30.0 is the max speed of which ship class?
Entity Entity Entity
m.02kdx9l m.066nrbn m.063z73
E-Class Ultra Panamax Container Ship Fanatic Ultra Boa Type 051B destroyer
class literal
boats.ship_class 30.0^^http://www.w3.org/2001/XMLSchema#float
boats.ship_class type.float
Ship class 30.0
none none
boats.ship_class.max_speed_knots
Max speed
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 :boats.ship_class . 
VALUES ?x1 { "30.0"^^<http://www.w3.org/2001/XMLSchema#float> } 
?x0 :boats.ship_class.max_speed_knots ?x1 . 
FILTER ( ?x0 != ?x1  )
}
}
(AND boats.ship_class (JOIN boats.ship_class.max_speed_knots 30.0^^http://www.w3.org/2001/XMLSchema#float))