When I had time to study math, I finished off the section on sets. I learned what a universal set is (the set which all the currently discussed sets are subsets of), as well as what the complement of a set is (it is the set of all elements in the universal set except the elements belonging to the set being operated on). I also learned about De Morgan's laws in relation to set theory, including how to prove them. The first law states that the complement of the union of two sets A and B is equal to the intersection of the complements of the two sets A and B. The second law states that the complement of the intersection of two sets A and B is equal to the union of the complements of the two sets A and B. One of the problems in the problem set was proving De Morgan's second law. It took me about an hour to figure out, but I eventually proved it by doing a lot of substitution and logic.
Reposted from http://invisiblegdev.blogspot.com/