I just get into knowledge graph/ontology area and have a question for query on it.
Knowledge graph/ontology is built in RDF and query on RDF is done by SPARQL language. For example, "Find all subjects with a given object property"
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX bc: <http://www.base22.com/ontologies/2010/5/bc.owl#>
SELECT ?subject
WHERE { ?subject bc:hasEmployer <http://www.base22.com/ontologies/2010/5/my-contacts.owl#IBM> } LIMIT 100
I suppose in end applications in this example, the user would make the query "Who work at IBM"? How would I convert such a NL query to the SPARQL query?
In Google's knowledge graph query API, it gives one example:
https://kgsearch.googleapis.com/v1/entities:search?query=taylor+swift&key=API_KEY&limit=1&indent=True
This query returns Swift Taylor's detailed information. I am not sure whether Google Knowledge is also stored as RDF triples and therefore needs SPARQL conversion. Plus, it doesn't give examples of how to query on property restrictions(relations), which seems to be more typical types of queries for RDF data.
Generally, how to query on RDF data using natural languages by end users, not system developer?