Case insensitive URI matching in SPARQL - sparql

Question

I was hoping someone could help me with a SPARQL query I'm writing. I may get some of the terminology wrong, I'm not a SPARQL expert.
I am trying to get some information from the Nobel prizes SPARQL endpoint (data.nobelprize.org/sparql), retrieving the labels of predicates where the labels of objects match a certain string.
So, for example, if I search for an object with an objectLabel that contains the string 'Robert Burns Woodward', I should receive a number of results including:
predicateLabel, objectLabel
"Laureate","Robert Burns Woodward"
"LaureateAward","Chemistry 1965, Robert Burns Woodward"
"AwardFile","Nobel Lecture Robert Burns Woodward"
I have written the SPARQL below which should work, however it does not retrieve any results:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?predicateLabel ?objectLabel
WHERE
{
?subject ?predicate ?object .
?object rdfs:label ?objectLabel .
?predicate rdfs:label ?predicateLabel .
FILTER contains(?objectLabel, 'Robert Burns Woodward')
}
The reason is that the ?predicate URI is in a different case to the URI which is linked to the corresponding rdfs:label property.
So for example, the predicate
http://data.nobelprize.org/terms/nobelPrize
is used to connect laureates to the prizes they have won. Eg:
sub: http://data.nobelprize.org/resource/laureate/231
pred: http://data.nobelprize.org/terms/nobelPrize
obj: http://data.nobelprize.org/resource/nobelprize/Chemistry/1965
However, the rdfs:label is linked to
http://data.nobelprize.org/terms/NobelPrize
not
http://data.nobelprize.org/terms/nobelPrize
Note the difference in case between the two - the second URI has a lower case 'n' in nobelprize, wheras the first uses an upper case N.
So my question is, is there a way in SPARQL to make a URI case insensitive so that http://data.nobelprize.org/terms/NobelPrize will match with http://data.nobelprize.org/terms/nobelPrize? I know it is possible to search for strings that are case insensitive using FILTER regex or FILTER contains, but I don't know if it is possible with URIs.

Answer 1

You're approaching this the wrong way, I think. That data source has two separate concepts. The resource spelled NobelPrize denotes the class of Nobel Prizes, as can be seen in the ontology. The resource spelled nobelPrize is a different resource, namely the relation between a laureate and a particular Nobel Prize.
In other words: they are distinct, deliberately so, and you shouldn't try to turn them into the same thing by doing case-insensitive matches.
It's somewhat odd that that the nobelPrize property has no label in the SPARQL endpoint, because according to the ontology file it should have one. But given that it doesn't have a label, you're sort of stuck with just getting back the predicate URI itself. You can optionally shorten it by snipping of the namespace part using strafter, like so:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT (strafter(str(?predicate), "http://data.nobelprize.org/terms/") as ?predicateLabel) ?objectLabel
WHERE
{
?subject ?predicate ?object .
?object rdfs:label ?objectLabel .
FILTER contains(?objectLabel, 'Robert Burns Woodward')
}
An alternative, which is somewhat more complex but conceptually neater, is that instead of returning the name of the predicate, you return the name of the type of the object to which the predicate points:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?objectClassName ?objectLabel
WHERE
{
?subject ?predicate ?object .
?object a ?objectClass .
?objectClass rdfs:label ?objectClassName .
?object rdfs:label ?objectLabel .
FILTER contains(?objectLabel, 'Robert Burns Woodward')
}