Question: The OS of which software program is a Unix-like operating system?
Choices: Unix
macOS
Android
Mesa
Orange
Brave
Windows 7
Linux
Solaris
Regina
SPARQL: SELECT DISTINCT ?e WHERE { ?e <pred:instance_of> ?c . ?c <pred:name> "software" . ?e <operating_system> ?e_1 . ?e_1 <pred:name> "Unix-like operating system" .   }
Program:
function: Find
inputs: Unix-like operating system
function: Relate
dependencies: 0
inputs: operating system
backward
function: FilterConcept
dependencies: 1
inputs: software
function: What
dependencies: 2
Answer: Regina