RE: [TED] CORE Pages on Positive Conditions and Horn Rules Edited: Slots & Constraints

Thanks for your questions.

Background for this response is Hassan's CLP formulation:
http://www.w3.org/2005/rules/wg/wiki/B.1.1_CLP_Formulation

Slide 3 from the breakout and the plenary makes two
related distinctions, which should have been separated
more clearly, as done below.


Positional vs. slotted arguments
(already in RIFRAF):

Positional arguments: f(A1, ..., An)

Slotted arguments: f{k1->A1, ..., kn->An}

Remark: f(A1, ..., An) viewable as shorthand for f{1->A1, ..., n->An}


Herbrand unification assumed vs. equational constraints explicated
(suggestion for RIFRAF):

Herbrand unification assumed:

f(a1, ..., an) is unified with f(A1, ..., An)
by dynamically solving a1=A1, ..., an=An

f{k1->a1, ..., kn->an} is unified with f{k1->A1, ..., kn->An}
by dynamically solving a1=A1, ..., an=An

Equational constraints explicated:

f(a1, ..., an) is statically transformed,
via abstraction f(?x1, ..., ?xn), i.e. f{1->?x1, ..., n->?xn},
to a conjunctive constraint call
(?x1=) f.1=a1, ..., (?xn=) f.n=an

f{k1->a1, ..., kn->an} is statically transformed,
via abstraction f{k1->?x1, ..., kn->?xn},
to a conjunctive constraint call
(?x1=) f.k1=a1, ..., (?xn=) f.kn=an


I'm traveling, but will come back to email later.

-- Harold


-----Original Message-----
From: Dave Reynolds [mailto:der@hplb.hpl.hp.com] 
Sent: Sunday, November 19, 2006 11:16 AM
To: Boley, Harold
Cc: RIF WG
Subject: Re: [TED] CORE Pages on Positive Conditions and Horn Rules
Edited: Slots & Constraints

Boley, Harold wrote:
> Referring to the slides of an F2F4 breakout session
> (http://lists.w3.org/Archives/Public/public-rif-wg/2006Nov/0025.html),
> I edited two wiki pages for extending the existing work with
> slots and calls to external constraint solvers (ACTION-180):

Thanks. I'm not sure I properly understood the results from the breakout

session so forgive me if these questions are off base ...

> Slots (CORE Page on Positive Conditions):
> 
> http://www.w3.org/2005/rules/wg/wiki/A.1_Basis%3A_Positive_Conditions
> 
>
http://www.w3.org/2005/rules/wg/wiki/A.1_Basis%3A_Positive_Conditions?ac
> tion=diff&rev2=45&rev1=43

That just seems to add slotted notation in as an additional piece of 
syntax. For some reason I'd had the impression that the proposal was 
that the slotted notation would be the fundamental one with labels '1', 
'2' etc used to translate positional notation. I guess I expected the 
revised abstract syntax to only have slotted notation and there would be

a separate "with syntactic sugar" syntax layered on top.

Note, it's not that I'm necessarily trying to push for this just trying 
to understand at this stage.

> Calls to external constraint solvers (CORE Page on Horn Rules):
> 
> http://www.w3.org/2005/rules/wg/wiki/B.1_Horn_Rules
> 
>
http://www.w3.org/2005/rules/wg/wiki/B.1_Horn_Rules?action=diff&rev2=24&
> rev1=22

First, I guess I have the same question as above. This seems to have 
EXTCALL added as an optional extra call whereas I thought the proposed 
most primitive form of RIF Core was slotted notation with a conjunction 
of ground dot-notation terms in the constraint equation.

Second, and related, presumably there needs to be an abstract syntax for

the primitive constraint equations needed for Herbrand terms?

Dave

Received on Tuesday, 21 November 2006 02:01:33 UTC