SPARQL count item in an intersection - sparql

Question

Given the following triples
#prefix ex: <http://example.org/> .
#base <http://example.com/> .
<person1> ex:has_interpretation <interpretation1> .
<interpretation1> ex:refers_to <objectA> ;
ex:resultIn <X> .
<person2> ex:has_interpretation <interpretation2> .
<interpretation2> ex:refers_to <objectA> ;
ex:resultIn <Y> .
<person2> ex:has_interpretation <interpretation3> .
<interpretation3> ex:refers_to <objectB> ;
ex:resultIn <Z> .
<person3> ex:has_interpretation <interpretation4> .
<interpretation3> ex:refers_to <objectA> ;
ex:resultIn <ZZ> .
I am trying to use SPARQL to:
count only the number of object referred to by an interpretation by both person1 and person2 (intersection)
count the number of distinct interpretations over the object
count the number of object not referred to by an interpretation by both person1 and person2
having the above count together with a list of objects referred to by an interpretation and the people who create the interpretation.
I am having trouble specifically with 1 (and consequently, 3), as I cannot find a way to count the intersection of the interpreted objects.
My current SPARQL query which does not obtain what I want:
PREFIX ex: <http://example.org/>
SELECT ?person (COUNT(distinct ?object) as ?c_object) (group_concat(distinct ?interpretation;separator="; ") as ?interpretations)
WHERE {
?person ex:has_interpretation ?interpretation .
?interpretation
ex:refers_to ?object ;
ex:resultIn ?result .
FILTER (?person = <http://example.com/person1> || ?person = <http://example.com/person2> )
}
GROUP BY ?person ?object
What instead I would like is just:
object_uri
number_object
interpretations
person_involved
<objectA>
1
<interpretation1>,<interpretation2>
<person1>,<person2>
Any ideas?

Answer 1

count only the number of object referred to by an interpretation by both person1 and person2 (intersection)
PREFIX ex: <http://example.org/>
SELECT DISTINCT ?obj
WHERE {
<http://example.com/person1> ex:has_interpretation/ex:refers_to ?obj .
<http://example.com/person2> ex:has_interpretation/ex:refers_to ?obj .
}
Here the query matches only those objects (?obj) which have ex:has_interpretation/ex:refers_to paths to them from both <person1> and <person2>.
count the number of distinct interpretations over the object
Just use the COUNT() function as the paths used in the answer for 1. above are distinct (different):
PREFIX ex: <http://example.org/>
SELECT DISTINCT ?obj
WHERE {
<http://example.com/person1> ex:has_interpretation/ex:refers_to ?obj .
<http://example.com/person2> ex:has_interpretation/ex:refers_to ?obj .
}
count the number of object not referred to by an interpretation by both person1 and person2
You might be able to find a fancy way to query for this but I would just count distinct objects:
PREFIX ex: <http://example.org/>
SELECT DISTINCT ?obj
WHERE {
?x ex:refers_to ?obj .
}
...and then subtract the results from 1. above. This is easy to understand and you've already got the results from 1. to work with.