Re: response to issue pfps-07

From: pat hayes <phayes@ai.uwf.edu>
Subject: response to issue pfps-07
Date: Mon, 3 Feb 2003 17:53:22 -0600

> The rules for typed literals are incomplete.  They do not give a
> meaning for "a"@t^^dt:foo, for dt:foo a datatype and t a language tag.
> 
> -----
> True, and this was a pure editorial slip-up on my part, which others 
> also noted. This will be fixed.
> 
> The proposed form of the datatype semantic conditions are now:
> 1.
> For any typed literal "sss"[@ttt]^^ddd in G, if I(ddd) is in D and 
> 'sss' is a valid lexical form for I(ddd) then IL("sss"[@ttt]^^ddd) = 
> L2V(I(ddd))(sss)
> 2.
> For any typed literal "sss"[@ttt]^^ddd in G, if I(ddd) is in D and 
> 'sss' is not a valid lexical form for I(ddd) then 
> IL("sss"[@ttt]^^ddd) is not in LV
> 
> where the [square brackets] indicate that this part of the literal 
> syntax is optional.

This change means that the language tag is significant for typed literals.

> There is a corresponding (new) inference rule described by the 
> following proposed text added to section 4.3:
> 
> ------
> Since language tags play no role in the meaning of a typed literal, 
> they can in practice be ignored, and any literal of the form 
> "sss"@ttt^^ddd, where ddd is not rdf:XMLLiteral, treated as identical 
> to the same literal without the language tag, "sss"@ddd. 

Incorrect.

> We can 
> capture this convention by special rules which allow language tags to 
> be inserted or removed:
> 
> rdfD 0a
> 
> aaa ppp "sss"@ttt^^ddd .
> =>
> aaa ppp "sss"^^ddd .
> 
> rdfD 0b
> 
> aaa ppp "sss"^^ddd .
> =>
> aaa ppp "sss"@uuu^^ddd .
> 
> Here, ttt and uuu are any legal language tags and ddd is anything 
> other than 'rdf:XMLLiteral'. Clearly, these rules together can 
> replace any language tag by any other.

These rules are not valid with the above semantic change.

> ---
> 
> BTW, for XML literals the conditions (on RDF-interpretations) are:
> 
> if sss is a unicode string which can be parsed into a well-formed XML 
> document, then
> 
> IL("sss"^^rdf:XMLLiteral) is the XML canonical form of the XML 
> document obtained by parsing sss as XML
> 
> and if ttt is a language identifier then

What is a language identifier.  XML defines only language tags.

> IL("sss"@ttt^^rdf:XMLLiteral) is the XML canonical form of the XML document
> <rdf lang="ttt">sss</rdf>

This does not correspond with the treatment in RDF Concepts.

> and otherwise IL("sss"[@ttt]^^rdf:XMLLiteral) is not in LV
> ---
> 
> Pat

peter

Received on Tuesday, 4 February 2003 18:05:42 UTC