Re: varieties of datatyped tagged literals

On 9 Sep 2011, at 02:51, Pat Hayes wrote:
>> The *literal* has a lexical form.
>> 
>> The *datatype's* lexical space is empty.
>> 
>> Consider "hello"^^xsd:integer. That's a typed literal and it has a lexical form "hello". That lexical form is not in the lexical space of the literal's datatype.
> 
> So the literal is ill-typed. One cannot have a well-typed literal with a lexical form when the datatype has an empty lexical space. Yet there are, apparently, well-typed literals with this type, and (you tell me) they have a lexical form. Which ought to be impossible.

The notion of ill-typedness does only apply to literals whose value is determined using an L2V mapping. The value of a language-tagged string literal is defined directly as <lexicalForm,languageTag>, so the notion of ill-typedness does not apply.

>> “lexical form” and “lexical space” are two separate concepts in RDF, and have always been. There's nothing new here.
> 
> Of course they are different concpets. One is the set of all the others.

That's nonsense. "hello" is the lexical form of the typed literal "hello"^^xsd:integer. Nevertheless, "hello" is not in the lexical space of the datatype denoted by xsd:integer.

The lexical form of a literal can be *any* string. It doesn't imply membership in some datatype's lexical space.

> But you want this set to be empty, but to also have members.

No, I do not want this set to have members and I never said so.

[[
The abstract syntax has a lexical form and language tag (like in RDF 2004). The value is assigned directly (like in RDF 2004), bypassing the datatype. The datatype has an empty lexical space and empty L2V mapping.
]]

The language-tagged string *literal* has a lexical form. The *datatype* has an empty lexical space. The datatype exists merely so that RDF Semantics gets a pre-populated value space and doesn't have to do any extra dance to make the datatype-as-classes logic work for rdf:langString.

Best,
Richard

Received on Friday, 9 September 2011 04:51:28 UTC