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ACTION-420 Review of SW-compatibility

From: Axel Polleres <axel.polleres@deri.org>
Date: Thu, 21 Feb 2008 00:22:00 +0100
Message-ID: <47BCB618.6000408@deri.org>
To: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
Sorry for being late,

SWC review attached.

Probably too late for people to read it before tomorrow, sorry for that, 
didn't finish typing it in earlier. at least before the meeting, most of 
the comments editorial, but some are more fundamental (mybe only a 
matter of explanation by jos) would be good if we could quickly look 
over them.

Axel

-- 
Dr. Axel Polleres
email: axel@polleres.net  url: http://www.polleres.net/

rdf:Resource owl:differentFrom xsd:anyURI .

Review 

RIF SWC


1)

"Web-based languages for the representation and exchange of ontologies (i.e., data models)"
-->
"Web-based languages for the representation and exchange of data and ontologies (i.e., data models)"

2) 
As for the syntaxes, would it make sense to reference (informally) the 
N3/Turtle Submission?
http://www.w3.org/blog/SW/2008/01/15/w3c_team_submission_on_n3_and_turtle

I see that you add a link to N-Triples in Appendix 5 to some testcases document.
Also here, I think the new N3/Turtle document is cleaner and the better reference.

3)
"Another specialization of this use case [...]"

Which use case now? The "this" seems a bit dangling here.

4)
"An RIF rule set which refers to RDF graphs"

should better be:

"An RIF rule set which refers to RDF graphs and RDFS or OWL Ontologies"


5)
"Possible ways to refer to RDF graphs and RDFS/OWL ontologies include annotations in RIF rule sets and extensions of the syntax of RIF."

An alternative could be to refer to RIF Rule Sets from RDF a la using owl:imports in RDF, i.e. the other way around.

6)
"but B can process RIF rules, then the appendix explains how the rule system could be used for processing combinations."

better:

"but B can process RIF rules, then the appendix explains how B's rule system could be used for processing combinations."

7)
"specifies how, in such a combination, the rule set and the graphs interact"

better:

"specifies how rule sets and RDF graphs interact in such a combination "

8)

Table:
"Plain literal without a language tag"
"Plain literal with a language tag"

native speakers? is it normal to use articles here? I would simply say
"Plain literal without language tag"
"Plain literal with language tag"

Likewise "Symbol in a symol space" reads awkward.

9)

"
john brotherOf jack . 
jack parentOf mary . 
"

please use proper N3/Turtle syntax here, e.g.

<john> <brotherOf> <jack> . 
<jack> <parentOf> <mary>. 

or 

@prefix : <http://www.ex.org/>
:john :brotherOf :jack . 
:jack :parentOf :mary . 

same later on in the text and in further examples

10)

Exists ?z ( ?z[rdf:type -> "nameBearer"^^rif:iri] )
Exists ?z ( "http://a"^^rif:iri["http://p"^^rif:iri -> ?z] )

one might find this a bit awkward, that we do not entail actually

Exists ?z ( ?z[rdf:type -> "nameBearer"^^rif:iri]  and  "http://a"^^rif:iri["http://p"^^rif:iri -> ?z] )

here, i.e. we loose co-reference. Do we?

11)
As for the definition of extended RDF graphs.
There are (for many implementers) good reasons, to keep literals and blank nodes
away from the predicate position.

SPARQL, who also slightly extend RDF graphs in the graph patterns, only allow literals 
in subject position in their definition for graph patterns, but don't go as far as we do here:

" Definition: Triple Pattern

A triple pattern is member of the set:
(RDF-T union V) x (I union V) x (RDF-T union V)

This definition of Triple Pattern includes literal subjects. This has been noted by RDF-core.

"[The RDF core Working Group] noted that it is aware of no reason why literals should not
  be subjects and a future WG with a less restrictive charter may
  extend the syntaxes to allow literals as the subjects of statements."

Because RDF graphs may not contain literal subjects, any SPARQL triple pattern with a literal as subject will fail to match on any RDF graph."

