What would happen if this question was reformalated as "If there was another civilization, would they have invented lambda calculus?"
As for the question of "is mathmatics discovered or invented", if two or more people can discover the same branch of mathmatics, wouldn't that mean that it is a universal truth that could even be discovered by aliens?
As for the question of "is mathmatics discovered or invented", if two or more people can discover the same branch of mathmatics, wouldn't that mean that it is a universal truth that could even be discovered by aliens?