What evaluates to false in Ruby?

Question

false and nil evaluate to false in Ruby. Anything else? Please provide links to official/authoritative references.

Answer 1

false and nil are the only ones:

http://www.ruby-doc.org/core-2.1.1/FalseClass.html

Rails provides present? which also includes empty strings and empty arrays: http://api.rubyonrails.org/classes/Object.html#method-i-present-3F