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ISSUE-76: Equality in Core? [Core]

From: Rule Interchange Format Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Tue, 2 Sep 2008 16:47:16 +0000 (GMT)
To: public-rif-wg@w3.org
Message-Id: <20080902164716.29D3EBF4F@nelson.w3.org>


ISSUE-76: Equality in Core? [Core]

http://www.w3.org/2005/rules/wg/track/issues/76

Raised by: Jos de Bruijn
On product: Core

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 (b) disallow equality in rule bodies.
Received on Tuesday, 2 September 2008 16:47:49 GMT

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