A Rational and Efficient Algorithm for View Revision in Databases

Abstract

The dynamics of belief and knowledge is one of the major components of any autonomous system that should be able to incorporate new pieces of information. In this paper, we argue that to apply rationality result of belief dynamics theory to various practical problems, it should be generalized in two respects: first of all, it should allow a certain part of belief to be declared as immutable; and second, the belief state need not be deductively closed. Such a generalization of belief dynamics, referred to as base dynamics, is presented, along with the concept of a generalized revision algorithm for Horn knowledge bases. We show that Horn knowledge base dynamics has interesting connection with kernel change and abduction. Finally, we also show that both variants are rational in the sense that they satisfy certain rationality postulates stemming from philosophical works on belief dynamics.

A new rational algorithm for view updating in relational databases

“…Now we recall an algorithm for revision based on abduction presented in [2,18], Some basic definitions required for the algorithm are presented first.…”

“…The general revision algorithm of [18] is reproduced here as Algorithm 1. The basic idea behind this algorithm is to generate all (locally minimal) explanations for the sentence to be contracted and determine a hitting set for these explanations.…”

“…Note that there are no facts in IDB * . So when we add a delete request such as ¬A to this, the added request is the only fact and any bottom-up reasoning strategy is fully focused on the goal (here the delete request) The next step is to consider the view insertion process [6] (unsuccessful branch -see [18]).…”

Comparative study of view update algorithms in rational choice theory

“…We begin by recalling previous work on view deletion. Chandrabose [6,7] and Delhibabu [34,35,36], defines a contraction and revision operator in view deletion with respect to a set of formulae or sentences using Hansson's [54] belief change. Similar to our approach, he focused on set of formulae or sentences in knowledge base revision for view update wrt.…”

“…The present paper provides a comparative study of view update algorithms in rational approach. ⋆ This paper extends work from Delhibabu [34] and Mayol [83] Our knowledge base dynamics is defined in two parts: an immutable part (formulae) and updatable part (literals) (for definition and properties see works of Nebel [88] and Segerberg [98]). Knowledge bases have a set of integrity constraints (see the definitions in later section).…”