Probability theory and mathematical statistics, the former is probability, the latter is the law of large numbers, mainly five formulas of probability distribution, common distribution functions (such as 0- 1 uniformity, etc. ), distribution function, probability density, probability distribution (discrete and continuous), numerical features (1 dimension or more) and two-dimensional then. As long as you understand the law of large numbers and do it, you don't need to understand it. Finally, the maximum likelihood estimation. Estimation unbiased estimation is mainly these.