Any mapping needs to take into account the specific modeling expression and
what do you actually expect/need to accomplish by using it.
owl:equivalentClass restrictions mostly differ from rdfs:subClassOf
restrictions in that they directly entail additional classification inferences.
For example, let’s say you have:
exPerson a owl:Class;
rdfs:subClassOf [ owl:onProperty ex:parent;
owl:allValuesFrom ex:Person].
ex:Alice a ex:Person;
ex:parent ex:Bob.
We know from this that Bob must be a person.
OWL operates under OWA so not having {ex:Bob a ex:Person} triple will not cause
any validation errors. Instead, it will cause an addition of this triple.
What do you want to happen in SHACL?
If you want to get a validation error to ensure that Bob is a member of the
class ex:Person or one of its subclasses AND not a member of any other class
that does not meet this criteria, you would specify sh:class ex:Person
constraint on ex:parent property in a shape that targets members of ex:Person
class.
If you want to get the inference above, you would specify SHACL rule that
generates the triple for Bob.
If a parent could be a person as well as a member of some other class that is
not a subclass of ex:Person (which is what OWL restriction means), you could
use sh:in constraint with a list of possible classes on the
ex:parent/rdfs:subClassOf*/rdf:type path. This is still not exactly like OWL
since you have to list all possible classes. This is because SHACL operates
under CWA.
Now, let’s say you have:
exPerson a owl:Class;
owl:equivalentClass [ owl:onProperty ex:parent;
owl:allValuesFrom ex:Person].
ex:Alice a ex:Person;
ex:parent ex:Bob.
In this example, there is no additional entailments. The outcome with OWL
reasoning and the possible solution in SHACL will be exactly as with the
rdfs:subClassOf restriction.
Let’s say your data is just:
ex:Alice ex:parent ex:Bob.
Nothing at all will happen.
Let’s say your data is just:
ex:Alice ex:parent ex:Bob.
ex:Bob a ex:Person.
Now, with OWL we would get an inference {ex:Alice a ex:Person}.
To get this inference in SHACL, you would need something like:
ex:PersonRulesShape a sh:NodeShape ;
sh:targetSubjectOf ex:parent ;
sh:rule [
a sh:TripleRule ;
sh:subject sh:this ;
sh:predicate rdf:type ;
sh:object ex:Person ;
] ;
sh:condition ex:HasPersonParentShape. # Rule only applies to subjects of a
triple where objects are persons
ex:HasPersonParentShape a sh:NodeShape;
sh:path ex:parent;
sh:class ex:Person.
If, on the other hand, you want a violation if Bob is a person and Alice is
not, then do the following:
ex:Person a owl:Class, sh:NodeShape;
ex:property [ sh:path ^ex:parent;
sh:class ex:Person].
This is just one type of restriction. Similarly you could consider other types
of restrictions.
For example, what do you expect when they use equivalentClass with
cardinalities and hasValue? This is very tricky since under OWA you would not
get violations for these type of restrictions. For allValuesFrom you could
force violations if you use disjoint classes, but no for these types of
restrictions. Are you using them to only infer class membership? This is also
questionable - OWA does not really produce inferencing for such restrictions
since you never know what is the exact number of values or whether a value
exists or not.
exPerson a owl:Class;
rdfs:subClassOf [ owl:onProperty ex:parent;
owl:cardinality 2].
Let’s say you translate it to SHACL as sh:minCount 2 and sh:maxCount 2
constraint for all people. Note that you would not get a violation with OWL.
Then for
exPerson a owl:Class;
owl:equivalentClass [ owl:onProperty ex:parent;
owl:cardinality 2].
Do you want a rule inferring that anyone with 2 parents is a person? Do you
want a violation if someone has 2 parents and is not a person? Neither of those
would happen in OWL.
> On Apr 14, 2020, at 9:11 AM, 'Bohms, H.M. (Michel)' via TopBraid Suite Users
> <[email protected]> wrote:
>
>
> In our national modelling team the questions were raised how to best map
> owl:equivalentClass to SHACL.
>
> Some ideas:
> 1- related to sh:node (details unclear) (from
> https://spinrdf.org/shacl-and-owl.html
> <https://spinrdf.org/shacl-and-owl.html>)
>
> 2- owl:equivalentClass is just syntactic sugar for:
> -- rdfs:subClassOf in 2 directions
> (ok but how to describe it from one shape-side?)
>
> 3-procedural: shacl-af rule to explicitly code in 2 directions the
> instantiation
>
> An other issue:
> How to deal with more complex variants like:
>
> ex1:Class1 (when property p=p1) equivalent to ex2:ClassY or even:
> ex1:Class1 (when property p=p1) equivalent to ex2:ClassZ (when property q=q1)
>
> we can always fall back to skos:related...but we want to have some more
> semantics.....
>
> thx for advice, Michel
>
>
>
>
> Dr. ir. H.M. (Michel) Böhms
> Senior Data Scientist
>
> T +31888663107
> M +31630381220
> E [email protected] <mailto:[email protected]>
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