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RE: Things my mother never told me about types and equality...

From: Dare Obasanjo <dareo@microsoft.com>
Date: Thu, 17 Apr 2003 13:26:12 -0700
Message-ID: <B885BEDCB3664E4AB1C72F1D85CB29F805C1F891@RED-MSG-10.redmond.corp.microsoft.com>
To: "Hugh Wallis" <hugh_wallis@hyperion.com>, <xmlschema-dev@w3.org>

Before reading your paper I was wondering, have you paid attention to
the work the XQuery working group has done in this area[0]? 

[0] http://www.w3.org/TR/2002/WD-xquery-20021115/#N40238D

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>  
>  
> -----Original Message-----
> From: Hugh Wallis [mailto:hugh_wallis@hyperion.com] 
> Sent: Thursday, April 17, 2003 1:15 PM
> To: xmlschema-dev@w3.org
> 
> ...or "Q. When is a float not a float? A. When it's a double"
> 
> Doubtless this has been the subject of other discussions 
> before but it has become important for developing the XBRL 
> standard. Because of the way XML Schema has defined its 
> various types it seems it is not possible to use the XML 
> Schema specification directly to compare values of different 
> numeric types for equality even though such a comparison 
> might seem intuitively obvious. (For example I can't see how 
> the XML Schema float 1E0 can be compared against the XML 
> Schema double 1E0). Maybe I am missing something deep in the 
> referenced IEEE spec on this but the link from the XML Schema 
> specification takes me to a table of contents at the IEEE 
> site from which I can get no further. In XBRL, however, it 
> has become essential to know when two items are equal.
> 
> I have prepared the attached discussion paper on which I 
> would be grateful to recive feedback from the XML Schema 
> cognoscenti. You can safely ignore the complications around 
> "precision" and "decimals" that are mentioned but I would 
> really appreciate any comments about the proposed approach. I 
> think that, in a way, it goes some way towards coalescing the 
> disparate numeric XML Schema types. Of course, I may have 
> reinvented the wheel here and, if I have done so, I would 
> appreciate any pointers to other work on the subject since I 
> would far rather reuse existing standards than invent 
> possibly diverging ones.
> 
> I haven't thought this all the way through yet but it seems 
> to me that if we have a properly defined notion of equality 
> between values from different value spaces then we also have 
> an ordering or at least we are very close to one. Any comments anyone?
> 
> Many thanks
> 
> Hugh Wallis
> 
> 
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Received on Thursday, 17 April 2003 16:26:21 GMT

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