Re: [RIF] What is in the scope of RIF and what is not?

Christian de Sainte Marie wrote:

>I have read in several postings things like "the problem is if the 
>head/conclusion of a rule contains this or that, because it would make 
>the rule unsafe" (e.g. in one of Enrico's mail "the problem happens if 
>the query contains an existential variable (e.g. a bnode), since this 
>would make the rule unsafe"): I do not understand why this is a problem 
>from the view point of the RIF.
>  
>
I agree with Christian. There are many way to make rules that are not 
range-restricted (safe), eg to specify a context in which the rules are 
to be understood. This would be not only a perfectly acceptabvle 
approach on the Web, but also a highly usefull one.

By the way, "range-restricted" has been the first name proposed in a 
publication [1] for what Jeff Ullman later re-named "safe" for, I guess, 
political/visibility reasons. I think, it is good practice in Science to 
acknowledge first contributions by using the corresponding names.

[1] Jean-Marie Nicolas: Logic for Improving Integrity Checking in 
Relational Data Bases. Acta Informatica 18: 227-253 (1982)

>Let me explain: as I understand the use of the RIF, there is a rule 
>language L1 and a rule language L2; somebody writes rules in L1 for a 
>specific purpose and somebody wants to be able to translate those rules 
>into L2 for some specific purpose. In this basic RIF scenario, rules are 
>designed/written in L1, mapped into the RIF, mapped from RIF into L2, 
>and used (e.g. executed by a rule engine, but not necessarily) in L2. 
>And, in this basic scenario, a rule being safe or unsafe is the problem 
>of L1 and L2 and their users and how they use the rules, not the RIF.
>  
>
I agree.

>More generally, my understanding is that the RIF has to be able to carry 
>unambiguously what a rule means, 
>
I would even say: "some of what a rule mean"

>but what an application does, or what 
>it may or may not do with the rule, or the consequences of using that 
>rule, is out of the scope of the RIF.
>  
>
I agree.

As I put it in another email, RIF should be a "lingua franca" not an 
"esperanto".

-- 
Francois

Received on Wednesday, 1 February 2006 08:17:34 UTC