AFFILIATION: Assistant Professor
CONTACT DETAILS
Informatics Laboratory
Agricultural University of Athens
Iera Odos 75
GR 118 55 Athens
Greece
Tel : +(01) 529 4175, 529 4172
Fax : +(01) 529 4199
Email: lorentzos@auadec.aua.ariadne-t.gr
STUDIES
BSc Mathematics, University of Athens
MSc (Computer Science), Queens College, CUNY, USA
PhD (Computer Science), Birkbeck College, University of London
RESEARCH INTERESTS
Data Modelling, Temporal Databases, Spatial Database Systems, Image Processing.
EXTERNAL RECOGNITION
Research results are currently potential ISO SQL standards.
PROJECTS
CHOROCHRONOS (in progress)
Description: Integration of research in temporal and spatial database systems for the design and implementation of a Spatiotemporal DBMS.
Contribution:
INTERVAL DATABASES (in progress)
Description: Formalisation of query languages for the management of interval data and investigation of relevant research problems.
Contribution: Project leader
Initiation : December 1995
Duration : 2 years
Funding : Agricultural University of Athens
MACQU (in progress)
Description: Development of system to automate the management and control in green houses.
Contribution: Involvement in system software specification.
Initiation : January 1994
Duration : 4 years
Funding : European Union (AIR II)
ORES (completed)
Description: Development of temporal DBMS and relevant CASE tools.
Contribution:
GIS FOR LAND RESOURCES ASSESSMENT (completed)
Description : Development of GIS for land uses.
Contribution:
BARBARA (terminated)
Description: System for plant disease telediagnosis.
Contribution: System analysis and design, programs specification (completed).
Initiation : March 1992
Termination: January 1993
Funding : European Union (RACE)
CHRONOBASE (completed)
Description: Investigation of research problems in active, temporal and spatial databases.
Contribution: Involvement in research issues from the perspective of temporal databases.
Initiation : 1994
Duration : 2 years
Funding : Greek Secretariat of Research and Technology (PENED)
PUBLICATIONS (part of them)
Citations to publications exceed 100.
N. A. Lorentzos, Y. G. Mitsopoulos, SQL Extension for Interval Data. IEEE Transactions on Knowledge and Data Engineering 9(3), 1997, 480-499.
N. A. Lorentzos, H. Darwen, Extension to SQL2 Binary Operations for Temporal Data. Invited paper, Proc. 3rd HERMIS Conference, Athens, 26-28 Sept. 1996, 462-469.
N. A. Lorentzos, Y. Manolopoulos, Functional Requirements for Historical and Interval Extensions to the Relational Model. Data and Knowledge Engineering 17, 1995, 59-86.
N. A. Lorentzos, A. Poulovassilis, C. Small, Manipulation Operations for an Interval-Extended Relational Model. Data and Knowledge Engineering 17, 1995, 1-29.
C. Vassilakis, N. A. Lorentzos, P. Georgiadis, Transaction Support in a Temporal DBMS. Proc. Int. Workshop on Temporal Databases, Zurich, 17-18 Sept. 1995 (in Recent Advances in Temporal Databases, ed. J. Clifford, A. Tuzhilin, pub. Springer), 1995, 255-271.
The SQL2 Temporal Language Design. The TSQL2 Language Committee, R. Snodgrass, I. Ahn, G. Ariav, D. Batory, J. Clifford, C. Dyreson, R. Elmasri, F. Grandi, C. Jensen, W. Kafer, N. Kline, K. Kulkarni, T. Leung, N. Lorentzos, J.Roddick, A. Segev, M. Soo, S. Sripada, ed. R. Snodgrass, pub. Klower, 1995.
N. A. Lorentzos, A. Poulovassilis, C. Small, Implementation of Update Operations for Interval Relations. Computer Journal 37(3), 1994, 163-176.
C. Jensen, J. Clifford, R. Elmasri, S. Gadia, P. Hayes, S. Jajodia (editors), C. Dyreson, F. Grandi, W. Kafer, N. Kline, N. Lorentzos, Y. Mitsopoulos, A. Montanari, D. Nonen, E. Peressi, B. Pernici, J. Roddick, N. Sarda, M. Scalas, A. Segev, R. Snodgrass, M. Soo, A. Tansel, P. Tiberio, G. Wiederhold, A Concensus Glossary of Temporal Database Concepts. SIGMOD Record, 23(1), March 1994, 52-64.
