W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2001

Re: incomplete datatyping (was: Re: datatypes and MT)

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Wed, 07 Nov 2001 10:15:09 +0000
Message-Id: <5.1.0.14.2.20011107100444.03febb90@joy.songbird.com>
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: Sergey Melnik <melnik@db.stanford.edu>, w3c-rdfcore-wg@w3.org
There's a wrinkle here that occurs to me...

At 10:32 PM 11/6/01 -0600, Pat Hayes wrote:
>>_y firstName "Sergey"
>>_y lastName "Melnik"
>>_y monthOfBirth "July"
>>_y dayOfBirth "Tuesday"
>>
>>I'd see that as only meaningful if you also said how to interpret the 
>>literals. So for example I presume it might be kosher to assume
>firstName rdfs:range xsd:string .
>lastName rdfs:range xsd:string .
>but that we might also need something like
>monthOfBirth rdfs:range xxd:EnglishCalendarMonth

[...]

>>You are saying that as long as there is no schema it's a literal value.
>>Once a schema is there, it becomes a data value. To satisfy
>>monotonicity, all data values must then necessarily be literal values,
>>right?
>
>I don't know what a data value is. By literal value I meant the semantic 
>value of the literal, ie the value of the XL mapping applied to the 
>literal. So a literal always denotes the same thing in a given datatype 
>interpretation, but when no schema information is present, there are 
>several alternative such interpretations which satisfy the graph, and it 
>might denote something different in each one.
>
>Nothing *changes* when schema information is added, exactly, but the set 
>of satisfying datatype interpretations is reduced, in the usual way, and 
>that may be enough to fix the interpretation of the literal in all the 
>interpretations that satisfy the graph.

Suppose that in addition to:

   monthOfBirth rdfs:range xxd:EnglishCalendarMonth .

we can also presume:

   monthOfBirth rdfs:range xxd:decimalInteger .

(this being legit RDF) ... might the allow us to write:

   _y monthOfBirth "July" .

OR

   _y monthOfBirth "7" .

?

There are two points I see here:  (a) multiple datatype classes might 
permit ambiguity in the value denoted by a given literal string, and (b) a 
literal value might not have a defined mapping under some presumed datatype 
class.

(a) I see as not really being different from the case where no datatype 
class information is available, except that it seems to run counter to the 
conjunctive nature of type information.

(b) if no mapping is provided by a presumed datatype class, how does this 
affect the truth of the corresponding statement?

#g


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Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
<Graham.Klyne@MIMEsweeper.com>
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Received on Wednesday, 7 November 2001 05:33:03 EST

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