- From: Dan Connolly <connolly@w3.org>
- Date: 22 Nov 2002 11:52:43 -0600
- To: Jeremy Carroll <jjc@hpl.hp.com>
- Cc: w3c-rdfcore-wg@w3.org
On Fri, 2002-11-22 at 10:57, Jeremy Carroll wrote: > > > > We can imagine a test case like the xsd:decimal/xsd:integer case, which > instead is an "10"^^xsd:float and "10"^^xsd:decimal. > > I believe that the Schema spec is clear and authoritative on this; even if > the spec's author is not. > > from definition in > > http://www.w3.org/TR/xmlschema-2/#float > > [[ > The basic ·value space· of float consists of the values m × 2^e, where m is > an integer whose absolute value is less than 2^24, and e is an integer > between -149 and 104, inclusive. > ]] > > We set e in this definition to 0, m to the value 10, and we find a value > that corresponds to "10"^^xsd:float. I'm somewhat surprised by this (my impression was that the value space of float was a bunch of open intervals around rationals or something), but after checking a bunch of details, I'm convinced. Please include this in the test stuite. > (Admittedly the L2V mapping is not > clarified in the XML schema recommendation). No? "A literal in the ·lexical space· representing a decimal number d maps to the normalized value in the ·value space· of float that is closest to d in the sense defined by [Clinger, WD (1990)]" > Thus we find that "10"^^xsd:float has 'the value 10 x 2^0'. > I do not think a reading of that phrase as anything other than the > well-known, commonly used, number ten is merited. If the spec had wanted > some strange non-standard representation of values then that should be clear > from text in the spec. > > Similarly, > > the definition of xsd:decimal is: > http://www.w3.org/TR/xmlschema-2/#decimal > and includes > [[ > The ·value space· of decimal is the set of the values i × 10^-n, where i and > n are integers such that n >= 0. > ]] > > Again this has a clear standard meaning, and no indication that any > non-standard reading is required or permitted. > Moreover there is a plausible candidate for the value of "10"^^xsd:decimal > being "the value 10 x 10^-0" (otherwise known as that same number ten). > > (Actually you could chose i=100 and n=1 equally sensibly, and any path that > suggested that the "value 100 x 10^-1" differs from the "value 10 x 10^-0" > seems to lead to madness, [well a very nonstandard view of numbers]). > > Thus, reading the authoritative specs we work out what the values are, and > they are the same. Hence, independent of whether our implementations > actually do it, the relevant entailments are part of RDF datatyping. > > Jeremy -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Friday, 22 November 2002 12:52:45 UTC