W3C home > Mailing lists > Public > public-rif-wg@w3.org > March 2006

RE: An unfortunate side-effect

From: Stan Devitt <stan.devitt@gwi-ag.com>
Date: Fri, 10 Mar 2006 10:46:08 +0100
Message-ID: <1512B5F2ED998C4BB3E2688B8EBEDB79997D5F@mxex-tr-01.gwi-ag.com>
To: 'Michael Kifer' <kifer@cs.sunysb.edu>, Francis McCabe <frankmccabe@mac.com>
Cc: public-rif-wg@w3.org

Note also that this approach has a proven track record.

By way of analogy,  the "content markup" of MathML plays a role similar to
that identified by Michael, while the mathml semantic element provides a
mechanism that allows the authoring system to provide system specific
alternative representations that are regarded by the author as "close

Stan Devitt

-----Original Message-----
From: public-rif-wg-request@w3.org [mailto:public-rif-wg-request@w3.org] On
Behalf Of Michael Kifer
Sent: Thursday, March 09, 2006 10:18 PM
To: Francis McCabe
Cc: public-rif-wg@w3.org
Subject: Re: An unfortunate side-effect 

This is a reasonable thing to do when all else fails. But the goal of many
participants here is to provide greater interoperability for well-known
sublanguages that are already in wide use and for which implementation
techniques are well-known. The roadmap that we presented goes a long way
towards that goal. I admit that the production rule part was fairly weak
there, but I am happy to leave that part to those who care about PRs more.


> I believe that it was Michael Kifer who noted:
> > The implication of this is that RIF will have two completely 
> > disjoint
> > things: declarative rules and production rules, and that we should 
> > probably split into two subgroups.
> I think that this misses the true import of my original comment.
> 1. My *real* issue was with the split between phase I and II; 
> particular wrt the way that PRs were going to be handled.
> 2. If you believe that the kinds of issues with mapping are restricted 
> between the extremes of PRs and predicate logic, then I am afraid you 
> are in for a disappointment. It seems to me that there is at least as 
> much potential for difficulty between different flavors of logic as 
> between logic and PRs. E.g., all the different kinds of approximate 
> reasoning, reasoning over sets of theories, DL versus LP, not to 
> mention all the negative kinds of reasoning :)
> 3. I believe that there is a way of making progress that does not 
> involve YARL (yet another rule language). This is in the area of 
> marking up rule sets in a standardized way without trying to 
> standardize the rule languages themselves.
> As a straw man (YASM) one could imagine something like:
> <ruleset language="prolog" variant="ISO" topic="ancestor">
>    ancestor(X,Y) :- parent(X,Y).
>    ancestor(X,Z) :- parent(X,Y), ancestor(Y,Z).
> </ruleset>
> This would allow meta-tools to process rulesets and decide for 
> themselves whether to handle a given ruleset without trying to 
> actually parse the ruleset first. I think that this could be quite 
> useful in many cases of ruleset integration, but would not address the 
> semantic interoperability issues.
> One might choose to go on to have a standard abstract syntax, with an 
> associated XML concrete syntax, that any rule language could be mapped 
> to:
> <ruleset language="prolog" variant="ISO" topic="ancestor"  
> representation="RIF-XML">
>    <rule>
>      <head>
>        <predication>
>          <predicate name="ancestor"/>
>           etc. etc.
> </ruleset>
> This would have the (perhaps marginal) benefit of allowing 
> standardized processing of the syntax of different rule languages.
> Note that there is not necessarily much implied semantics in this. No 
> discussion about negation etc.
> A third level of defining a meta-notation for semantics, so that we 
> could construct the appropriate interpretation for a ruleset might 
> look like:
> <ruleset language="prolog" ...>
>    <rof>
>      <elimination="resolution"/>
>      <negation="clark"/>
>    </rof>
>    <rule>
>       ...
> </ruleset>
> This last phase, of course, would be the hardest to do. And perhaps 
> have the least payback given any given rule engine is going to have a 
> restricted pre-determined set of rules of inference that it 'knows'
> about.
> Frank
Received on Friday, 10 March 2006 09:46:20 UTC

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