Here's a relevant link: http://en.wikipedia.org/wiki/Intuitionistic_logic http://en.wikipedia.org/wiki/Intuitionistic_logic Incidentally (a further parallel t

Here's a relevant link: http://en.wikipedia.org/wiki/Intuitionistic_logic http://en.wikipedia.org/wiki/Intuitionistic_logic Incidentally (a further parallel to the Axiom of Choice) Intuitionist Logic is also referred to as Constructive Logic. http://en.wikipedia.org/wiki/Constructivist_mathematics http://en.wikipedia.org/wiki/Constructivist_mathematics One branch of constructivist mathematics eschews the axiom of choice, and all do not allow proof of existence by RAA on non-existence.