Hello categorists I don't know what to make of the silence to my question. This is the easiest question i have. I can't believe it is so difficult. It is not like i am asking you to solve the problems. There must be some important open problems in ordinary category theory. There are plenty of them in the theory of algebras and in representation theory, so there should be more of them in category theory. Especially if you broaden the boundaries a bit of what ordinary category theory is. Take for instance: model categories, categorical logic, categorical quantization, topos theory-locales-sheaves. But i had originally pure category theory in mind. Best regards Rafael Borowiecki [For admin and other information see: http://www.mta.ca/~cat-dist/ ]