Re: heading toward datatyping telecon

Pat Hayes wrote:
>
> >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

*A* decimal integer is an integer value represented using decimal
encoding ;) But you are right, speaking of "decimal integer" as a value
space does not seem to make sense. However, "decimal integer" makes
sense as a mapping (relationship, property) that associates the strings
complying with the respective ISO 8601 encoding into the value space of
integers.

Sergey