and Barton Miller, "Typestate Checking of Machine Code". 10th European Symposium on Programming. Genova, Italy, April 2001. Lecture Notes in Computer Science 2028, G. Goos, J. Hartmanis and J. van Leeuwen (Eds.) slides


Zhichen Xu, Barton Miller and Thomas Reps, "Safety Checking of Machine Code". SIGPLAN Conference on Programming Language Design and Implementation. Vancouver B.C., Canada. June 2000. slides.

PPoPP'99 Zhichen Xu, Barton Miller and Oscar Naim, "Dynamic Instrumentation of Threaded Applications". 7th SIGPLAN Symposium on Principles and Practice of Parallel Programming. Atlanta, Georgia. May 1999. slides

Zhichen Xu, James Larus and Barton Miller. "Shared-Memory Performance Profiling". 6th SIGPLAN Symposium on Principles and Practice of Parallel Programming. Las Vegas, Nevada. June 1997.


Jeffrey K. Hollingsworth, Barton P. Miller, Marcelo J. R. Goncalves, Oscar Naim, Zhichen Xu and Ling Zheng. "MDL: A Language and Compiler for Dynamic Program Instrumentation". 1997 International Conference on Parallel Architectures and Compilation Techniques. San Francisco, California. November 1997.


Zhichen Xu, "Simulation of heterogeneous networks of workstations". International Workshop on Modeling, Analysis and Simulation of Computer and Telecommunication Systems. San Jose, California. February 1996.

JPDC Zhichen Xu, Xiaodong Zhang and Ling Sun, "Semi-Empirical Performance Predictions". Journal of Parallel and Distributed Computing , 39, 1, 1996

Xiaodong Zhang, and Zhichen Xu, "Multiprocessor scalability prediction through detailed program execution analysis". 9th ACM International Conference on Supercomputing. Barcelona, Spain. July 1995. (best paper)

Sigmetrics'95 Xiaodong Zhang and Zhichen Xu, "A semi-empirical approach to scalability study". SIGMETRICS Conference on Measurement and Modeling of Computer Systems. 1995.

X. Zhang, Zhichen Xu and L. Sun, "Performance predictions on implicit communication systems". IEEE Symposium of Parallel and Distributed Processing. Dallas, Texas. October 1994.

Ph.D. Dissertation

Zhichen Xu, " Safety-Checking of Machine Code". Ph.D. Dissertation, University of Wisconsin, Madison, December 2000. slides, UC Davis talk

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