W3C home > Mailing lists > Public > public-rif-wg@w3.org > January 2008

Re: model theory of error

From: Christian de Sainte Marie <csma@ilog.fr>
Date: Wed, 09 Jan 2008 13:57:12 +0100
Message-ID: <4784C4A8.6030008@ilog.fr>
To: Michael Kifer <kifer@cs.sunysb.edu>
CC: RIF WG <public-rif-wg@w3.org>

Michael Kifer wrote:

> How do you define an error independently of the evaluation strategy?
> What does it mean to say that "RIF does not mandate any 
> specific behaviour"? What is "behavior" exactly, if RIF (at least BLD) does
> not define any evaluation strategy?

Let me try without using the words "error" or "behaviour"...

An evaluated function is defined over a domain, and it is undefined 
outside of that domain.

If a function is used in a rule, we assume that any party that evaluates 
that rule knows the domain of the function, whether it is specified 
within RIF (builtin function) or not (application-specific).

So, anybody who may have to evaluate the function knows where it is 
defined and where it is not, and is able to check, before evaluating it, 
whether the arguments are in the domain, and the function defined, or not.

For the strict purpose of rule interchange, RIF needs to make sure that 
all users have the same understanding of the rule - that is, draw the 
same inferences - where the function is defined.

But does RIF need to guarantee anything beyond the common understanding 
that the function is undefined, where it is undefined? Except, maybe, 
that such cases must not be handled silently.

The same question applies wrt evaluated predicates.

Is that any clearer? And, if yes, does it make sense? And, if no, at 
what step did I take the wrong turn?


Received on Wednesday, 9 January 2008 12:57:36 UTC

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