R. Snodgrass, I. Ahn, G. Ariav, D. Batory, J. Clifford, C. Dyreson, R. Elmasri, F. Grandi, C. Jensen, W. Kafer, N. Kline, K. Kulkarni, T. Leung, N. Lorentzos, J.Roddick, A. Segev, M. Soo, S. Sripada, TSQL2 Language Specification. SIGMOD Record, 23(1), March 1994, 65-96.
R. Snodgrass, I. Ahn, G. Ariav, D. Batory, J. Clifford, C. Dyreson, R. Elmasri, F. Grandi, C. Jensen, W. Kafer, N. Kline, K. Kulkarni, T. Leung, N. Lorentzos, J.Roddick, A. Segev, M. Soo, S. Sripada, A TSQL2 Tutorial. SIGMOD Record, 23(3), September 1994, 27-33.
N. A. Lorentzos, DBMS Support for Non-Metric Measurement Systems. IEEE Transactions on Knowledge and Data Engineering 6(6), December 1994, 945-953.
Y. Manolopoulos, N. A. Lorentzos, Performance of Linear Hashing for Primary Key Retrieval. Information Systems 19(5), 1994, 433-446.
N. A. Lorentzos, Y. Manolopoulos, Efficient Management of 2-Dimensional Interval Relations, Proc. 5th DEXA Int. Conf., Athens, Sep. 1994, in Lecture Notes in Computer Science (ed. D. Karagiannis), Pub. Springer-Verlag, 1994, 72-82.
N. A. Lorentzos, Axiomatic Generalization of the Relational Model to Support Valid Time Data. Proc. International Workshop on an Infrastructure for Temporal Databases, ed. R. Snodgrass, Arlington, Texas, 14-16 June 1993, W1-W16.
N. A. Lorentzos, Y. G. Mitsopoulos, IXSQL: An Interval Extension to SQL. Proc. International Workshop on an Infrastructure for Temporal Databases, ed. R. Snodgrass, Arlington, Texas, 14-16 June, 1993, PP1-PP14.
N. A. Lorentzos, Y. Manolopoulos, Optimised Update of 2-Dimensional Interval Relations, Proc. 4th Panhellenic Conference of Greek Computer Society, Patra, 16-18 December, 1993, 21-33.
The Interval Extended Relational Model and its Application to Valid Time Databases. Chapter 3 in book Temporal Databases: Theory, Design and Implementation, ed. A. Tansel, J. Clifford, S. Gadia, A. Segev, R. Snodgrass, Publisher Benjamin / Cummings, USA, 1993, 67-91
C. Jensen (editor), J. Clifford, S. Gadia, F. Grandi, P. Kalua, N. Kline, N. Lorentzos, Y. Mitsopoulos, A. Montanari, S. Nair, E. Peressi, B. Pernici, E. Robertson, J. Roddick, N. Sarda, M. Scalas, A. Segev, R. Snodgrass, A. Tansel, P. Tiberio, A. Tuzhilin, G. Wuu, A Consensus Test Suite of Temporal Database Queries. Internal Report R 93-2034, Aalborg University, ISSN 0908-1216, 45 pages, November 1993, 45 pages.
C. Jensen, J. Clifford, R. Elmasri, S. Gadia, P. Hayes, S. Jajodia (editors), C. Dyreson, F. Grandi, W. Kafer, N. Kline, N. Lorentzos, Y. Mitsopoulos, A. Montanari, D. Nonen, E. Peressi, B. Pernici, J. Roddick, N. Sarda, M. Scalas, A. Segev, R. Snodgrass, M. Soo, A. Tansel, P. Tiberio, G. Wiederhold, A Concensus Glossary of Temporal Database Concepts. Internal Report R 93-2035, Aalborg University, ISSN 0908-1216, November 1993, 55 pages.
N. A. Lorentzos, DBMS Support for Time and Totally Ordered Compound Data Types. Information Systems 17(5), Sept. 1992, 347-358.
N. A. Lorentzos, G. Mitsopoulos, Query Language for the Management of Interval Data, Proc. 1st HERMIS Conference, Athens, 25-26 Sept. 1992, 137-144.
N. A. Lorentzos, A. B. Sideridis, Valid-Time Information Systems in Agricultural Cooperatives. Proc. Agricultural Co-operatives and Development Agencies: Integrated Information Infrastructure, Athens 26-27 Nov. 1992.
N. A. Lorentzos, V. J. Kollias, The Handling of Depth and Time Intervals in Soil Information Systems. Computers and Geosciences, 15(3) 1989, 395-401.
N. A. Lorentzos, R. G. Johnson, Åxtending Relational Algebra to Manipulate Temporal Data. Information Systems 13(3), 1988, 289-296.
