[semantics-public] representing DEF/USE information
Jakub Flotyński
flotynski at kti.ue.poznan.pl
Wed Nov 13 05:48:16 PST 2019
I agree that the naming convention reflecting how an element is nested
in the overall scene document (e.g., Viewpoint_2_2_1) can be useful to
rebuild the primary X3D scene from a semantic X3D scene. However, if we
decided to use RDF lists for arrays of values, e.g., coordinates,
colors, translation, size, etc., maybe also element path in the scene
document could be represented by an RDF list? The first number in the
list can indicate the position of the element within its parent element,
the second number - the position of the parent within the grandparent,
and so on. For instance:
instead of:
:Viewpoint_2_2_1 a owl:NamedIndividual, x3do:Viewpoint ; # proposed
we will have:
:Viewpoint_2_2_1 a owl:NamedIndividual, x3do:Viewpoint ; # proposed
x3do:elementPath ( 1 2 2 ) .
Even if the element identifier remains the same, there will be no additional property included in it, as now the path is. Thus, any unique identifier may be assigned to an element without loosing the path. The path to the element within the scene document, which is worth a semantic representation, will have its own property. What do you think?
Best regards
Jakub
W dniu 07.11.2019 o 15:11, Jakub Flotyński pisze:
>
> I agree with the example:
>
> :ViewUpClose a owl:NamedIndividual, x3do:Viewpoint ; # current
>
> x3do:hasParent :Group_2_2 ;
>
> x3do:centerOfRotation "0 -1 0" ;
>
> x3do:description "Hello world!" ;
>
> x3do:position "0 -1 7" .
>
> would become
>
> :Viewpoint_2_2_1 a owl:NamedIndividual, x3do:Viewpoint ; # proposed
>
> owl:sameAs :ViewUpClose ; # DEF
>
> / x3do:hasParent :Group_2_2 ; x3do:centerOfRotation "0 -1 0" ;
> x3do:description "Hello world!" ; x3do:position "0 -1 7" ./
>
> If we have two different individuals in RDF we maintain the relationship to the original X3D document, especially if the naming convention with the numbers (e.g., _2_2_1) is respected. However, for every sameAs individuals, the properties should not be specified again (marked in red italics). Moreover, to reply to one of the questions below - subClassOf cannot be used here instead of sameAs, because subClassOf is for classes, not for individuals.
>
> Best regards
> Jakub
>
> W dniu 07.11.2019 o 14:51, Brutzman, Donald (Don) (CIV) pisze:
>> John, you've identified unfinished business in our design pattern for RDF/OWL representation of an X3D model. Thank you for close review. We never resolved this question.
>>
>> Right now the relationship is only apparent from the names (:MaterialLightBlue and :MaterialLightBlue-USE-1) which are informational for people and not a basis for inference. Am expecting that the provided naming pattern for DEF/USE/other nodes is simply syntactic sugar provided during by X3dToTurtle.xslt conversion, not something we would require in a specification design.
>>
>> Adding "owl:sameAs :MaterialLightBlue ; # USE" to :MaterialLightBlue-USE-1 (as part of X3dToTurtle.xslt conversion) appears to be needed. Or perhaps something else, as considered in our prior emails below.
>>
>> Another omission: not finding the DEF name included in the triples. That is part of the original model and not information that should be lost. Perhaps adding "rdfs:label :MaterialLightBlue ; # DEF" to :MaterialLightBlue is also needed. We should look at other uses of RDF/OWL and see how they handle representations of ID information.
>>
>> Next step: what would relevant questions be regarding DEF and USE nodes be that would utilize this relationship? Perhaps hasDEF hasUSE isUSE properties, or inferences? These can inform writing some queries and seeing if the owl:sameAs relationship works OK. Those steps are still needed.
>>
>> Further consideration and experimentation will be helpful, this information is pretty central and we want to get it right.
>>
>>
>> Relevant triples from HelloWorld.ttl
>> https://www.web3d.org/x3d/content/semantics/examples/HelloWorld.ttl
>> =====================================
>> :Appearance_2_2_2_1_2 a owl:NamedIndividual, x3do:Appearance ;
>> x3do:hasParent :Shape_2_2_2_1 ;
>> x3do:hasMaterial :MaterialLightBlue ;
>> x3do:hasTexture :ImageCloudlessEarth .
>> :MaterialLightBlue a owl:NamedIndividual, x3do:Material ;
>> x3do:hasParent :Appearance_2_2_2_1_2 ;
>> x3do:diffuseColor '0.1 0.5 1' .
