• E. Pitoura and G. Samaras. Data Management for Mobile Computing, Kluwer Academic Publishers, 1998.

• S. Banerjee, P. K. Chrysanthis, and E. Pitoura. Proceedings of the ACM International Workshop on Data Engineering for Wireless and Mobile Access, May 20, 2001, Santa Barbara, California, held in conjunction with SIGMOD/PODS 2001, ACM Press.

• S. Banerjee, P. K. Chrysanthis, and E. Pitoura. Proceedings of the ACM International Workshop on Data Engineering for Wireless and Mobile Access, August 20, 1999, Seattle, held in conjunction with MobiCom '99.

• G. Koloniari and E. Pitoura. A Recall-Based Cluster Formation Game in Peer-to-Peer Systems (Extended Version), University of Ioannina, Computer Science Departmnet, Technical Report No 2009-03 VLDB 2009

• M. Drosou, K. Stefanidis and E. Pitoura, Preference-Aware Publish/Subscribe Delivery with Diversity, DEBS 2009

• G. Koloniari and E. Pitoura. Distributed Structural Relaxation of XPath Queries. ICDE 2009.

• K. Lillis and E. Pitoura. Cooperative XPATH Caching, SIGMOD 2008

• K. Stefanidis and E. Pitoura. Fast Contextual Scoring of Database Tuples EDBT 2008

• G. Koloniari and E. Pitoura. A Clustered Index Approach to Distributed XPath Processing ICDE 2008 (poster paper) .

• G. Koloniari and E. Pitoura. Recall-Based Cluster Reformulation by Selfish Peers, NetDB 2008.

• K. Fotiadou and E. Pitoura. BITPEER: Continuous Subspace Skyline Computation with Distributed Bitmap Indexes, DAMAP 2008

• N. Folinas, P. Vassiliadis, E. Pitoura, E. Papapetrou, A. Zarras. Context-Aware Query Processing in Ad-Hoc Environments of Peers. Journal of Electronic Commerce in Organizations (JECO), vol. 6, no. 1, pp. 38-62, IGI Global.

• D. Athanasopoulos, A.V. Zarras, V. Issarny, E. Pitoura, P. Vassiliadis. CoWSAMI: Interface-aware Context Gathering in Ambient Intelligence Environments. Pervasive and Mobile Computing (PMCJ), vol. 4, no. 3, pp. 360-389, Elsevier.

2007

• K. Stefanidis, E. Pitoura and P. Vassiliadis. Adding Context to Preferences ICDE 2007

• K. Stamkopoulos, E. Pitoura and P. Vassiliadis. Efficient Deployment of Web Servide Workflows. 2nd International Workshop on Services Engineering (SEIW 2007) in conjunction with ICDE 2007.

• K. Stefanidis and E. Pitoura. Approximate Contextual Preference Scoring in Digital Libraries. In Proc. of the tenth DELOS Thematic Workshop on Personalized Access, Profile Management and Context Awareness in Digital Libraries (PersDL 2007), in conjuction with UM 2007 Conference, June 29-30, 2007, Corfu, Greece.

• K. Stefanidis, E. Pitoura and P. Vassiliadis. On Relaxing Contextual Preference Queries. In Proc. of the 2nd International Workshop on Managing Context Information and Semantics in Mobile Environments (MCISME 2007), in conjunction with MDM 2007, May 7, 2007, Mannheim, Germany.

• E. Pitoura and P. K. Chrysanthis, Caching and Replication in Mobile Data Management, In Data Engineering Bulletin, September 2007

• P. Skyvalidas, E. Pitoura and V. V. Dimakopoulos, Replication Routing Indexes for XML, in DBISP2P workshop 2007.

• K. Stefanidis, E. Pitoura, P. Vassiliadis. A Context-Aware Preference Database System. Journal of Pervasive Computing and Communications, vol. 3, no. 4, pp. 439-460, 2007. Emerald Group Publishing Ltd, ISSN 1742-7371.

• E. Leontiadis, V.V. Dimakopoulos and E. Pitoura. Creating and Maintaining Replicas in Unstru ctured Peer-to-Peer Systems, EURO-PAR 2006

• V. V. Dimakopoulos and E. Pitoura. On the Performance of Flooding-Based Resource Discovery IEEE TPDS, 17(11) pg 1242-1252, Nov 2006.

