How many {tributary} are for {Arkansas River} ?
Which is the number of the tributaries that Arkansas river have?
How many tributaries does Arkansas River have ?
SELECT ( COUNT ( ?h ) AS ?a ) { resource:Arkansas_River property:tributary ?h }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q8319> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P974> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

SELECT (COUNT(?obj) AS ?value ) { wd:Q8319 wdt:P974 ?obj }
29