- From: Boris Motik <boris.motik@comlab.ox.ac.uk>
- Date: Wed, 16 Jul 2008 17:52:31 +0100
- To: <public-owl-wg@w3.org>

Hello, As a preparation for today's teleconf, I thought it would be good to summarize the current state of the discussion regarding datatypes in OWL 2. (Of course, this is my understanding, so I apologize in advance if I haven't reflected someone's opinion correctly.) 1. The list of supported datatypes =================================== OWL 2 would support the following datatypes in class restrictions. For each datatype, I specify the space of values that it is interpreted as. 1a. Numeric Datatypes ---------------------- Datatype: owl:numberPlus Value space: The set of all real numbers plus NaN, +inf, -inf, and -0. Facets: minInclusive, minExclusive, maxInclusive, and maxExclusive Note 1: The value +0 is already available in the set of all real numbers. Note 2: This is the base datatype for all other numeric datatypes. Note 3: The facets are inherited by all numeric datatypes and I don't list them separately. Datatype: owl:number Value space: The set of all real numbers (without NaN, +inf, -inf, and -0). Note: The value space is a subset of owl:numberPlus. Datatype: owl:rational Value space: The set of all rational numbers (without NaN, +inf, -inf, and -0). Note: The value space is a subset of owl:number. Datatype: xsd:integer Value space: The set of all integers. The value space is the subset of owl:number. Note: We would also support all the derivatives of xsd:integer, which I won't list separately. Datatype: xsd:float and xsd:double Value space: The set of all real numbers between the minimum and the maximum float or double, plus NaN, +inf, -inf, and -0. Note 1: Thus, the value space is a subset of owl:numberPlus, but not of owl:number (because of the special values). Note 2: The value space is NOT discrete. Datatype: xsd:decimal Value space: The subset of owl:number containing all decimal numbers. 1b. String datatypes --------------------- Datatype: owl:internationalizedString Value space: The set of pairs of the form (string,langTag), where langTag is allowed to be empty. Facets: length, minLength, maxLength, and pattern Note: All facets operate on the string portion of the pair. Datatype: xsd:string Value space: The set of pairs of the form (string,"") (hence, the langTag is the empty string). Note 1: The value space of xsd:string is a subset of owl:internationalizedString. Note 2: OWL 2 would support all string derivatives, which I won't list separately. Note 3: xsd:anyURI is a subset of xsd:string. 1c. Additional datatypes ------------------------- The value space would be disjoint from all other datatypes. Datatype: xsd:boolean Value space: The set { true, false }. Facets: none Datatype: xsd:hexBinary Value space: The set of all finite string of octets (= bytes). Facets: length, minLength, maxLength 1d. Time and date ------------------ I leave these open of the moment, as they might require another round of discussion. 2. The list of supported constants =================================== OWL would support the following constants. * xsd:integer and all its derivatives - A normative implementation would be required only to support constants that fit into 64 bits. * xsd:decimal - A normative implementation would be required only to support constants with 18 decimal digits. This is exactly the same as in XML Schema. * xsd:float and xsd:double - These would allow for NaN, +inf, -inf, and -0. * owl:rational - As per http://www.w3.org/2007/OWL/wiki/OWL_Rational * xsd:string - In RDF and functional-style syntax, constants of the form "string"^^xsd:string can be abbreviated as "string". * owl:internationalizedString - The lexical value of these constants is "string@langTag". The language tag is whatever is behind the last @ sign. - In RDF and functional-style syntax, constants of the form "string@langTag"^^owl:internationalizedString can be abbreviated as "string"@langTag. * xsd:boolean as in XML Schema * xsd:hexBinary as in XML Schema Regards, Boris

Received on Wednesday, 16 July 2008 16:54:11 UTC