• K. Stefanidis, E. Pitoura and P. Vassiliadis. Modeling and Storing Context-Aware Preferences. ADBIS 2006.

• G. Koloniari and E. Pitoura. Workload-Aware Clustering of XML Peers. ISYC 2006.

• G. Koloniari, Y. Petrakis, E. Pitoura and T. Tsotsos. Workload-Aware Overlay Construction Using Histograms. CIKM 2005.

• F. Papadopoulos, A. Zarras, P. Vassiliadis and E. Pitoura. Timely Provisioning of Mobile Services in Critical Pervasive Environments. In Proceedings of the 7th International Symposium on Distributed Objects and Applications (DOA'05), 2005.

• Z.Plitsis, I. Fudos, E. Pitoura, A. Zarras. On Accessing GSM-enabled Mobile Sensors. In Proceedings of the 2nd IEEE International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP'05), 2005.

• A. Karakasidis, P. Vassiliadis and E. Pitoura, ETL Queues for Active Data Warehousing. 2nd International Workshop on Information Quality in Information Systems (IQIS 2005), Co-located with ACM SIGMOD/PODS 2005 Baltimore, MD, USA, June 17, 2005

• A. Zarras, P. Vassiliadis and E. Pitoura, Query Management over Ad-Hoc Communities of Web Services. IEEE International Conference on Pervasive Services 2005, (ICPS'05) 11-14 July 2005, Santorini, Greece

• C. Skouteli, G. Samaras and E. Pitoura, Concept-Based Discovery of Mobile Services. 6th International Conference on Mobile Data Management, (MDM 2005), Agia Napa, Cyprus, May 2005

• K. Stefanidis, E. Pitoura and P. Vassiliadis On Supporting Context-Aware Preferences in Relational Database Systems. In Proceedings of the MDM 2005 Workshop on "Managing Context Information in Mobile and Pervasive Environments" (MCMP05), Ayia Napa. Cyprus, May 9 2005

• G. Koloniari and E. Pitoura, Peer-to-Peer Management of XML Data: Issues and Research Challenges. Sigmod Record, June 2005.

• E. Papapetrou, E. Pitoura, and K. Lillis, Speeding-up Cache Lookups in Wireless Ad-Hoc Routing using Bloom Filters, The 16th Annual International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC 2005), Sept 11-13, 2005, Berlin, Germany, 2005

• E. Leontiadis, V. V. Dimakopoulos and E. Pitoura, Cache Updates in a Peer-to-Peer Network of Mobile Agents. 4th IEEE International Conference on Peer-to-Peer Computing (P2P 2004), Zurich, Switzerland, August 2004

• Y. Petrakis and E. Pitoura, On Constructing Small Worlds in Unstructured Peer-to-Peer Systems. In the EDBT International Workshop on Peer-to-Peer Computing and Databases, Heraklion, Crete, Greece, March 14, 2004

• Y. Petrakis, G. Koloniari and E. Pitoura, On Using Histograms as Routing Indexes in Peer-to-Peer System. 2nd International Workshop on Databases, Information Systems and Peer-to-Peer Computing (DBISP2P), In conjunction with VLDB2004, August 29-30, Toronto, Canada

• O. Shigiltchoff, P. K. Chrysanthis, E. Pitoura, "Energy Efficient Access in Multiversion Broadcast Environment". Mobile Data Management 2004, page 168 (short paper)

• G. Koloniari and E. Pitoura, Content-Based Routing of Path Queries in Peer-to-Peer Systems, EDBT 2004

• C. Skouteli, C. Panayiotou, G. Samaras and E. Pitoura, Communities: Concept-Based Querying for Mobile Services. Global Computing 2004, LNCS Springer 2005, pp 59-76

• K. Karenos, G. Samaras, P. K. Chrysanthis, E. Pitoura, Mobile agent-based services for view materialization. Mobile Computing and Communications Review 8(3): 32-43 2004

• C. Spyrou, G. Samaras, E. Pitoura and P. Evripidou, Mobile Agents for Wireless Computing: The Convergence of Wireless Computation Models with Mobile Agent Technologies. ACM/Baltzer MONET, Volume 9, No 5, Oct 2004.

