- From: Michael Smith <msmith@clarkparsia.com>
- Date: Wed, 09 Jul 2008 13:10:47 +0000
- To: Boris Motik <boris.motik@comlab.ox.ac.uk>
- Cc: 'OWL Working Group WG' <public-owl-wg@w3.org>
On Tue, 2008-07-08 at 17:16 +0100, Boris Motik wrote: > - "aaEbb"^^xsd:float - all such constants save for NaN and +-inf are to be interpreted as elements of owl:number I continue to find this problematic, as it ignores the discussion of why floats are not reals (I found [1] quite helpful). Further, I have concern that because the lexical space allows arbitrary precision and due to alternative, inconsistent rounding implementations (permitted by XSD 1.1 [2], see 3.3.5.2) the lexical to value-space mapping could differ between implementations. Thus, two reasoners with xsd conformant lexical to value mapping algorithms could correctly produce different entailments. (I don't have access to IEEE-754 to look into the details here, I'm basing my statements on [2]). > The set of constants is chosen such that implementations don't need to support numbers with arbitrary precision, which might be > quite cumbersome. In fact, implementations are only required to support 32 bit integers and single precision floating point numbers. > There are efficient ways to represent these on virtually all systems. I agree that requiring arbitrary precision for conformance may be placing the bar too high. I note that XSD specifies a number of digits for minimally conformant reasoners [3], [4]. Perhaps we could adopt a similar approach to conformance. -- Mike Smith Clark & Parsia [1] http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/1999Oct/0025.html [2] http://www.w3.org/TR/xmlschema11-2/#float [3] http://www.w3.org/TR/xmlschema-2/#decimal [4] http://www.w3.org/TR/xmlschema11-2/#partial-implementation
Received on Wednesday, 9 July 2008 13:22:49 UTC