From: Pat Hayes <phayes@ai.uwf.edu>
Date: Fri, 2 Nov 2001 11:14:36 -0600
Message-Id: <p05101012b80883f35842@[65.212.118.166]>
To: Graham Klyne <Graham.Klyne@MIMEsweeper.com>

>At 09:31 AM 11/2/01 +0000, Brian McBride wrote:
>
>>>>Pat's proposal defines a type to be a mapping from a lexical
>>>>space to a value space.  That means that a hexadecimal integer is
>>>>a different type from a decimal integer.
>>>
>>>Obviously the datatype mappings are not the same, but the value
>>>spaces can be overlap or even be the same. We can make them
>>>rdfs:subclasses of one another if you like.
>>
>>
>>Hmmm.  That would make them equivalent.  Its bending my head a
>>little, but they are not equivalent, so that sounds like trouble.
>
>I think there are two uses of "data type" at work here:  Pat's
>document (and also XML schema datatypes, methinks) treats them as a
>lexical space, a value space and a mapping from lexical to value
>space.  The other common use, including typed logics, I understand
>to be set of values that can be denoted by a symbol for a value of
>that type;  i.e. the "value space" only.
>
>I'm guessing that Brian's point is that conflating these ideas in
>RDF might be confusing, or otherwise unhelpful.

Oh, I agree its not helpful to conflate them. But let me probe this
other usage a little. Consider various kinds of numerals, eg decimal,
hexadecimal, octal, binary. Obviously these all have the same value
space, so it doesn't make sense to use something like 'octal number'
to refer to a value space. So I'm left wondering what this usage is
supposed to mean.  For example, what is a decimal *integer* ?

Pat

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Received on Friday, 2 November 2001 12:14:39 UTC

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