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Re: [PRD] PRD Review By Example

From: Christian de Sainte Marie <csma@ilog.fr>
Date: Fri, 24 Oct 2008 15:51:43 +0200
Message-ID: <4901D2EF.7040408@ilog.fr>
To: Gary Hallmark <gary.hallmark@oracle.com>
CC: rif WG <public-rif-wg@w3.org>

Gary Hallmark wrote:
> 
> I'm not asking for a special PRD construct.  Note that my example 
> ruleset is a Core ruleset:
> 
> Prefix(p someIRI)
> p:A(0)
> (* r1 *)Forall ?x (p:A(?x) :- p:A(External(func:numeric-minus(?x 1))))
> 
> Surely you agree we must handle the initial fact p:A(0)

I surely agree that we must handle rules that consist of unconditional actions, including when the unconditional action is the assertion of a ground atom, as we do it alread.

According to the current syntax and semantics, p:A(0) is a single action, which is a construct of the RULE abstract class. It corresponds to a fact in BLD, which is, semantically, a ground head without a body (gory, isn't it?), that is, a rule where the tautological condition is left implicit and the conclusion is ground.

The same works for PRD, but that explanation is left implicit. I will correct that in the abstract syntax for rules and make it explicit in the semantics as well (it was explicit in the FPWD, where there where specific rules in the operational semantics to handle that case). By Monday night (27 Oct).

Cheers,

Christian
Received on Friday, 24 October 2008 13:52:32 GMT

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