Print

Print


It is fairly simple to provide a semantics for OWL that allow for failure
to prove that something is true to be grounds  for inferring that it is
false.

This kind of semantics is commonly referred to as Negation As/By Failure
(NAF).

One widely available reasoner that supports this kind of semantics is TrOWL
<http://trowl.eu> -
see <
http://trowl.eu/documentation/using-local-closed-world-reasoning-in-trowl/>

A commercial system that use OWL with NAF semantics for validation is
stardog,  which is a SPARQL database from Clark & Parsia -
http://docs.stardog.com/icv/

Cyc supports the assertion of completeness (either that the the complete
extent of a predicate is inferable , or more strongly, that the complete
extent has been asserted.  This completeness information can be used as an
argument against something, which can be used to reach a definitive
conclusion if NAF is enabled when inferencing.

It is also possible to explicitly close the world by  asserting
disjointUnion axioms before validation, but direct support is better.

Simon
Another bit of information for anyone interested: The BIBFRAME profiles
follow the Description Set Profile developed by the Dublin Core Community
in 2008 [1]. The latter continues to be a working draft, and therefore
doesn't have final status. Notably, the DSP was developed as a design for
an XML schema. (And an XSD was created but apparently never tested.) The
DSP essentially provides a record structure that can be applied to RDF
data. It includes a top "description template" that then contains (in an
XML hierarchical sense) descriptions (generally of entities); descriptions
in turn define the statements or elements that will describe the entities.

I looked again at the DSP and indeed it does not define an identifier for
statement descriptions, similar to the lack of an identifier for the
BIBFRAME property template. This is viable in an XML structure, although I
personally would opt to provide an identifier for the set of constraints
that relate to the property, even in an XML structure. In fact, in the
pseudo-code examples that I created for the DC guidelines document for
Application Profiles [2], I did include such an identifier. Outside of the
structure confines of XML, the lack of an identifier may not be viable.

One question that the Dublin Core RDF AP group [3] will investigate is
whether a one can define a Profile using RDF, or if, because of the
semantics of RDF, validation must take place outside of the RDF
definitions. Shape Expressions[3] (soon to be known as Data Shapes) uses
something resembling RegEx, and SPIN[4] is based on SPARQL, which is a
query language. These latter two are taking place within the W3C community,
and the Dublin Core work will coordinate with them. The variety of
approaches, to me, is evidence of the difficulty of effecting common data
processing validation on the semantics of RDF, but it is also evident that
there is a growing need to find a solution.

kc

[1] http://dublincore.org/documents/dc-dsp/
[2] http://dublincore.org/documents/profile-guidelines/
[3] http://wiki.dublincore.org/index.php/RDF-Application-Profiles
[4] http://www.w3.org/2013/ShEx/Primer
[5] http://www.w3.org/Submission/2011/SUBM-spin-modeling-20110222/

On 7/1/14, 8:38 AM, Karen Coyle wrote:

> Could I bring up another question? I note that the property template uses
> the property URI as its identifier. I believe that this may be problematic,
> as the property URI is then identifying two different things: a property,
> and a graph that exists in a particular profile context. This could cause
> confusion in an environment where a single property may be used in more
> than one profile with different attributes.
>
> As an example, I could have two profiles, one of which has bf:title as
> mandatory, the other does not. As there are no "records" in RDF, my set of
> triples would have:
>
> <bf:title><bf:Mandatory>"true"
> <bf:title><bf:Mandatory>"false"
>
> A resource template would include <bf:title> in its array of property
> templates. Therefore, wouldn't bf:title be both true and false whenever it
> is used in a profile?
>
> Thanks,
> kc
>
>
> On 7/1/14, 2:07 AM, Svensson, Lars wrote:
>
>> Dear Kevin,
>>
>> Late thanks for your comments and clarifications. My comments inline:
>>
>>  First of all thank you for your work on the BIBFRAME Profiles. I think
>>>> the
>>>> notion of profiles will be increasingly important in the library
>>>> community,
>>>>
>>> and
>>>
>>>> perhaps particularly for an exchange format like BIBFRAME that is not
>>>> tied
>>>>
>>> to
>>>
>>>> a specific cataloguing code. I see some overlap with the work being done
>>>>
>>> on
>>>
>>>> RDF application profiles so I copy the DCMI Architecture List.
>>>>
>>>> Having studied the document on BIBFRAME Profiles [1] I have some
>>>> questions and hope that someone can shed some light here.
>>>>
>>>> §2.2 Resource Template
>>>> How do the resourceURI and the resourceLabel relate to each other? My
>>>>
>>> first
>>>
>>>> understanding was that the resourceLabel is the label of the resource
>>>> available at the resourceURI (and thus available by dereferencing the
>>>> resourceURI). In the example (Fig 2.2a), however, there is the
>>>>
>>> resourceLabel
>>>
>>>> Book” and the resourceURI http://bibframe.org/vocab/Text (which is not
>>>> a
>>>> book). Can you please expand a bit on this in the document?
>>>>
>>>
>>> -- When Bibframe Profiles are used as cataloging templates, which is how
>>> they are used presently but with additional future uses to be considered
>>> (there has been some "validation" talk, but very little and very
>>> inconclusive),
>>> it is possible to alter the "labels" of classes/resources and properties
>>> for
>>> specific user communities.   For example, with a Bibframe Profile, you
>>> could
>>> use the label "Number of pages" with the property bf:extent, which, in
>>> the
>>> vocabulary, has a "Extent" as its label.  For the specific community
>>> cataloging
>>> a book, "Number of pages" is more descriptive about what is expected to
>>> be
>>> entered into the field versus "Extent."  So, in the example above,
>>> "bf:Text,"
>>> which has a label of "Text" in the vocabulary, would display to the user
>>> as
>>> "Book" in the editor, where Bibframe Profiles act as cataloging
>>> templates.
>>> Does this help clarify the idea a little?
>>>
>> Yes, it does. If the resource label is mainly for UI purposes, perhaps it
>> could be a solution to change "resourceLabel" to "uiLabel" or something
>> similar.
>>   [...]
>>
>>  §2.5 Value datatype
>>>> Is there a reason not to use the XML schema datatypes, where applicable,
>>>> and to define RDF/OWL datatypes (subclass of rdfs:Datatype and OWL
>>>> Restrictions) when you need new ones? In Figure 2.5, you could just
>>>>
>>> specify
>>>
>>>> xsd:date.
>>>>
>>> -- Actually, "defaultURI" could be
>>> "http://www.w3.org/1999/XMLSchemadate" if you wanted it to be.  "xsd" is
>>> just a namespace prefix after all.   Anyways, Eric and all could provide
>>> more
>>> details about what was intended but the text indicates that the ISO8601
>>> date
>>> would be "a variation on the ISO 8601 date standard," which is why, I
>>> presume, xsd:date was not used.
>>>
>> OK. For interoperability, pre-defined datatypes should of course be
>> preferred. Could you add such a recommendation to the document?
>>
>>  §4 Serialisation
>>>> Is there a reason to restrict the available serialisations? In general
>>>> you could
>>>> say that any existing (RDFXML, Turtle, N-Triples, JSON-LD, …) or future
>>>> RDF
>>>> serialization is acceptable in BIBFRAME? And yes, examples please in
>>>> Turtle.
>>>>
>>> -- Just to be clear: Serialization here refers to serialization of a
>>> Bibframe
>>> Profile, not Bibframe resource data itself.  Correct, if Bibframe
>>> Profiles were
>>> expressed inTurtle then presumably any RDF serialization would also be
>>> viable.  Personally, I think pushing the Profile spec into Turtle would
>>> result in
>>> some unwieldy RDF, but I'd have to see it to know.
>>>
>> OK, we should try and see what happens...
>>
>>  §6.1 Default BIBFRAME Profile
>>>> Here I don’t understand what you mean by saying “Human readable labels
>>>> for the display are extracted from the RDF schema associated with the
>>>> class
>>>> identifiers”. Which “class identifiers” do you refer to? And: If you can
>>>>
>>> extract
>>>
>>>> the label by dereferencing a URI, why repeat it in the profile?
>>>>
>>> -- The answer here is more or less the same as given in response to your
>>> comment about section 2.2 above.
>>>
>> OK.
>>
>>  The "class identifiers" are the
>>> resourceURIs and propertyURIs, which refer to classes and properties
>>> defined in the Bibframe vocabulary.  We can probably come up with a
>>> better
>>> way to refer to these instead of using "class identifiers," which is to
>>> say that I
>>> see the confusion.  The "human readable labels" are the values you see in
>>> that example associated with the resourceLabel and propertyLabel
>>> properties.  Looking at the example, however, "resourceLabel: Book"
>>> should
>>> really be resourceLabel: Text."  The idea was to use the same labels in
>>> the
>>> profile as used in the vocabulary, but - as with my comment above - it
>>> is a
>>> profile creator's choice to use whichever label he or she wants to use
>>> for a
>>> resource or property in a Profile.  For example, since the "author"
>>> property is
>>> repeatable, the Profile label could be "Author(s)" instead of the
>>> singular
>>> "Author," which /is/ the property's actual label, so that the cataloger
>>> would
>>> know more than one is permissible.  It’s a feature.
>>>
>> OK, got it. And I admit that I cannot come up with something better than
>> "class identifiers". We'd have to work on that.
>>
>>  In the example you use the domain name “examplelib.org”. In order to
>>>>
>>> make
>>>
>>>> sure that you do not (by accident) use a domain name actually used by
>>>> someone, it would be better to use the domains example.com or
>>>> example.org or their subdomains, e. g. library.example.org.
>>>>
>>> -- OK, but can we agree this is a pretty minor point?  :) It's used
>>> twice, both as
>>> part of a dummy email address within a note field, not as part of a
>>> resource/property URI.
>>>
>> Yes, it's a minor point, but it's helpful since it shows (at least
>> technically savvy readers) that it's really just an example and doesn't
>> refer to any existing data.
>>
>>  §6.2 RDA as a BIBFRAME Profile
>>>> Shouldn’t the frbr:Item map to bf:HeldItem instead of to bf:Instance?
>>>>
>>> -- Yes, we'll have to get the graphic updated.
>>>
>> OK.
>>
>> Best,
>>
>> Lars
>>
>>
>
-- 
Karen Coyle
[log in to unmask] http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet