what number of those who are a violist are also a songwriter?
Value
9
class entity
music.songwriter m.012vv0
music.songwriter music.musician_profession
Songwriter Violist
count none
people.person.profession
Profession
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <http://rdf.freebase.com/ns/> 
SELECT (COUNT(?x0) AS ?value) WHERE {
SELECT DISTINCT ?x0  WHERE { 
?x0 :type.object.type :music.songwriter . 
VALUES ?x1 { :m.012vv0 } 
?x0 :people.person.profession ?x1 . 
FILTER ( ?x0 != ?x1  )
}
}
(COUNT (AND music.songwriter (JOIN people.person.profession m.012vv0)))