• G. Koloniari and E. Pitoura, Filters for XML-based Service Discovery in Pervasive Computing The Computer Journal , Volume 47, No 4, July 1004, pp 461-474

• O. Schigiltchoff, P. K. Chrysanthis and E. Pitoura. Adaptive Multiversion Broadcast Organization, Information Systems, Volume 29, Issue 6, Pages 509-528, Sept 2004

• G. Koloniari, Y. Petrakis and E. Pitoura, Content-Based Overlay Networks of XML Peers Based on Multi-Level Bloom Filters, VLDB International Workshop on Databases, Information Systems and P2P Computing (DBISP2P), Sept 2003

• G. Koloniari and E. Pitoura, Bloom-Based Filters for Hierarchical Data, 5th Workshop on Distributed Data Structures and Algorithms (WDAS), July 2003 Proceeding in Informatics 19, Carleton Scientific.

• V. V. Dimakopoulos and E. Pitoura, A Peer-to-Peer Approach to Resource Discovery in Multi-Agent Systems. CIA 2003. ppt
  Extended version, University of Ioannina, TR2003-09.

• V. V. Dimakopoulos and E. Pitoura, Performance Analysis of Distributed Search in Open Agent Systems, International Parallel and Distributed Processing Symposium (IPDPS), Nice, France, April 2003

• E. Pitoura, P. K. Chrysanthis and K. Ramamritham. Characterizing the Temporal and Semantic Coherency of Broadcast-based Data Dissemination. Proc. of the International Conference on Database Theory (ICDT), January 2003.

• G. Kastidou, E. Pitoura, and G. Samaras, A Scalable Hash-Based Mobile Agent Location Mechanism. ICDCS Workshops 2003, May 19 - 22, 2003, Pr ovidence, Rhode Island, USA , IEEE Computer, pp 472-4793

• G. Samaras, K. Karenos, P. K. Chrysanthis, E. Pitoura, ViSMA: Extendible, Mobile-Agent Based Services for the Materialization and Maintenance of Personalized and Shareable Web Views. DEXA Workshops 2003: 974-979

• O. Shigiltchoff, P. K. Chrysanthis, E. Pitoura, Broadcast Data Organizations and Client Side Cache. ICDCS Workshops 2003

• E. Pitoura, S. Abiteboul, D. Pfoser, G. Samaras, M, Vazirgiannis, DBGlobe: A Service-Oriented P2P System for Global Computing, Sigmod Record, 32(3): 77-82, 2003.

• D. Pfoser, E. Pitoura, and N. Tryfona Metadata Modeling in a Global Computing Environment, Proc. of the 10th ACM International Symposium on Advances in Geographic Information Systems, McLean, VA November 8-9, 2002.

• O. Shigiltchoff, P. Chrysanthis and E. Pitoura, Multi-version Data Broadcast Organizations. In Proceedings of the 6th East European Conference on Advances in Databases and Information Systems (ADBIS), September 2002, Bratislava, Sloavakia

• A. Karakasidis and E. Pitoura, DBGlobe: A Data-Centric Approach to Global Computing International Workshop on Smart Appliances and Wearable Computing (IWSAWC 2002) In conjuction with ICDCS 2002, Vienna, Austria, July 2002

• Y. Villate, A. Illarramendi, and E. Pitoura, "Agent-Based and Mobile External Storage for Users of Mobile Devices", Workshop on Ubiquitous Agents on Embedded, Wearable, and Mobile devices (UbiAgents), held in conjunction with the 2002 Conf. on Autonomous Agents & Multiagent Systems (AMAS), Bologna, July 2002 (online proceedings)

• G. Samaras, C. Spyrou, E. Pitoura, M. Dikaiakos, "Tracker: A Universal Location Management System fo r Mobile Agents." European Wireless 2002 Conference. Next Generation Wireless Networks: Technologies , Protocols, Services and Applications, Florence, Italy, February 25-28, 2002.

