From: Jos de Bruijn <debruijn@inf.unibz.it>

Date: Fri, 13 Feb 2009 13:07:31 +0100

Message-ID: <49956283.1090506@inf.unibz.it>

To: RIF WG <public-rif-wg@w3.org>

Date: Fri, 13 Feb 2009 13:07:31 +0100

Message-ID: <49956283.1090506@inf.unibz.it>

To: RIF WG <public-rif-wg@w3.org>

xsd:decimal allows decimals of arbitrary length. However, implementations are only required to support decimals up to a certain length. An implementation may round off a decimal it receives. So, in some implementations 1^^decimal=1.0000000000000000000000000001^^decimal will be always true and in some implementations it will be inconsistent. These two things hamper interoperability and make the semantics of the language unpredictable. I propose to add to conformance that implementations MUST reject RIF documents that contain decimals (or any subtype thereof) bigger than supported by the particular implementation. Yet another problem is that XPath functions and operators states that the if the "number of digits in the result exceeds the number of digits that the implementation supports, the result is truncated or rounded in an implementation-defined manner" [1]. So, in some applications numeric-divide(1^^int,3^^int) returns 0.3333333333333333333^^decimal and in some applications it returns 0.33333333333333333333333333333333333^^decimal At the moment I'm not entirely sure how to solve this. One possibility would be to define entailment relative to some supported subset of decimal. Best, Jos [1] http://www.w3.org/TR/2007/REC-xpath-functions-20070123/#op.numeric -- Jos de Bruijn debruijn@inf.unibz.it +390471016224 http://www.debruijn.net/ ---------------------------------------------- No one who cannot rejoice in the discovery of his own mistakes deserves to be called a scholar. - Donald FosterReceived on Friday, 13 February 2009 12:24:27 UTC

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