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Re: Datatype (Map) Conformance Strangeness

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Mon, 13 Apr 2009 15:49:35 +0100
Message-Id: <5824BBF3-8AD4-4292-86C4-465A746071F3@comlab.ox.ac.uk>
Cc: <public-owl-wg@w3.org>
To: Michael Schneider <schneid@fzi.de>
I agree with Peter that this is a technical document and not one that  
I would expect any "user" to be interested in -- it is mainly  
targeted at implementers of OWL tools who should, I assume, be  
familiar with terms such as datatype map. So, I don't see mentioning  
datatype maps here to be inherently problematical.

Currently, conformance is the *only* place that specifies what the  
datatype map has to be when the direct semantics is applied. We can  
argue about the wisdom of this, but I suggest not to try to change it  
before LC as there is too much danger that we will just mess things  
up -- we could always re-organise things later as the change would  
only be editorial. This being the case, we can't eliminate mention of  
datatype maps from Conformance. I left this statement mentioning both  
the OWL Datatype map and the OWL 2 Full Datatype Map as it would look  
strangely asymmetrical otherwise, and I don't believe that this  
statement is actually wrong (even if it is redundant).

However, it is certainly the case that the note about the datatypes  
that can occur in conformant OWL DL documents is in the wrong place  
and should *not* refer to datatype maps but rather to the set of  
datatypes listed in Section 4 of SS&FS (plus rdfs:Literal). I have  
therefore moved this note into the Document Conformance section.

It is also the case that having Datatype Conformance be a subsection  
of Document conformance is wrong, as the former talks about semantic  
conditions and the latter about syntactic ones. I therefore promoted  
Datatype conformance into its own subsection.

I think that the  above mentioned changes are sufficient for the time  
being -- as I said above, we can think some more about the  
organisation of these various documents after LC.

Ian


On 12 Apr 2009, at 08:46, Michael Schneider wrote:

> Hi Ian!
>
> I argued for not talking about "datatype maps" in the Conformance  
> document
> at all. I suggest to just talk about "(sets of) datatypes". My  
> proposed
> revision of the section in my previous mail reflects this.
>
> I don't see why referring to datatype maps would be necessary or would
> provide any relevant additional information. We will just open the
> Conformance document up to unnecessary criticism.
>
> I consider datatype maps as an internal aspect of the Direct  
> Semantics and
> the RDF-Based Semantics. So let's talk about datatype maps  
> exclusively in
> the semantics documents. I think it would even be best to not talk  
> about
> datatype maps in the Structural Spec, but, again, only about (sets of)
> datatypes.
>
> Michael
>
>> -----Original Message-----
>> From: Ian Horrocks [mailto:ian.horrocks@comlab.ox.ac.uk]
>> Sent: Saturday, April 11, 2009 12:42 AM
>> To: Michael Schneider
>> Cc: public-owl-wg@w3.org
>> Subject: Re: Datatype (Map) Conformance Strangeness
>>
>> I agree with you that this has got rather confused. I think that the
>> problem is twofold:
>>
>> 1) I added the (redundant) note about conformant ontology documents
>> in the wrong place -- this could actually be part of the definition
>> of an OWL 2 DL ontology document (it is redundant because the
>> condition is already one of the conditions that an ontology must
>> satisfy in order to be an OWL 2 ontology as specified in Section 3 of
>> SS&FS).
>>
>> 2) Section 2.1.2 is talking about semantic conditions, yet it is in
>> the "Document Conformance section.
>>
>> Thus, I think that the correct way to fix the problem is:
>>
>> 1) Move the note on datatypes to be part of the definition of an OWL
>> 2 DL ontology document (or get rid of it altogether).
>>
>> 2) Promote 2.1.2 to (sub) section 2.2 (Tool Conformance will then
>> become Section 2.3).
>>
>> I also think that the text should be changed slightly to say:
>>
>> "In OWL 2, semantic conditions are defined with respect to a datatype
>> map. This MUST be either the OWL 2 datatype map (as defined in
>> Section 4 of the OWL 2 Syntax specification [OWL 2 Specification]),
>> an OWL 2 RDF-Based datatype map (as defined in Section 4.1 of the OWL
>> 2 RDF-Based Semantics [OWL 2 RDF-Based Semantics]), or an extension
>> of the OWL 2 datatype map to include additional datatypes.
>>
>> OWL 2 Profiles may support only a reduced set of datatypes. This is,
>> however, a syntactic condition that must be met by documents in order
>> to fall within the relevant profile, and the semantic conditions on
>> the supported datatypes are unchanged, i.e., they are still defined
>> by an OWL 2 RDF-Based datatype map or a (possibly extended) OWL 2
>> datatype map. These datatype maps define semantic conditions on
>> unsupported datatypes, but as these datatypes never occur in
>> conforming documents the additional conditions are simply  
>> irrelevant."
>>
>> I assume that it is correct to say that semantic conditions may be
>> defined by an OWL 2 RDF-Based datatype map -- presumably tools using
>> the RDF-Based semantics will use such a datatype map.
>>
>> Ian
>>
>>
>>
>> On 10 Apr 2009, at 16:19, Michael Schneider wrote:
>>
>>> Hi!
>>>
>>> I had a closer look at the "Datatype map conformance" section
>>> (§2.1.2) in the Conformance document:
>>>
>>>   <http://www.w3.org/2007/OWL/wiki/index.php?
>>> title=Conformance&oldid=21801#Datatype_Map_Conformance>
>>>
>>> I am pretty confused by the current state. I don't understand why
>>> the section refers to the OWL 2 Full datatype map, or to datatype
>>> maps at all? The section is still about syntactic conformance, and
>>> the only relevant thing here seems to be which datatypes may occur
>>> in ontologies.
>>>
>>> I think, the paragraph confuses two things:
>>>
>>> 1) The set of datatypes and their properties, i.e. value spaces,
>>> lexical spaces, facets. These are specified in the Structural Spec
>>> (mainly by referring to XSD and other specifications) and are
>>> invariant for the Direct Semantics and the RDF-Based Semantics.
>>>
>>> 2) The definitions of datatype maps. These definitions are part of
>>> the two semantics, and they differ from each other structurally in
>>> order to match the different semantic frameworks.
>>>
>>> I believe only 1) is relevant for Section 2.1.2, while the
>>> (different) aspects of datatype maps in 2) have no relevance for
>>> syntactic conformance at all.
>>>
>>> Maybe the confusion already stems from the title that has been
>>> chosen for this section (and has been around for a while, I think):
>>> I'd say that it should be changed from "Datatype Map Conformance"
>>> to "Datatype Conformance", because datatype /maps/ do not really
>>> play a role here, only the /set/ of datatypes supported by OWL 2 is
>>> of relevance.
>>>
>>> Here is a proposal for a revision of the Section as I think it
>>> would be more appropriate:
>>>
>>>>>>>>>>>> BEGIN PROPOSAL <<<<<<<<<<<<<<<
>>>
>>> ==== Datatype Conformance ====
>>>
>>> In OWL 2, semantic conditions are defined with respect to a set of
>>> datatypes. This <em title="MUST in RFC 2119 context"
>>> class="RFC2119">MUST</em> be either the set of datatypes as defined
>>> in [[Syntax#Datatype_Maps|Section 4]] of the OWL 2 Syntax
>>> specification [<cite>[[#ref-owl-2-specification|OWL 2
>>> Specification]]</cite>]), or an extension of this set to include
>>> additional datatypes.
>>>
>>> Note that:
>>> # A conformant OWL 2 DL ontology document <em title="MUST NOT in
>>> RFC 2119 context" class="RFC2119">MUST NOT</em> use datatypes other
>>> than those specified in [[Syntax#Datatype_Maps|Section 4]] of the
>>> OWL 2 Syntax specification [<cite>[[#ref-owl-2-specification|OWL 2
>>> Specification]]</cite>].
>>> # OWL 2 Profiles may support only a reduced set of datatypes. This
>>> is, however, a syntactic condition that must be met by documents in
>>> order to fall within the relevant profile, and the semantic
>>> conditions on the supported datatypes are unchanged. This also
>>> defines conditions on unsupported datatypes, but as these datatypes
>>> never occur in conforming documents the additional conditions are
>>> simply irrelevant.
>>>
>>>>>>>>>>>> END OF PROPOSAL <<<<<<<<<<<<<<<<<
>>>
>>> Cheers,
>>> Michael
>
> --
> Dipl.-Inform. Michael Schneider
> Research Scientist, Dept. Information Process Engineering (IPE)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
> WWW  : http://www.fzi.de/michael.schneider
> ====================================================================== 
> =
> FZI Forschungszentrum Informatik an der Universität Karlsruhe
> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
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> Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael  
> Flor,
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>
Received on Monday, 13 April 2009 14:50:13 GMT

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