• G. Samaras, C. Spyrou and Evaggelia Pitoura, View Generator (VG): A Mobile Agent Based System for the Creation and Maintenance of Web Views. In Proceedings of 7th IEEE Symposium on Computers and Communications, (ISCC 02) Taormina, Italy, July 2002

• I. Fudos, L. Palios, E. Pitoura. Geometric-Similarity Retrieval in Large Image Bases. ICDE 2002

• E. Pitoura and P. Chrysanthis Multiversion Data Broadcast, IEEE Transactions on Computers 51(10):1224-1230, October, 2002

• Y. Villate, A. Illarramendi, and E. Pitoura, On Keeping Data Safe and Available while Roaming. ACM/Baltzer MONET, 7(4), pp 315-328, August 2002

• V.V Dimakopoulos, T. Kinalis, S. Mastrogiannakis, and E. Pitoura, ``The SMart Autonomous Storage (SMAS) System'', In the 2001 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing (PARCIM2001), pp 303-306, August 26-28, 2001, Victoria, B.C., Canada.

• C. Spyrou, G. Samaras, E. Pitoura, S. Papastavrou, P. K. Chrysanthis, The Dynamic View System (DVS): Mobile Agents to Support Web Views, (demo). In the 17h International Conference on Data Engineering (ICDE01), Heidelberg, Germany, April 2-6, 2001.

• E. Bertino, E. Ferrarri, and E. Pitoura. An Access Control Mechansim for Large Scale Data Dissemination Systems. In RIDE 2001 Workshop.

• P. Evripidou, C. Panayiotou, G. Samaras, and E. Pitoura, The PaCMAn Metacomputer: Parallel Computing with Java Mobile Agents, Future Generation Computer Systems Journal, Special Issue on Java in High Performance Computing. 18 (2), pp 265-280, October 2001

• S. Papastavrou, P. K. Chrysanthis, G. Samaras and E. Pitoura, An Evaluation of the Java-based Approaches to Web Database Access. International Journal of Cooperative Information Systems. 10(4), pp 401--422, 2001

• A. Tsalgatidou and E. Pitoura, Business Models and Transactions in Mobile Electronic Commerce: Requirements and Properties. Computer Networks, 37(2), pp 221--236, Special Issue on Electronic Business Systems, October 2001.

• E. Pitoura and G. Samaras, Locating Objects in Mobile Computing. IEEE Transaction on Knowledge and Data Engineering, 13(4), pp 571-592, 2001.

• E. Pitoura and I. Fudos, Distributed Location Databases for Tracking Highly Mobile Objects, The Computer Journal, 44(2), pp 75-91, 2001

• A. Tsalgatidou, J. Veijalainen, and E. Pitoura. Challenges in Mobile Electronic Commerce. In the 3rd International Conference on Innovation through E-Commerce, November 14th-16th, 2000, Manchester UK.

• Y. Villate, A. Illarramendi, and E. Pitoura, Data Lockers: Mobile-Agent Based Middleware for the Security and Availability of Roaming Users Data In CoopIS 2000.

• S. Papastavrou, P. K. Chrysanthis, G. Samaras and E. Pitoura, An Evaluation of the Java-based Approaches to Web Database Access, In CoopIS 2000 .

• V. V. Dimakopoulos, A. Kinalis, E. Pitoura, and I. Tsoulos, On Deploying and Executing Data-Intensive Code on SMart Autonomous Storage (SMaS) Disks, In ADBIS-DASFAA Symposium on Advances in Databases and Information Systems , 2000.

• S. Madria, B. Bhargava, E. Pitoura and V. Kumar ``Data Organization Issues for Location Dependent Queries in Mobile Computing'', In ADBIS-DASFAA Symposium on Advances in Databases and Information Systems , 2000.

• G. Samaras, P. Evripidou and E. Pitoura, A Mobile-Agent Based Infrastructure for eWork and Ebussiness Application In the Proceedigns of the E-business and E-work Conference, Madrid, Spain, 18-20 October 2000.

• Y. Villate, E. Pitoura, A. Illarramendi and A. K. Elmagarmid, Extending the Data Services of Mobile Computers by External Data Lockers. In DEXA2000 International Workshop on Mobility in Databases and Distributed Systems.

• S. Papastavrou, G. Samaras and E. Pitoura, Mobile Agents for World Wide Web Distributed Database Access IEEE Transactions on Knowledge and Data Engineering, 12(5), pp 802-820, 2000

• E. Pitoura and P. K. Chrysanthis, Exploiting Versions for Handling Updates in Broadcast Disks, in Proceedings of VLDB 1999. pp. 114-125, Sept 1999.

