Question: What is the official website for the human who is the producer of Niagara Falls (the one whose producer is Hal Roach)?
Choices: http://www.hal-roach.com/
http://www.co.livingston.mi.us
http://www.dakota-fanning.org
http://www.duq.edu
http://www.judaspriest.com
http://www.tfmdistribution.com/lamome/lamome.htm
http://www.co.cambria.pa.us
http://www.city.kyoto.lg.jp/
https://www.apple.com/gr/ios/
http://www.frederikpohl.com/
SPARQL: SELECT DISTINCT ?pv WHERE { ?e <pred:instance_of> ?c . ?c <pred:name> "human" . ?e_1 <producer> ?e . ?e_1 <pred:name> "Niagara Falls" . ?e_1 <producer> ?e_2 . ?e_2 <pred:name> "Hal Roach" .  ?e <official_website> ?pv .  }
Program:
function: Find
inputs: Hal Roach
function: Relate
dependencies: 0
inputs: producer
backward
function: Find
inputs: Niagara Falls
function: And
dependencies: 1
2
function: Relate
dependencies: 3
inputs: producer
forward
function: FilterConcept
dependencies: 4
inputs: human
function: QueryAttr
dependencies: 5
inputs: official website
Answer: http://www.hal-roach.com/