Question: List the developers who has contributed to both GNOWSYS and GNU TeXmacs?
SPARQL query: SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/GNOWSYS> <http://dbpedia.org/ontology/developer> ?uri. <http://dbpedia.org/resource/GNU_TeXmacs> <http://dbpedia.org/ontology/developer> ?uri . }
Answer: [GNU] is the developer of both GNOWSYS and GNU TeXmacs.