>>
>> :Appearance_2_2_3_1_2 a owl:NamedIndividual, x3do:Appearance ;
>> x3do:hasParent :Shape_2_2_3_1 ;
>> x3do:hasMaterial :MaterialLightBlue-USE-1 .
>> :MaterialLightBlue-USE-1 a owl:NamedIndividual, x3do:Material ;
>> x3do:hasParent :Appearance_2_2_3_1_2 .
>> =====================================
>>
>>
>> Relevant specification clause:
>> https://www.w3.org/TR/owl-ref/#sameAs-def
>> =========================================
>> 5.2.1 owl:sameAs
>>
>> The built-in OWL property owl:sameAs links an individual to an individual. Such an owl:sameAs statement indicates that two URI references actually refer to the same thing: the individuals have the same "identity".
>>
>> For individuals such as "people" this notion is relatively easy to understand. For example, we could state that the following two URI references actually refer to the same person:
>>
>> <rdf:Description rdf:about="#William_Jefferson_Clinton">
>> <owl:sameAs rdf:resource="#BillClinton"/>
>> </rdf:Description>
>>
>> The owl:sameAs statements are often used in defining mappings between ontologies. It is unrealistic to assume everybody will use the same name to refer to individuals. That would require some grand design, which is contrary to the spirit of the web.
>>
>> In OWL Full, where a class can be treated as instances of (meta)classes, we can use the owl:sameAs construct to define class equality, thus indicating that two concepts have the same intensional meaning. An example:
>>
>> <owl:Class rdf:ID="FootballTeam">
>> <owl:sameAs rdf:resource="http://sports.org/US#SoccerTeam"/>
>> </owl:Class>
>>
>> One could imagine this axiom to be part of a European sports ontology. The two classes are treated here as individuals, in this case as instances of the class owl:Class. This allows us to state that the class FootballTeam in some European sports ontology denotes the same concept as the class SoccerTeam in some American sports ontology. Note the difference with the statement:
>>
>> <footballTeam owl:equivalentClass us:soccerTeam />
>>
>> which states that the two classes have the same class extension, but are not (necessarily) the same concepts.
>>
>> NOTE: For details of comparison of URI references, see the section on RDF URI references in the RDF Concepts document [RDF Concepts].
>> =========================================
>>
>>
>>
>> On 11/2/2019 7:44 PM, John Carlson wrote:
>>> Aha, ignore previous email, I found this. It would seem if we had multiple sameAs it would be confusing semantically? Not really sure.
>>>
>>> 5. *Improved DEF/USE representation possibilities*
>>>
>>> /Next question/. Wondering: when we define nodes that have a DEF or USE, should we also define owl:sameAs for the regular naming convention of individuals that indicates graph position in the original scene graph?
>>>
>>> For example, current form
>>>
>>> :ViewUpClose a owl:NamedIndividual, x3do:Viewpoint ; # current
>>>
>>> x3do:hasParent :Group_2_2 ;
>>>
>>> x3do:centerOfRotation "0 -1 0" ;
>>>
>>> x3do:description "Hello world!" ;
>>>
>>> x3do:position "0 -1 7" .
>>>
>>> would become
>>>
>>> :Viewpoint_2_2_1 a owl:NamedIndividual, x3do:Viewpoint ; # proposed
>>>
>>> owl:sameAs :ViewUpClose ; # DEF
>>>
>>> x3do:hasParent :Group_2_2 ;
>>>
>>> x3do:centerOfRotation "0 -1 0" ;
>>>
>>> x3do:description "Hello world!" ;
>>>
>>> x3do:position "0 -1 7" .
>>>
>>> Similarly considering USE nodes, we might further elaborate these relationships by describing equivalence of numbered-label with USE name and with original DEF node... Current form:
>>>
>>> :MaterialLightBlue a owl:NamedIndividual, x3do:Material ; # current
>>>
>>> x3do:hasParent :Appearance_2_2_2_1_2 ;
>>>
>>> x3do:diffuseColor "0.1 0.5 1" .
>>>
>>> would become:
>>>
>>> :Material_2_2_3_1_2_1 a owl:NamedIndividual, x3do:Material ; # proposed
>>>
>>> owl:sameAs :MaterialLightBlue ; # USE
>>>
>>> owl:sameAs :MaterialLightBlue-USE-1 ; # USE
>>>
>>> x3do:hasParent :Appearance_2_2_3_1_2 .
>>>
>>> However, if we are going to call them owl:sameAs, they might not be sufficiently distinguished from the original DEF. Perhaps subclassOf is a better relationship?
>>>
>>> Please consider. I will apply next pattern to all examples for further testing.
>> all the best, Don
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