Question: Which river on the North American continent has the smallest drainage basin?
Choices: River Thames
Missouri River
Mississippi River
GNU Lesser General Public License
Rhine
Ohio River
Columbia River
Amazon
Hudson River
Danube
SPARQL: SELECT ?e WHERE { ?e <pred:instance_of> ?c . ?c <pred:name> "river" . ?e <continent> ?e_1 . ?e_1 <pred:name> "North America" .  ?e <watershed_area> ?pv . ?pv <pred:value> ?v .  } ORDER BY ?v LIMIT 1
Program:
function: Find
inputs: North America
function: Relate
dependencies: 0
inputs: continent
backward
function: FilterConcept
dependencies: 1
inputs: river
function: SelectAmong
dependencies: 2
inputs: watershed area
smallest
Answer: Hudson River