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AW: [PRD] need Assign action

From: Adrian Paschke <adrian.paschke@biotec.tu-dresden.de>
Date: Wed, 18 Jun 2008 09:33:46 +0200
To: "'Gary Hallmark'" <gary.hallmark@oracle.com>, "'pu >> RIF WG'" <public-rif-wg@w3.org>
Message-Id: <20080618073337.8A64A70000FB@mailserver.biotec.tu-dresden.de>

Garry,

Yes we need it. Assign is what I called update or modify in yesterday's
telecon and in my PRD review.

It can not be simulated by a retract action followed by a new assert,
because if PRD has a negation (not) the retract might trigger a production
rule transition. But that is not the intended semantics of assign/update.

Just to clarify. We already have Equal for assignment to free variables in
the body of a rule. 

Informal semantics: ?X = Frame 
1. If ?X is free the frame will be bound (assigned) to ?X
2. If ?X is already bound it will be matched (check for equality) with the
Frame

So, the assign action semantically differs from single assignment via
equality.

-Adrian

-----Ursprüngliche Nachricht-----
Von: public-rif-wg-request@w3.org [mailto:public-rif-wg-request@w3.org] Im
Auftrag von Gary Hallmark
Gesendet: Dienstag, 17. Juni 2008 22:59
An: pu >> RIF WG
Betreff: [PRD] need Assign action


while editing PRD to change the examples to "real" presentation syntax, 
I see that I need an assign action.

I propose

syntax:  Assign ::= 'Assign' '(' frame ')'

informal semantics: triples which match the oid and slot name(s) given 
by the frame argument are removed from W, then the given frame is added to W
Received on Wednesday, 18 June 2008 07:34:32 GMT

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