[Core] Review Core

********* NOTICE **********
My new email address at IBM is: csma@fr.ibm.com
My ILOG email address will not be forwarded after June 8
*****************************

All,

Here are my comments on Core, as promised at the last telecon.

Short story: Core cannot be released as LC without a couple substantial 
changes (most of them correcting inconsistencies, oversights or obvious 
mistakes), but no objection after these changes.

Below, I list, first, the changes that, I believe, are required; then a 
list of additional, editorial comments:

1. Required changes

- section 2.3 (Formulas in RIF-Core), first bullet, "Sub-terms that can 
occur inside atomic formulas can be  either...": add lists to the 
enumeration;

- section 2.3 (Formulas in RIF-Core), second bullet, "Equality terms 
cannot occur...": "Equality and membership terms cannot occur...";

- section 2.5 (Well-formed formulas): the second condition, requiring that 
externally defined predicates and functions always occur with the same 
arity, must be removed (per resolution at telecon March 24, 2009);

- section 3 (RIF-Core semantics): Add a sentence to the effect that 
"RIF-Core is also a syntactic subset of RIF-PRD, and the semantics of 
RIF-Core is identical to th eone of RIF-PRD for that subset";

- section 6.1 (Alphabet of RIF-Core): add "INeg" to the list of excluded 
symbols;

- section 6.4 (Annotations in RIF-Core): In any case, remove the last 
sentence ("...no frame formulas..."), which is wrong. But I would remove 
the previous  sentence as well, since RIF-PRD has the same restrictions as 
RIF-Core in this respect.;

- section 6.6 (Rules and groups): In any case, add the conjunction of 
atoms and/or frames as a possibility for the conclusion;. But I would 
replace the first paragraph with a sentence like: "A RIF-Core rule is a 
well-formed RIF-PRD rule with no nested forall, no binding pattern and 
where the action block is a single atom, a single frame, or a conjunction 
of atoms and/or frames". 

2. Editorial comments:

- Section 1 (Overview): I wonder if, since Import is part of the normative 
syntax and semantics, we should not make it explicit, and stress it, that 
Core includes SWC (and that is true for BLD and PRD as well, of course);

- Beside my usual rant about the presentation syntax (ask anybody who's 
not spend about 4 years bickering about the RIF presentation syntax to 
read the first two sentences of section 2: if they understand that the 
concrete PS is not normative, they must be very clever - well, if they 
understand anything at all, that is :-)...

- Beside my usual rant about the presentation syntax, I said, I suggest 
that section 3 be renamed "RIF-Core as a specialisation of RIF-BLD", and 
that section 6 (RIF-Core as a specialisation of RIF-PRD) be moved next to 
it (that is, to become section 3); 

- I would also move what is currently the first paragraph of section 2 
into the overview (esp. if the section is renamed as suggested);

- talking of section 6 (RIF-Core as a specialisation of RIF-PRD): it might 
be a good idea to point to the section Interoperability in RIF-PRD [1]

- Sub-sections 2.6.1 to 2.6.3 seem very detailled wrt the rest of the 
document, and esp. the normative parts of it. I suggest removing the 
subsections, mentioning only once the EBNF for RIF-Core presentation 
syntax is a specialisation of RIF-BLD presentation syntax, and append the 
three paragraphs about examples 2-4. Btw, the EBNF for the RIF-Core PS is 
also a specialisation of the EBNF for RIF-PRD PS.

Cheers,

Christian

[1] http://www.w3.org/2005/rules/wiki/PRD#sec-interoperability

ILOG, an IBM Company
9 rue de Verdun
94253 - Gentilly cedex - FRANCE
Tel. +33 1 49 08 35 00
Fax +33 1 49 08 35 10


Sauf indication contraire ci-dessus:/ Unless stated otherwise above:
Compagnie IBM France
Siège Social : Tour Descartes, 2, avenue Gambetta, La Défense 5, 92400 
Courbevoie
RCS Nanterre 552 118 465
Forme Sociale : S.A.S.
Capital Social : 609.751.783,30 ?
SIREN/SIRET : 552 118 465 02430