Summary: My colleague is asking for my help in solving fundamental problem. They are having troubles on basic level, and I don't have time to guide them through it. How I can politely avoid wasting their time AND my time?
I am a computer scientist (research focused on machine learning and statistics) and where I work I have a mathematician colleague. He is a bit obsessed with millennium problems (things like P vs NP, SSP, etc.) and so far he has tried to come up with ways to solve these two problems, but his 'solutions' so far are poor at best mostly due to his ignorance on the subject.
Now, I admire the interest and tenacity he goes about these things. However, he doesn't know much about algorithm complexity, hasn't given me any indication that he has read about what approaches have been tried/used, keeps trying random stuff and asking me to check if I think his ideas are sound or to verify them, which I find annoying since it takes a lot of time to disprove him or to refute each of his attempts (specially because I don't want to be hostile, since I barely know him).
So, I'd like a polite way to either discourage him from working on these problems because I don't want to dedicate time to this (I need to read and study to enter a PhD program and I also believe he's clearly underestimating the problems) or to discourage him from asking me about it without being rude.