With in each post, questions should be numbered so that they might be refereed to individually.

All posts should be labeled with categories to help with their organization.

Questions which are harder then the typical introductory question should be labeled with “*”:

- (*) = a reasonable questions but more difficult then the most basic.
- (**) = either more involved or requiring a specific flash of insight
- (***) = challenge problems for the best students at that level
- (****) = challenging problems in an absolute sense
- (*****) = open questions whose solution is not known

Though out the text \(\mathbf{E} X\) should be used to denote expectation of a random variable \(X\) and \(\mathbf{P}(A)\) for the probability of an event \(A\).