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FLD review

From: Igor Mozetic <igor.mozetic@ijs.si>
Date: Wed, 13 Feb 2008 12:02:35 +0100
Message-ID: <47B2CE4B.7030008@ijs.si>
To: RIF <public-rif-wg@w3.org>

Overall, I found the RIF-FLD document very well written
and interesting. I think it has the potential to become
a unifying framework for several logic-based languages.
It is not an easy reading, though, and will benefit if we
will be able produce examples, ie, to instantiate the
framework to several dialects. Kudos to the authors!

Regards, Igor


1. Overview

This is a nice and well written introduction.

I would suggest to add a short note at the end of
Syntactic framework about the relation to sorted logics.
It seems that by combining symbol spaces and signatures
(and allowing for explicit representation in the language)
one can easily specify sorts.

In Semantic framework you introduce semantic structures.
I like the term and it seems that it is broader (eg, explicit
parametrization of truths values?) then interpretations 
(as used in LP and DL). Some short note on the distinction 
would be helpful.

In the last paragraph there is a distinction between assumed
set of semantic structures in DL and LP. This is very interesting
and relevant, but I don't grasp it. In LP one deals with Herbrand
interpretations only (corresponding to S), and then shows the 
relation between inference procedure (SLD) and minimal Herbrand model. 
If you could slightly expand and clarify the last sentence it
would be helpful.

XML serialization statement could also be extended to a
paragraph (mentioning classes and roles, XSD and simple
translation between presentation syntax and XML).

2.0.2. Alphabet

I would introduce SlotNames immediately in the first sentence,
along Const and Var (once slotted terms are accepted).

Positional terms. add (eg, t can be a variable) at the end.

2.0.4. Signatures

When you introduce SigNames, they are also disjoint from Const, 
Var, SlotNames. But they are not part of the language, right?
Or you prefer to leave this option open to be able to specify
sorts?

An arrow expression: Signames -> SigNames

2.0.5. Well-formed terms

In the second item in equality, membership and subclass terms:
ti -> t1

2.0.6. Symbol spaces

RIF supports the following symbol spaces...
Do you mean that support for all the subtypes of xsd: string and
xsd:decimal has to be provided by RIF compliant systems?
Shouldn't we make them explicit, then?
Links to XML-SCHEMA2 don't work (temporarily?)

Notes on RIF-compliant support...
A RIF-consuming system
Here it is mentioned what it is _not_ required to support.
What is required?

3.0.1. Semantics

Data types.
A RIF dialect can also introduce new data types it supports.

Logical entailment.
Specifying the set of intended models - I find this a great
idea to parametrize dialect, but some more explanation or
examples would be helpful.

3.0.3. Primitive data types

vale set vs. value space are both used (as synonyms?)

3.0.6. Intended models

p \/ q have two kinds of models -> have two models
Received on Wednesday, 13 February 2008 11:02:56 GMT

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