what is the video game rating whose rating system includes the content descriptor of horror?
Entity Entity Entity Entity Entity
m.049ybxs m.049ybxz m.049ybxw m.049yby1 m.049yby4
A C B D Z
class class entity
cvg.computer_game_rating cvg.computer_game_rating_system m.049ybzn
cvg.computer_game_rating cvg.computer_game_rating_system cvg.computer_game_content_descriptor
Video Game Rating Video Game Rating System Horror
none none none
cvg.computer_game_rating.rating_system cvg.computer_game_rating_system.content_descriptors
Rating system Content descriptors
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 (?x0 AS ?value) WHERE {
SELECT DISTINCT ?x0  WHERE { 
?x0 :type.object.type :cvg.computer_game_rating . 
?x1 :type.object.type :cvg.computer_game_rating_system . 
VALUES ?x2 { :m.049ybzn } 
?x0 :cvg.computer_game_rating.rating_system ?x1 . 
?x1 :cvg.computer_game_rating_system.content_descriptors ?x2 . 
FILTER ( ?x0 != ?x1 && ?x0 != ?x2 && ?x1 != ?x2  )
}
}
(AND cvg.computer_game_rating (JOIN cvg.computer_game_rating.rating_system (JOIN cvg.computer_game_rating_system.content_descriptors m.049ybzn)))