Re: BLD: two issues with the BNF

Axel Polleres wrote:
> 
> Jos de Bruijn wrote:
>> I uncovered two issues with the BNF in BLD.  For me they are not 
>> critical for last call, but for some they might be.
>>
>> The first issue is an error: Profile is not a Unicode string in the 
>> presentation syntax, but it is a term (see section 2.4).
> 
> I do find this critical.
> 
>> The second issue is not an error, but it can be considered misleading 
>> (the BNF is too liberal): in the presentation syntax, rules are 
>> quantified rule implications.  So, an atomic formula is not a rule and 
>> may thus not be directly included in a group.  According to the BNF, 
>> an atomic formula can be considered a rule; this is misleading.
> 
> should be fixed. I think what you say can be easily addressed by
> adding a comment to the EBNF inSection 2.6 which says the following:
> 
> "Note that in this grammar, we allow CLAUSES for rules and ATOMIC 
> formulas as clauses as a shortcut for facts:

I don't really understand what that means.  Either the presentation 
syntax allows atomic formulas inside groups, or it does not.  Currently, 
the presentation syntax (and, consequently, the XML syntax) does not 
allow them, but the grammar (which is a non-normative explanation, not 
definition of the presentation syntax) seems to suggest that they are 
allowed, which is false.
One can then do one of two things: fix the error in the grammar, so that 
it accurately reflects the presentation syntax, or change the 
presentation syntax (and, consequently, the XML syntax) to allow atomic 
formulas inside groups.

Best, Jos

> <ul>
> <li>A CLAUSE rule <i>C</i> is in fact a shortcut for
> <p>Forall <i>vars<sub>C</sub></i> ( <i>C</i> )</p>
> and
> </li>
> <li>An ATOMIC Clause <i>A</i> is in fact a shortcut
> <p> <i>A</i> :- "a" = "a" </p>
> </li>
> </ul>
> "
> 
> We can also write:
>   <i>A</i> :- And()
> 
> for the latter, BTW.
> 
> 
> I would strongly opt for adding this clarification!
> 
> Axel
> 
>> Best, Jos
> 
> 

-- 
                          debruijn@inf.unibz.it

Jos de Bruijn,        http://www.debruijn.net/
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