Hostname: page-component-6766d58669-mzsfj Total loading time: 0 Render date: 2026-05-24T01:07:54.942Z Has data issue: false hasContentIssue false

Extending relational algebra with similarities

Published online by Cambridge University Press:  25 April 2012

MELITA HAJDINJAK
Affiliation:
Faculty of Electrical Engineering, University of Ljubljana, Slovenia Email: Melita.Hajdinjak@fe.uni-lj.si
GAVIN BIERMAN
Affiliation:
Microsoft Research, Cambridge, United Kingdom Email: gmb@microsoft.com

Abstract

In this paper we propose various extensions to the relational model to support similarity-based querying. We build upon the -relation model, where tuples are assigned values from an arbitrary semiring , and its associated positive relational algebra . We consider a recently proposed extension to using a monus operation on the semiring to support negative queries, and show how, surprisingly, it fails for important ‘fuzzy’ semirings. Instead, we suggest using a negation operator. We also consider the identities satisfied by the relational algebra . We show that moving from a semiring to a particular form of lattice (a De Morgan frame) yields a relational algebra that satisfies all the classical (positive) relational algebra identities. We claim that to support real-world similarity queries realistically, one must move from tuple-level annotations to attribute-level annotations. We show in detail how our De Morgan frame-based model can be extended to support attribute-level annotations and give worked examples of similarity queries in this setting.

Information

Type
Paper
Copyright
Copyright © Cambridge University Press 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable