I am using SPARQL Query tab in Protege 5 to query an OWL ontology I have been constructing. I succeded in many kinds of queries, but when I use some specific class of my ontology inside the very same queries (that are apparently well formed) they return no results. Following, two of the problematic queries - assuming "Event" as one of the concepts of the ontology (http://www.semanticweb.org/ontologies/2014/5/MyOnto#Event):
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX onto: <http://www.semanticweb.org/ontologies/2014/5/MyOnto#>
SELECT ?a WHERE { ?a rdfs:subClassOf onto:Event }
and, with the same prefixes
SELECT ?a WHERE { ?a rdfs:range onto:Event }
Both return no results. However, if I substitute "onto:Event" for, let's say, ?b, both return a long list of results - inclunding Event as a match for ?b.
Is it something I'm misusing or forgetting (although I've seen this pattern in several links on internet with people claiming to have got results) or is it a limitation of SPARQL or some issue of the Protege tab?
The problem is that, in fact, although the URI of the ontology is:
<http://www.semanticweb.org/ontologies/2014/5/MyOnto#>
in the OWL document, the prefix used before class names is the IRI:
<http://www.semanticweb.org/ontologies/2014/2/untitled-ontology-662#>
Thus, replacing the old onto: by
PREFIX onto: <http://www.semanticweb.org/ontologies/2014/2/untitled-ontology-662#>
solves the issue.
(Thanks to #Csongor from Protégé Project mail list, who found the answer.)
P.S.: It's also worthy to note that it can't be taken for granted that all the terms in the ontology will be <current_ontology_URI#term> - e.g. if one includes some terms in the ontology and then changes ontology URI, these terms will be identified as <previous_ontology_URI#term> and the new ones as <current_ontology_URI#term> (which was exactly the cause of the problem above).
I had the same problem, whenever using an ontology specific class there were no results although there should have been. My ontology (pizza.owl) was loaded from a local file.
I found that it is required to add the file name in the PREFIX.
PREFIX : <http://www.co-ode.org/ontologies/pizza/pizza.owl#>
After that I got the information that I expected.
Related
I would like to use rules in my ontology so that at the moment of the inference I can retrieve some information not explicitly expressed in the triplestore.
I created a basic ontology and I want to add this rule:
Person(?p) ^ hasSibling(?p, ?s) ^ Man(?s) → hasBrother(?p, ?s)
The SPARQL query I would like to perform is
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX prova: <http://www.example.it/prova/>
SELECT ?subject ?object
WHERE { ?subject prova:hasBrother ?object }
Running this does not return anything. Of course, I have created the individuals for each class, but I have not created the instance that involves hasBrother, as this is what I want the intelligence to retrieve by itself.
So, my question is: is it possible to use SPARQL queries to achieve inference described by rules? Or these kind of inferences are only possible with a dedicated query system? In protegè I learn about the SQWRL tab for instance.
I am using the last version of Protegè (5.5.0) and the last version of the SWRL Rules plugin (2.11). I have defined the rule in the SWRL Tab. Then I tried the SQWRL tab to perform the query, but I get a strange error related to "invalid query name", which I don't really understand. Any suggestion about this second point would be helpful.
How are you?
I 'm taking my first steps with GraphDb and I've found a couple of behaviors that I don't quite understand. Let me build the case.
I have the following Ontology, which I have loaded into GraphDb.
enter image description here
Let's only consider the tree under Persona.
When I go to Visual Graph and type :Persona in the search bar, this is what returns:
enter image description here
As you can see all the nodes corresponding to the ontology are there, but also some other nodes like Class (in different colors), and Thing and Nothing. (Ignore Paul which is an instance I added)
What are these other nodes? and how can I prevent them from appearing in this view?
Now, when I query with SPARQL, and I run
select * where {
?s ?p ?o .
}
If I have "Include inferred data in results" Off, I get this
enter image description here
Which is fine. It's what I would expect.
But ... when I turn inference On , which I believe is one of the true powers of working with rdf, I get around 800 records with all sort of triples with definitions for owl and rdf generic objects.
In order to get only my stuff and keep the inference capability on, I filtered as follows
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX pe: <http://www.semanticlab.com/ontologias/EmpresasYPersonas#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
select * where {
?s ?p ?o .
FILTER (REGEX(str(?s),"Persona*" )).
FILTER (!REGEX(str(?o),"owl*" )).
FILTER (!REGEX(str(?o),"rdf*" )).
}
order by ?s
Which returns
enter image description here
Here I see some inferencing, for example Paul classified as a Persona, which is not explicitly stated.
But on the other hand there are a bunch of new triples that I don't understand nor want, as they don't bring any value: for example the ones with owl:sameAs, owl:equivalentClass, or the ones stating that Persona is a subClassOf Persona (which in fact I believe is wrong).
Could you please explain why this is happening, and how to prevent this behavior?
I'm aware that I might be making some mistakes, so if you spot any, please let me know.
The following SPARQL query
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix skos: <http://www.w3.org/2004/02/skos/core#>
prefix msc: <http://msc.org/resources/MSC/msc2020/>
construct {?s skos:broader msc:00-XX . }
where
{
?s a skos:Concept ; skos:notation ?notation.
filter regex (?notation, "00-\d\d")
}
searches all notations 00-01, 00-02, etc. and constructs a relation to the top level class 00-XX. However, this is only the first of 63 top level classes altogether, so I would like to "loop" over all top level classes automatically. On top, I would like to adapt this to other patterns. Is there a way to do this with SPARQL? If not, what would you recommend instead?
