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DBPL
1993
Springer
141views Database» more  DBPL 1993»
13 years 9 months ago
Some Properties of Query Languages for Bags
In this paper we study the expressive power of query languages for nested bags. We de ne the ambient bag language by generalizing the constructs of the relational language of Brea...
Leonid Libkin, Limsoon Wong
ICDE
1994
IEEE
103views Database» more  ICDE 1994»
13 years 9 months ago
A Multi-Set Extended Relational Algebra - A Formal Approach to a Practical Issue
The relational data model is based on sets of tuples, i.e. it does not allow duplicate tuples in a relation. Many database languages and systems do require multi-set place, the hi...
Paul W. P. J. Grefen, Rolf A. de By
PODS
1999
ACM
89views Database» more  PODS 1999»
13 years 9 months ago
Type Inference in the Polymorphic Relational Algebra
We give a polymorphic account of the relational algebra. We introduce a formalism of \type formulas" speci cally tuned for relational algebra expressions, and present an algo...
Jan Van den Bussche, Emmanuel Waller
WEBDB
2005
Springer
105views Database» more  WEBDB 2005»
13 years 10 months ago
On the Expressive Power of Node Construction in XQuery
In the relational model it has been shown that the flat relational algebra has the same expressive power as the nested relational algebra, as far as queries over flat relations ...
Wim Le Page, Jan Hidders, Philippe Michiels, Jan P...
PAKDD
2005
ACM
96views Data Mining» more  PAKDD 2005»
13 years 10 months ago
Kernels over Relational Algebra Structures
Abstract. In this paper we present a novel and general framework based on concepts of relational algebra for kernel-based learning over relational schema. We exploit the notion of ...
Adam Woznica, Alexandros Kalousis, Melanie Hilario
OTM
2005
Springer
13 years 10 months ago
Probabilistic Ontologies and Relational Databases
The relational algebra and calculus do not take the semantics of terms into account when answering queries. As a consequence, not all tuples that should be returned in response to ...
Octavian Udrea, Yu Deng, Edward Hung, V. S. Subrah...
ICDT
2007
ACM
143views Database» more  ICDT 2007»
13 years 11 months ago
Database Query Processing Using Finite Cursor Machines
We introduce a new abstract model of database query processing, finite cursor machines, that incorporates certain data streaming aspects. The model describes quite faithfully what...
Martin Grohe, Yuri Gurevich, Dirk Leinders, Nicole...
ICCSA
2007
Springer
13 years 11 months ago
An Automatic Correction Tool for Relational Algebra Queries
Abstract. Relational algebra is one of the main topics covered in undergraduate computer science database courses. In this paper, we present a web-based tool designed to automatica...
Josep Soler, Imma Boada, Ferran Prados, Jordi Poch...
DBPL
2007
Springer
91views Database» more  DBPL 2007»
13 years 11 months ago
Relational Completeness of Query Languages for Annotated Databases
Annotated relational databases can be queried either by simply making the annotations explicitly available along the ordinary data, or by adapting the standard query operators so ...
Floris Geerts, Jan Van den Bussche
IDEAS
2009
IEEE
142views Database» more  IDEAS 2009»
13 years 11 months ago
A magic approach to optimizing incremental relational expressions
This paper is concerned with a transformation-based approach to update propagation in an extended version of Codd’s relational algebra which allows for defining derived relatio...
Andreas Behrend