ISSUE-76: Equality in Core?

Equality in Core?

State:
CLOSED
Product:
Core
Raised by:
Jos de Bruijn
Opened on:
2008-09-02
Description:
There is already a widespread consensus that Core will not allow equality in the rule heads.

The question which remains: Will Core allow equality in the rule bodies?
It is known that introducing equality in rule bodies does not increase expressiveness: rules with equality in the body can be straightforwardly equivalently (i.e., they have the same models) rewritten to rules without equality. So, equality in the body is simply a syntactic shortcut.

It is argued in [1] that a restricted form of equality should be allowed in the rule bodies to facilitate external function calls. However, as mentioned above, this equality is not necessary. It is simply a syntactic shortcut.


So, we basically have three choices:
a) allow equality in rule bodies
b) allow only a restricted form of equality in rule bodies, as argued in [1]
c) not allow equality in rule bodies


To me personally, (b) does not make sense. Why allow equation of variables and functions, but not variables and variables?
So, I argue that we should either (a) allow or (c) disallow equality in rule bodies.


[1] http://www.w3.org/2005/rules/wiki/Core#Intersection_of_RIF-PRD_and_RIF-BLD
Related Actions Items:
No related actions
Related emails:
  1. [ADMIN] Minutes of 23 September 2008 RIF Telecon (from leora@us.ibm.com on 2008-09-29)
  2. [Admin] Agenda for RIF telecon 23 Sept (from csma@ilog.fr on 2008-09-22)
  3. Re: ISSUE-76: Equality in Core? [Core] (from der@hplb.hpl.hp.com on 2008-09-14)
  4. Re: ISSUE-76: Equality in Core? [Core] (from kifer@cs.sunysb.edu on 2008-09-02)
  5. ISSUE-76: Equality in Core? [Core] (from sysbot+tracker@w3.org on 2008-09-02)

Related notes:

At F2F11, the WG resolved to close this issue, http://www.w3.org/2005/rules/wg/meeting/2008-09-27#resolution_5. The WG agreed that Core should keep unrestricted equality and external function and predicate calls in rule conditions and keep external functions calls in rule conclusions

Christopher Welty, 30 Sep 2008, 15:24:52

Display change log ATOM feed


Chair, Staff Contact
Tracker: documentation, (configuration for this group), originally developed by Dean Jackson, is developed and maintained by the Systems Team <w3t-sys@w3.org>.
$Id: 76.html,v 1.1 2013-02-08 09:09:37 vivien Exp $