In the meantime we found a solution without SPARQL.
The SPARQL CONSTRUCT query was supposed to create a skos:broader relation between a skos:Concept with a notation like "00-01" (and all other concepts with 00-\d\d notation) and its proper subordinate concept, which for 00-01 is the skos:Concept with the notation 00-XX.
The data originate from a table and Open Refine is much faster in creating the skos:broader statements than using the SPARQL query proposed above and adjusting it to other notation patterns.
We use GREL's value.replace on the cells with the notations to create a new column:
value.replace(/-\d\d/, "-XX").replace(/\d\d>/, "xx>")
The two replacements give us the notation of the original notation's superordinate concept in one step. The second replace already adapts to the other patterns mentioned in the question (e.g. 00A01).
With the original notation and the value in the new column, we can easily create the skos:broader triples by concatenating text and the values from both columns. These can then be exported from OpenRefine and just be copy-pasted to our SKOS vocabulary.
Here is a SPARQL answer based on the query in the question. Using filters and regex (as suggested in the comment by Yahalnaut as a reply to UninforomedUser above) is needed. Creating a skos:broader relation based on two concept's notations requires them to hava an identical sequence of digits before the - . The comparison should only between the first part of the notations, so each 00- should match another 00-but not a 01-. As asked, the solution below only considers topConcepts of the Vocabulary as potential objects for skos:broader. The concepts should also not relate to themselves, therefore the last filter. This should then be adoptable to other patterns as well. Depending on the number of Concepts and the memory available for the query, this may last a while or even stop before finished. It eliminates lot of the effort though.
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix skos: <http://www.w3.org/2004/02/skos/core#>
prefix msc: <http://msc.org/resources/MSC/msc2020/>
construct {?s skos:broader ?y . }
where {
?s a skos:Concept ; skos:notation ?notation.
?y skos:topConceptOf msc: ; skos:notation ?not2.
bind (REPLACE (?not2 , "-XX" , "") as ?1)
bind (REPLACE (?notation , "-\d\d", "" ) as ?2 )
filter (?1 = ?2)
filter (?not2 != ?notation)
}
Let's suppose I have an RDF data about Socrates. The data is shown below
subject, predicate, object
man, being, mortal
Socrates, being, man
To check whether Socrates is mortal I have a request
SELECT *
FROM RDFData t1
JOIN RDFData t2
ON t1.subject = t2.object
Then I have a filter on "Socrates" and "mortal" and if result is not empty, then Socrates is mortal.
It works fine, but my teacher asks to add OWL information.
For example, if we have the next data
subject, predicate, object
man, being, mortal
Socrates, being, Greek
Greek, being, man
My approach does not work, because we have additional step in the chain.
I need to add an OWL static data here and implement a request for arbitrary number of steps in the chain.
What are my next steps?
If we turn your example data into actual RDF (using Turtle syntax), you'd get something like this:
#prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
#prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
#prefix : <http://example.org/> .
:socrates rdf:type :Greek .
:Man rdfs:subClassOf :Mortal .
:Greek rdfs:subClassOf :Man .
If you upload this data into an RDF database (such as RDF4J, Jena, GraphDB, Stardog, Blazegraph, or a host of other options), you can use the following SPARQL query:
ASK WHERE { :socrates rdf:type/rdfs:subClassOf* :Mortal }
This checks if :socrates is of a type that is either :Mortal, or a (direct or indirect) subclass of :Mortal. It returns true if Socrates is a mortal, false otherwise. You don't even need a reasoner for this, you can just use the expressivity of the query language.
If your RDF database supports basic RDFS reasoning, you can simplify your query even further:
ASK WHERE { :socrates rdf:type :Mortal }
I have created object property hasSibling where A hasSibling B, B hasSibling C.I have made this property as transitive and symmetric,
but in inferred instances it is not showing A hasSibling C.
This is showing correctly in protege v4.3 but I am using protege v3.4.8
in my project where i have to use transitive and symmetric object properties.
I have tried Sparql query also but it is showing result for symmetric not for transitive.
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX uni:<http://www.owl-ontologies.com/aa.owl#>
select * where {
?x uni:hasSibling ?y .
}
this is giving result as:
Where in inferred tab nothing came
Kindly suggest how to overcome this problem.
Given the query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX uni:<http://www.owl-ontologies.com/aa.owl#>
select * where {
?x uni:hasSibling ?y .
}
You need to have a reasoning that understands the semantics of the uni:hasSibling relation which is more than likely described in the ontology identified by the URI: http://www.owl-ontologies.com/aa.owl# .
If you were using Virtuoso, this would require the following:
Derive and Inference Rule from
http://www.owl-ontologies.com/aa.owl#
Execute your query with a pragma for invoking the Inference Rule
created in the first step plus another pragma for loading your data
(collection of subject and objects connected by uni:hasSibling
relationship type)
I provide a similar example in my post that demonstrates Reasoning & Inference using British Royal Family relationship types. Also note a recent follow-on post that shows how you can create your own Custom Inference Rules.