N. A. Lorentzos, R. G. Johnson, Requirements Specification for a Temporal Extension to the Relational Model, IEEE / Data Engineering, 11(4), 1988, 26-33 (invited author).
N. A. Lorentzos, R. G. Johnson, TRA Á Model for a Temporal Relational Algebra. Proc. Temporal Aspects in Information Systems, Sophia-Antipolis, France, 13-15 May 1987 (in Temporal Aspects in Information Systems, ed. C. Rolland, F. Bodart, M. Leonard, pub. North-Holland), 1988, 203-215.
N. A. Lorentzos, R. G. Johnson, An Extension of the Relational Model to Support Generic Intervals. Proc. Int. Conf. Åxtending Database Technology, Venice, Italy, 13-15 March 1988 (in Advances of Database Technology-EDBT'88 ed. J.W. Schmidt, S. Ceri, M. Missikoff, Springer-Verlag), 1988, 528-542.
R. G. Johnson, N. A. Lorentzos, Temporal Data Management. Information Update, Database Technology 1, 1987, 5-11.
OTHER ACTIVITIES
MEMBERSHIP: Greek Mathematics Society, Greek Computer Society, BCS, ACM
Last update: August 22, 1997
PROJECT CHOROCHRONOS
Project Title: A Research Network for Spatiotemporal Database Systems
Contract Number: ERBFMRXCT960056
Job Description: Two (2) Post-Doctoral Researchers in Computer Science, preferably aged 35 years or less, with research interests in Geographic Information Systems and / or (Temporal) Databases. The researcher will participate in current research activities related to spatial and temporal database systems.
Duration and Start Date: Immediately
Place of Work: Informatics Laboratory, Agricultural University of Athens
Contact Person: Prof. Nikos Lorentzos
Agricultural University of Athens
Informatics Laboratory
Iera Odos 75
GR 118 55 Athens
Greece
Phone: +30 1 529 4175
Fax : +30 1 529 4199
E-mail: lorentzos@auadec.aua.ariadne-t.gr
Project Home Page:http://www.dbnet.ece.ntua.gr/projects/chorochronos.html
ISO STANDARDS FOR SQL/TEMPORAL
The SQL/Temporal project arose out of an approach in 1994 by the TSQL2 committee to the ANSI database committee (formerly X3H2, now NCITS H2). Specifically, certain proposals from the TSQL2 committee were forwarded to the ISO Database Languages (DBL) committee by the ANSI committee in 1995 and 1996, but none of them was ever accepted. The United Kingdom delegates showed particular interest in the subject and were mainly responsible for raising the concerns about the TSQL2 approach. In response to a specific question to the TSQL2 chairman (about generalizing temporal operators to periods over any ordered type), the United Kingdom delegates were put in touch with the authors of another approach. This led to the UK writing proposals for SQL/Temporal during the same period (1995-96) which were accepted by a significant majority of the ISO DBL national body delegates. A list of proposals related to SQL/Temporal are listed below and are available via anonymous ftp from
jerry.ece.umassd.edu/isowg3/dbl/LLLdocs/LLLnnn.ps
where LLL is a three character string denoting the code of the ISO Committee meeting place (e.g. LHR - London, MAD -Madrid, MCI - Kansas City etc ) and nnn is the paper number.
It presents an SQL extension which supports temporal (valid time) data. Attached to this is an early version of the paper
N. A. Lorentzos, Y. G. Mitsopoulos, SQL Extension for Interval Data. IEEE Transactions on Knowledge and Data Engineering 9(3), 1997, 480-499.
It proposes the inclusion of a new SQL clause, NORMALIZE.
(Approved by the ISO Committee.)
It proposes a new data type, PERIOD OF TIMESTAMP(N).
(Approved by the ISO Committee.)
It proposes the support of two new SQL data types, PERIOD OF TIME and PERIOD OF DATE.
(Approved by the ISO Committee.)
Amongst others, it proposes an extension to the NORMALIZE clause.
(Approved by the ISO Committee.)
It proposes an extension to the SQL binary operations UNION, EXCEPT and INTERSECT, for the management of temporal data.
(Approved by the ISO Committee.)
It proposes the support of a new SQL data type, PERIOD OF INTEGER.
(Approved by the ISO Committee.)
Amongst others, it proposes an extension to the NORMALIZE clause.
(Approved by the ISO Committee.)
It presents a roadmap towards the complete support of temporal data
(Not discussed yet in the ISO Committee.)
For the SQL/Temporal working draft, look at .sql4-archived-temporal.ps via anonymous ftp from
jerry.ece.umassd.edu/isowg3/dbl/BASEdocs/sql4hold.