• D. Barelos, E. Pitoura, and G. Samaras, Mobile Agent Procedures: Metacomputing in Java, in Proceedings of the ICDCS Workshop on Middleware, 1999.

• P. Evripidou, G. Samaras, E. Pitoura, and C. Panayiotou, PaCMAn Mobility for High Performance Computing in Java for High-Performance Computing Workshop in conjunction with the 1999 ACM Int. Conf. on Supercomputing June 1999.

• C. Panayiotou, G. Samaras, E. Pitoura, and P. Evripidou, Parallel Computing Using Java Mobile Agents in 25th Euromicro Conference Special session on Network Computing September 1999.

• C. Spyrou, G. Samaras, E. Pitoura, and P. Evripidou, Wireless Computational Models: Mobile Agents to the Rescue, in DEXA Workshop , 1999.

• E. Pitoura and P. K. Chrysanthis, Scalable Processing of Read-Only Transactions in Broadcast Push Proceedings of the 19th IEEE International Conference on Distributed Computing System pp. 432-441.

  long-version

• S. Papastavrou, G. Samaras and E. Pitoura, Mobile Agents for Distributed WWW Access, Proceedings of the 15th International Conference on Data Engineering (ICDE99), March 1999 Best Paper Award .

• E. Pitoura and B. Bhargava, Data Consistency in Intermittently Connected Distributed Systems. IEEE Transaction on Knowledge and Data Engineering , 11(6), pp 896-915, Nov/Dec 1999.

• E. Pitoura, Scalable Invalidation-Based Processing of Queries in Broadcast Push-Based Delivery, Proceedings of the Mobile Data Access Workshop, in coopeation with the 17th International Conference on Conceptual Modeling (ER'98). In Advances in Database Technologies, Vol. 1, pp. 230--240, LNCS Vol. 1552, Spinger Verlag 1999.
  An extended version (including proofs of theorems) appears as: University of Ioannina, Computer Science Department, Techical Report No: 98-21
  

• E. Pitoura and I. Fudos, An Efficient Hierarchical Scheme for Locating Highly Mobile Users, Proceedings of the 6th ACM International Conference on Information and Knowledge Management (CIKM98), November 1998, pp 218-225.
  An extended version appears as University of Ioannina, Computer Science Department, Techical Report No: 98-02

• E. Pitoura, Supporting Read-Only Transactions in Wireless Broadcasting Proceedings of the DEXA98 International Workshop on Mobility in Databases and Distributed Systems, August 1998, IEEE Computer Society, pp 428-433.
  

• E. Pitoura, Transaction-Based Coordination of Software Agents Proceedings of the 9th International Conference on Database and Expert Systems Applications (DEXA), August 1998, Springer Verlag, LNCS 1460, pp 460-469.
  

• E. Pitoura, A. Zhang and B. Bhargava, On Relaxing Serializability by Constraining Transaction Readsets Information Systems, Vol. 22, No. 6, pp 387--400, 1997.

• E. Pitoura, Providing Database Interoperability through Object-Oriented Language Constructs, Journal of Systems Integration, Vol. 7, No. 2, pp. 99--126, August 1997.

• I. Fudos, E. Pitoura and W. Szpankowski, On Pattern Occurrences in a Random Text, Information Processing Letters, Vol. 57, No. 6, pp. 307-312, March 1996.

• E. Pitoura, A Replication Schema to Support Weak Connectivity in Mobile Information Systems Proceedings of the 7th International Conference on Database and Expert Systems Applications (DEXA) , September 1996.
  An extended version appears as: University of Ioannina, Computer Science Department, Techical R eport No: 96-08
  Slides of the presentation at the DEXA Conference, September 1996.

• E. Pitoura, A. Zhang and B. Bhargava, A View-based Approach to Relaxing Global Serializability in a Multidatabase System, Proceedings of the 14th Annual ACM Symposium on the Principles of Distributed Computing (PODC95), August 1995.

• E. Pitoura and B. Bhargava, Maintaining Consistency of Data in Mobile Distributed Environments Proceedings of the 15th International Conference on Distributed Computing Systems, pp. 404--413, May 1995.
  Slides of the presentation at the DCS Conference, May 1995.

