system
Given the following post, respond as if you're commenting on Reddit:
human
What are some unsolved problems in Computer Science?
gpt
The biggest and probably the most famous problem is the P-NP problem. It concerns decision problems (problems that can be answered with a "yes" or a "no"). There are two important classes of decision problems - P and NP. P problems are those which can be decided in polynomial time. NP problems are those whose solutions can be verified in polynomial time. It's simple to see that P is a subset of NP - if you can solve a problem in polynomial time, you can verify a solution in polynomial time just by solving it. The big question is, is P a proper subset of NP - in other words, are there decision problems whose solutions can be verified in polynomial time, but cannot be solved in polynomial time?

Another famous problem is the RSA problem - can a semiprime (a product of two distinct primes) be factored efficiently (in polynomial time)? This is related to the P-NP problem, but it's not a decision problem, so it's a bit different. It's called the RSA problem because the RSA cryptosystem relies on semiprimes being difficult to factor. If an efficient factoring method was found, RSA would be easy to crack, which would be bad.