Papers by nikos lorentzos
Indexing moving objects usually involves a great amount of updates, caused by objects reporting t... more Indexing moving objects usually involves a great amount of updates, caused by objects reporting their current position. In order to keep the present and past positions of the objects in secondary memory, each update introduces an I/O and this process is sometimes creating a bottleneck. In this paper we deal with the problem of minimizing the number of I/Os in such a way that queries concerning the present and past positions of the objects can be answered efficiently. In particular we propose two new approaches that achieve an asymptotically optimal number of I/Os for performing the necessary updates. The approaches are based on the assumption that the primary memory suffices for storing the current positions of the objects.
Period-Stamped Temporal Models
1: Introduction.- 2: Ontology for Spatio-temporal Databases.- 3: Conceptual Models for Spatio-tem... more 1: Introduction.- 2: Ontology for Spatio-temporal Databases.- 3: Conceptual Models for Spatio-temporal Applications.- 4: Spatio-temporal Models and Languages: An Approach Based on Data Types.- 5: Spatio-temporal Models and Languages: An Approach Based on Constraints.- 6: Access Methods and Query Processing Techniques.- 7: Architectures and Implementations of Spatio-temporal Database Management Systems.- 8: Advanced Uses: Composing Interactive Spatio-temporal Documents.- 9: Spatio-temporal Databases in the Years Ahead.
Spatio-temporal SQL
Panhellenic Conference on Informatics, 2001
An extension of SQL is formalized for the management of spatio-temporal data, i.e. of spatial dat... more An extension of SQL is formalized for the management of spatio-temporal data, i.e. of spatial data that evolves with respect to time. The syntax and semantics of the extension is fully consistent with SQL. The formalism is very general, in that the extension can be applied to any kind of data, either temporal or spatial or conventional.
Tods, 1998
and Business This is a preliminary release of an article accepted by ACM Transactions on Database... more and Business This is a preliminary release of an article accepted by ACM Transactions on Database Systems. The de nitive version is currently in production at ACM and, when released, will supersede this version.
Acknowledgement The present work has been produced as part of the project ' Development of a Geog... more Acknowledgement The present work has been produced as part of the project ' Development of a Geographic Information System for Natural Resources Evaluation and Environmental Assessment' (No. 91ED449), funded by the Greek Secretariat of Research and Development. The authors are grateful to Professor Yassoglou for providing the soil data of the area.
Point-Stamped Temporal Models
Encyclopedia of Database Systems, 2009
Journal of Geographic Information and Decision Analysis, vol. 1, no. 2, pp. 89-99, 1997
We propose here an interpolation method based on a decomposition of the data in large-and small-s... more We propose here an interpolation method based on a decomposition of the data in large-and small-scale variation. This decomposition was performed using a two-way directional decomposition, similar to the decomposition used by Cressie in his median-polish kriging ...
A Research Network for Spatiotemporal Database Systems
Query language for the management of interval data
Extension to SQL2 binary operations for temporal data
Management of Intervals and Temporal Data in the Relational Model
G. Johnson, N. A. Lorentzos, Temporal Data Management
Extension to SQL2 data manipulation operations for interval data
The Interval Extended Relational Model and its Application to Valid Time Databases
Quantification of Informative Characters 1 Parsimony-Informative Characters
ABSTRACT
A time-extrinsic knowledge representation model
ABSTRACT
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Papers by nikos lorentzos