• E. Pitoura, ``Extending an Object-Oriented Programming Language to Support the Integration of Multidatabase Systems'', Proceedings of the 28th IEEE Annual Hawaii International Conference on System Sciences (HICSS-28), pp. 707--716, January 1995.

• E. Pitoura and B. Bhargava, Revising Transaction Concepts for Mobile Computing 1st IEEE Workshop on Mobile Computing Systems and Applications (MCSA94), pp. 164--168, December 1994. An one-page abstract appears also in TCOS Bulletin, Spring 1995.

• E. Pitoura, O. Bukhres and A. Elmagarmid, Object-Orientation in Multidatabase Systems, ACM Computing Surveys, Vol. 27, No 2, pp. 141--195, June 1995.

• A. Elmagarmid and E. Pitoura, Using Object-Oriented Technology for Database Integration, IEEE Computer, pp. 67--68, October 1995.

• B. Bhargava, M. Anammalai, and E. Pitoura, Digital Library Services in Mobile Computing, Sigmod Record , Vol. 24, No 4, pp. 34--39, Invited Paper, Special Issue on Mobile Computing, December 1995.

• E. Pitoura and B. Bhargava, A Framework for Providing Consistent and Recoverable Agent-Based Access to Heterogeneous Mobile Databases, Sigmod Record , Vol. 24, No 3, pp. 44--49, September 1995.

• E. Pitoura and B. Bhargava, Building Information Systems for Mobile Environments 3rd ACM International Conference on Information and Knowledge Management (CIKM94), pp. 371--378, November 1994.

• B. Bhargava, S. Goel, S. Li and E. Pitoura, Communication Issues for Digital Libraries in Wide Area Networks, IEEE Workshop on Digital Libraries: Current Issues, New Jersey, May 1994.

Computer Science Conference Ranking

Acceptance Rates of Major Database Conferences

• E. Pitoura, C. Turker and G. Samaras, "Seamless Consistency", In "Mobile Middleware", P. Bellavista and A Corradi, eds, CRC Press (In press)

• E. Pitoura and G. Samaras, Mobile Computing, In the Encyclopedia of Distributed Computing, J. Urban and P. Dasgupta, eds, Kluwer Academic Publishers, (To be published).

• E. Pitoura, G. Samaras, and G. Kastidou, "Locating Mobile Objects", In Handbook of Mobile Computing, Imad Mahgoub and Mohammad Ilyas, eds, CRC Press, 2004

• O. Bukhres, E. Pitoura and A. Zaslavsky, ``Mobile Computing'', In: Vol.3 Handbook on Data Management in Information Systems , J.Blazewicz, W.Kubiak, T. Morzy, M.Rusinkiewicz eds, ISBN:3540438939, Springer Verlag, 2003

• E. Pitoura, O. Bukhres and A. Elmagarmid, Object-Oriented Multidatabase Systems: An Overview, in Object-Oriented Multidatabases: A Solution for Advanced Applications , Omran Bukhres and Ahmed Elmagarmid eds, Prentice Hall, 1996.

• B. Bhargava, M. Anammalai, S. Goel, S. Li, E. Pitoura, A. Zhang and Z. Zhang, DL-Raid: An Environment for Supporting Digital Library Services, in Issues in Digital Libraries , Nabil Adams, Bharat Bhargava, and Yelena Yesha, eds, LNCS 916, pp. 281--300, Springer Verlag, 1995.

• G. Koloniari and E. Pitoura, Routing Path Queries in Peer-to-Peer Systems, 2nd Hellenic Database Symposium, (HDMS 2003), Athens, September 2003

• E. Pitoura and I. Fudos, A Hierarchical Scheme for Locating Mobile Users, in 6th Hellenic Conference on Informatics, Athens, Greece, December 1997.

• S. Papastavrou, P. K. Chrysanthis, G. Samaras and E. Pitoura, A Survey on the Java-based Approaches for Web Database Connectivity, in the 10th Mediterranean Electrotechnology Conference (MELECON), 2000

• X. Liu, E. Pitoura and B. Bhargava, Adapting Distributed Database Systems for High Availability, Technical Report CSD 95-013, Computer Science Department, Purdue University, 1995.

• E. Pitoura and B. Bhargava, Dealing with Mobility: Issues and Research Challenges, Technical Report CSD 93-070, Computer Science Department, Purdue University, 1993.