Re: Notes on 7/20 BLD draft

Thanks, Harold - some further clarifications below

- Chris

Boley, Harold wrote:
> Chris,
> 
> Thanks for your notes. Michael changed a lot already and will respond
> (perhaps tomorrow, because of CEST timezone). I worked on 2.1.1.3.
> 
> -- Harold
> 
> 
> Note: The section numbers Chris is referring to are generated by
> Sandro's wiki-tr, as used at http://www.w3.org/2005/rules/wg/wiki/Core.
> While the "7/20 BLD" has changed meanwhile, you can always get an
> up-to-date version there.
> 
> 
> 2.1.1.3
> 
> 
>> It would be best if the correspondence between the ASN and the ebnf 
>> were more obvious.  Perhaps this will be generated automatically at 
>> some point, but for now the productions (nonterminals) should have the
> 
>> same names as the classes in the ASN.  I'm happy changing the names of
> 
>> the ASN classes to CONJUNCTION, etc.
> 
> The usual names And/Or are used as visible ASN class names,
> as XML element names, and as EBNF prefix operator names.
> For the EBNF (only) there is a need to distinguish between
> a terminal name like 'And' and an invisible nonterminal name
> like CONJUNCTION that generates an entire expression applying
> the operator to arguments as in 'And' '(' CONDITION* ')'.

Yes - my point is that the nonterminals should have the same names as 
the ASN classes, because I suspect that is what any automatic 
translation would generate - you see what I mean?

Deciding which terminal strings (e.g. "And" but also including things 
like commas, parens, etc) need to be in the concrete ebnf syntax is 
another issue.

>> * It seems to me a cleaner syntax is to remove existentials from 
>> conditions and unify all quantifiers outside the rule (as with 
>> universal now), and add a restriction in horn that existentially 
>> quantified vars cannot appear in the conclusion.
> 
> The RIF Basic Condition Language is meant to be reusable also
> (in PR and) outside the context of any rule, stand-alone (e.g.
> for queries and integrity checking), where existentials cannot
> be rewritten as universals in the Example 3b.->3a. manner.

Oh, you misunderstood - I did not mean eliminate existentials from the 
syntax entirely, I meant move them outside conditions into some sort 
of wrapper or context (like, rules).  This would make, at least, the 
rule syntax cleaner.


-- 
Dr. Christopher A. Welty                    IBM Watson Research Center
+1.914.784.7055                             19 Skyline Dr.
cawelty@gmail.com                           Hawthorne, NY 10532
http://www.research.ibm.com/people/w/welty

Received on Tuesday, 24 July 2007 00:14:20 UTC