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Re: ISSUE-126 (Revisit Datatypes): A new proposal for the real <-> float <-> double conundrum

From: Richard H. McCullough <rhm@PioneerCA.com>
Date: Mon, 7 Jul 2008 16:38:57 -0700
Message-ID: <242CBCD68DD74F29B3D1087950AE098E@rhmlaptop>
To: <paul@sparrow-hawk.org>, "Alan Ruttenberg" <alanruttenberg@gmail.com>, "Dave Peterson" <davep@iit.edu>
Cc: "Rob Shearer" <rob.shearer@comlab.ox.ac.uk>, <public-webont-comments@w3.org>, <public-owl-wg@w3.org>, <www-xml-schema-comments@w3.org>

I suggest that you consider following the example of classical mathematical 
analysis -- the delta-epsilon arguments -- or the example of engineering 
approximations.
Domains may be disjoint in theory, but when you make real measurements,
and consider measurement precision/errors, they're not really disjoint.

Dick
----- Original Message ----- 
From: "Dave Peterson" <davep@iit.edu>
To: <paul@sparrow-hawk.org>; "Alan Ruttenberg" <alanruttenberg@gmail.com>
Cc: "Rob Shearer" <rob.shearer@comlab.ox.ac.uk>; 
<public-webont-comments@w3.org>; <public-owl-wg@w3.org>; 
<www-xml-schema-comments@w3.org>
Sent: Monday, July 07, 2008 1:21 PM
Subject: Re: ISSUE-126 (Revisit Datatypes): A new proposal for the real <-> 
float <-> double conundrum


>
> At 10:38 AM -0600 2008-07-07, Paul "Sparrow Hawk" Biron wrote:
>>Alan Ruttenberg wrote:
>>>
>>>I'm sorry for the overgeneralization and didn't mean to insult. It's just 
>>>that as much as I think about it, I can't understand the idea that the 
>>>value space of floats and the value space of decimal are disjoint. 
>>>Fundamentally these represent some of the same real numbers and this 
>>>isn't reflected in the spec. In addition, many numbers that can be 
>>>finitely expressed and be calculated with find no place in *any* of the 
>>>value spaces, e.g. 1/3. It is this sense of "mathematical" that I was 
>>>referring to.
>>
>>The best explanation that I know of was written by Mark Reinhold, a member 
>>of the original schema WG (...and, if memory serves me, was a member of 
>>the team that wrote the Java floating-point spec).
>>
>>During the development of the Schema 1.0 (i.e., a few years before we went 
>>to Rec) we had MANY discussions about the numeric types, and especially 
>>about float and double.  As part of that discussion, Mark wrote a note 
>>entitled "Floating-point datatypes are not real datatypes" [1] that goes 
>>into great detail on this point.  It also serves as a good entry point to 
>>the archives for the discussions the WG had on these issues.
>
> Thanks, Paul, for the history.  That discussion happened during a 9-month
> period when I had to be away from Schema, so I wasn't really aware of it.
>
> Interesting to note that the whole discussion of a parent for decimal,
> float, and double (and even precisionDecimal) was reopened and discussed
> during the early XSD 1.1 development, and again rejected (with and without
> including precisionDecimal).  Apparently for much the same reasons.
> -- 
> Dave Peterson
> SGMLWorks!
>
> davep@iit.edu
>
>
Dick McCullough
http://mKRmKE.org/
Ayn Rand do speak od mKR done;
knowledge := man do identify od existent done;
knowledge haspart proposition list;
mKE do enhance od "Real Intelligence" done;
Received on Monday, 7 July 2008 23:40:27 GMT

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