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Re: The RDF 1.1 Literal Quiz

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 18 May 2011 14:18:07 -0500
Cc: RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <C36C5A5E-C2DF-4BF7-9F31-21780D777E3D@ihmc.us>
To: Richard Cyganiak <richard@cyganiak.de>

On May 18, 2011, at 1:22 PM, Richard Cyganiak wrote:

> The RDF 1.1 Literal Quiz
> ------------------------
> 
> Let's pretend we live in the future and RDF 1.1 has just been published, including this working group's attempt to clean up string literals.
> 
> Now here's a quiz with some RDF trivia questions.
> 
> What are the answers that you'd like to see? Please keep them short -- along the lines of “Yes”, “No”, “Don't care”, “Don't prefer but ok”, “Oh yes please please please”, “WTF!?!?”, “Formal objection!”
> 
> (I tried to phrase the questions in terms of user-visible behaviour and not spec-internal mechanisms. I hope we can get some non-controversial test cases out of this, and pinpoint where we disagree on desired behaviour. If you provide responses, then feel free to add additional questions.)
> 
> 
> 
> Q1. Does this RDF graph (written in Turtle) have one triple?
> 
> <a> <b> 1 .

Not legal RDF syntax, so answer is moot.

> <a> <b> "1"^^xsd:integer .
> 
> Q2. Does this RDF graph (written in Turtle) have one triple?
> 
> <a> <c> "foo" .
> <a> <c> "foo"^^xsd:string .

Don't really care. They are equivalent: whether that is recorded as a syntactic identity or a semantic one seems relatively unimportant. Applications can happily substitute one for the other. 

> 
> Q3. Is this be a valid Turtle file?
> 
> <a> <b> "foo"^^rdf:PlainLiteral .

No.  "foo@"^^rdf:PlainLIteral is barely legal but strongly deprecated in favor of the plain literal syntax.

> 
> Q4. Is a parser allowed to unify "foo" and "foo"^^xsd:string into a single form while parsing?

Yes, I guess. I am happy for parsers to do anything that is valid. 

> 
> Q5. Is this a valid N-Triples file?
> 
> <a> <b> "foo" .

Yes

> 
> Q6. Is this a valid N-Triples file?
> 
> <a> <b> "foo"^^rdf:PlainLiteral .

No, but "foo@" would make it valid (just, see Q3 above)

> 
> Q7. Is this a valid N-Triples file?
> 
> <a> <b> "foo"@en .

Yes
> 
> Q8. Is this a valid N-Triples file?
> 
> <a> <b> "foo"^^xsd:string .

Yes
> 
> Q9. Is this true in SPARQL?
> 
> datatype("foo") == xsd:string

Yes. But if it is true "in SPARQL" then it should be true everywhere, and therefore true in the normative RDF syntax model, to ensure this. 

> 
> Q10. Is this true in SPARQL?
> 
> datatype("foo") == error

No

> 
> Q11. Is this true in SPARQL?
> 
> datatype("foo") == rdf:PlainLiteral

Either way, but SPARQL has spoken on this, so no. 

> 
> Q12. Is this true in SPARQL?
> 
> datatype("foo"@en) == xsd:string

NO. Formal objection. It would follow that _:x owl:sameAs "foo"@en . _:x owl:sameAs "foo"@fr .  was consistent. 

> 
> Q13. Is this true in SPARQL?
> 
> datatype("foo"@en) == error

No. 
> 
> Q14. Is this true in SPARQL?
> 
> datatype("foo"@en) == rdf:PlainLiteral

That would do, though it could be some other datatype, I don't really care as long as there is one.

> 
> Q15. Is this true in SPARQL?
> 
> datatype("foo"@en) == rdflang:en

Weak no. I don't want a different datatype for each possible language tag

> 
> Q16. Does the literal in this RDF/XML fragment have a language tag?
> 
> <rdf:Description rdf:about="a" xml:lang="en">
>   <rdf:b>foo</rdf:b>
> </rdf:Description>

No.
> 
> Q17. Does the literal in this RDF/XML fragment have a language tag?
> 
> <rdf:Description rdf:about="a" xml:lang="en">
>   <rdf:b rdf:datatype="&xsd;string">foo</rdf:b>
> </rdf:Description>

No.
> 
> For each of the following pairs of statements, if the statement on the left is true, then is the statement on the right true as well in a system that supports datatype inference (specifically, {xsd:string}-Entailment)?
> 
> Q18. { <a> <b> "foo" . } => { <a> <b> "foo"^^xsd:string . }	Yes
> 
> Q19. { <a> <b> "foo"^^xsd:string . } => { <a> <b> "foo" . }   	Yes
> 
> Q20. { <a> <b> "foo" . } => { <a> <b> "foo"@en . }		No
> 
> Q21. { <a> <b> "foo"@en . } => { <a> <b> "foo" . }		No
> 
> Q22. { <a> <b> "foo"@en . } => { <a> <b> "foo"@en-GB . }		No. (Getting this right is just too complicated. And for some combinations, it is simply false either way round, eg the Chinese notations.)
> 
> Q23. { <a> <b> "foo"@en-GB . } => { <a> <b> "foo"@en . }		No.
> 
> Q24. { <a> <b> "foo"@fr . } => { <a> <b> "foo"@en . }		NO !!
> 
> 
> 

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Received on Wednesday, 18 May 2011 19:18:37 GMT

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