Re: Literals: lexical spaces and value spaces

>My particular beef with XML schema datatypes concerns non-integral 
>numbers.  I think the starting point for this value space should be 
>the set of all rational numbers, since any number represented in and 
>manipulated directly by a computer must necessarily be rational 
>(**).  All fixed- and floating-point forms represent rational 
>values.  But (as I recall) XML schema datatypes define non-integral 
>number value spaces based on either fixed-point decimal character 
>representations or IEEE floating point reprersentations.  This means 
>that some simple, everyday values cannot be represented directly 
>using primitive XSD numeric datatypes (e.g. 1/3, or the exact 
>conversion factor for millimetres->inches: 10/254).  This isn't a 
>purely academic argument:  we found rational numbers to be useful in 
>CONNEG work, and they have been defined for CC/PP.
>
>[(**) OK, you could devise exotic schemes where this isn't the case, 
>but for practical purposes I still claim that rational numbers 
>underpin just about all use of numbers in computers.]

Well, pi to you, Sir.

Seriously, I think that while you might be right about all arithmetic 
*computations* in computers, there is still in a descriptive language 
like RDF the possibility of naming, and making assertions about, 
certain irrational numbers. There are lots of mechanical algebraic 
reasoners out there for example which know things like sin(pi/2)=1.

Pat

-- 
---------------------------------------------------------------------
IHMC					(850)434 8903   home
40 South Alcaniz St.			(850)202 4416   office
Pensacola,  FL 32501			(850)202 4440   fax
phayes@ai.uwf.edu 
http://www.coginst.uwf.edu/~phayes

Received on Monday, 5 November 2001 21:31:01 UTC