Were M1 , M2 , and M3 directed by a film 's director
SELECT count(*) WHERE {
?x0 ns:film.director.film ?x1 .
?x1 a ns:film.film .
M1 ns:film.film.directed_by ?x0 .
M2 ns:film.film.directed_by ?x0 .
M3 ns:film.film.directed_by ?x0
}