Count the number of co-authors that Tsakalidis, A. K. has.
How many co-authors does Athanasios K. Tsakalidis have?
SELECT (COUNT(DISTINCT ?answer) AS ?count) WHERE { ?x <https://dblp.org/rdf/schema#authoredBy> <https://dblp.org/pid/19/5175> . ?x <https://dblp.org/rdf/schema#authoredBy> ?answer FILTER(?answer != <https://dblp.org/pid/19/5175>) }
<https://dblp.org/pid/19/5175>