I am unsure about whether this liberal definition we use here is a good idea, actually I would like to object against literals in pred positions.
Also, in that sense, the example later on doesn't make sense:

<http://a> <http://p> <http://b> .
<http://a> "http://p"^^rif:iri "http://b"^^rif:iri .
"http://a"^^rif:iri <http://p> "http://b"^^rif:iri .

12)

"The semantics of RIF-RDF combinations is defined through a combination of the two model theories"

better:

"The semantics of RIF-RDF combinations is defined through a combination of the RIF and RDF model theories"


13)

"The RDF Semantics document [ RDF-Semantics ] defines 4 (normative) kinds of interpretations, as well as corresponding notions of satisfiability and entailment:"

better:

"The RDF Semantics document [ RDF-Semantics ] defines 4 (normative) kinds of interpretations, as well as corresponding notions of satisfiability, models, and entailment:"


14)

"This distinction is reflected in the definitions"

better:

"Those four types of interpretations are reflected in the definitions"

15)

"We define the notion of common interpretation, which is an interpretation of an RIF-RDF combination"

better:

"We define the notion of common interpretation, which is the combination of a RIF Semantic structure and a simple RDF (RDF, RDFS, or D, respectively) interpretation for a RIF-RDF combination"

16)
"where s', p', and o' are RIF symbols corresponding to the RDF symbols s, p, and o, respectively. "

shouldn't  we add a "see Table 1" with a link here?

17)

"IR union IP"

better:

"IR &cup; IP"

18)
"Rdf-, rdfs-, "

-->
"RDF-, RDFS-, "
check capitalization in the whole document

19)
In te definition of common interpretations, isn't condition 2 superfluous? (by condition 4.)

20)
"(D intersection (union of all value spaces DS));"

where is DS defined? or do you mean DTS here?

21)
"i.e., a rdfs:subClassOf b is true if a ## b is true."

Why is "if" enough here, and not "iff"? not sure.

22)
What exactly is meant by
"which are used as properties in the RIF domain. "
?

23)
I don't really understand here:

"Note that no correspondences are defined for the mapping of names in RDF which are not symbols of RIF, e.g., ill-typed literals and RDF URI references which are not absolute IRIs."

That means that what is written in the example before breaks:

"
>From this combination we can derive the RIF condition formulas

Exists ?z ( ?z[rdf:type -> "nameBearer"^^rif:iri] )
Exists ?z ( "http://a"^^rif:iri["http://p"^^rif:iri -> ?z] )

as well as the RDF triples

_:y rdf:type nameBearer .
<http://a> <http://p> "a"^^xsd:integer . 

However, "http://a"^^rif:iri["http://p"^^rif:iri -> "a"^^xsd:integer] cannot be derived,
"

By what means is the triple
"<http://a> <http://p> "a"^^xsd:integer . "
derived in this example, if not from the RIF model theory??? 

24)

"RIF-Full"

--> 

"RIF-OWL Full

25)

Definitions in  "3.3.2.1 Modified Semantics for RIF Frame Formulas":

"IT-DL (t [ rdf:type -> A ]) = IR(A)(t) and IT-DL (t1 [ P -> t2 ]) = IR(P)(t1, t2)."

shouldn't that rather be:

"IT-DL (t [ rdf:type -> A ]) = IR(A)(t) and for P != rdf:type IT-DL (t1 [ P -> t2 ]) = IR(P)(t1, t2)."

??

26)
"We say that I DL satisfies a rule Q "

shouldn't that rather be:

"We say that I DL satisfies a DL rule Q "
??? (however, we only define DL rulest, not DL rule before!)

27) 

"It is noted that"
better:
"We remark that"
??

28)

in section 3.3.2.3 in the definition:

"7. ER(u) = set of all tuples ( k, l ) such that IR("u"^^rif:iri)( k, l ) = t (true), for every IRI u in V."

shouldn't this rather be 

"4'. ER(u) = set of all tuples ( k, l ) such that IR("u"^^rif:iri)( k, l ) = t (true), for every IRI u in V."

i.e. this condition replaces condition 4. because it is more general.

29)

There is a dangling

</table>

in section 5.2


That's all!
Received on Wednesday, 20 February 2008 23:22:26 GMT

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