Course Program
The course is built as a direct continuation of ETMT: overlaps with it are compressed to brief reminders, and the freed-up time is devoted to topics that are absent from self-contained probability theory courses or are given only in passing (uniform integrability, the Borel-Cantelli lemma and the zero-one law as a separate topic, the Lindeberg-Lyapunov conditions, conditional distributions with a Gaussian forecast). The throughline is computational technique for the continuous case: Jacobians, convolutions, and gamma- and beta-integrals.
Part 1. Probability on the Foundation of Measure. Convergences
- The language of probability theory (1-2 seminars, βpaying off debtsβ from ETMT). Kolmogorovβs axioms; independence and the criterion via \(\pi\)-systems; random variables and distributions; expectation as a Lebesgue integral, change of variables, generalized densities.
- Random vectors. Joint distributions, multivariate distribution functions; the density transformation formula (Jacobian); marginals; independence criteria; the main continuous distributions in practice.
- Convolution. Covariance and inequalities. The convolution formula as a technique; covariance and correlation in the general case, the covariance matrix; Jensenβs, Lyapunovβs, and Cauchy-Bunyakovsky-Schwarz inequalities.
- Convergence of random variables. The complete diagram of the four types of convergence with counterexamples; the criterion for almost sure convergence; inheritance of convergence, Slutskyβs theorem; uniform integrability and convergence of moments.
- The Borel-Cantelli lemma and the zero-one law. Both parts of the lemma; problems on \(\limsup\) of events; tail \(\sigma\)-algebras, Kolmogorovβs zero-one law; optional β the three-series theorem.
- Laws of large numbers. The Cantelli strong law of large numbers; Kolmogorovβs inequality, the Kolmogorov-Khinchin theorem; Toeplitzβs and Kroneckerβs lemmas; Kolmogorovβs strong law of large numbers; applications: the Monte Carlo method, normal numbers.
Midterm exam 1.
Part 2. Limit Theorems and Conditional Constructions
- Weak convergence of probability measures. Convergence in the main sense; Alexandrovβs theorem; tightness of families of measures; Prokhorovβs theorem.
- Characteristic functions. Properties, computational technique; moments and derivatives; the uniqueness theorem, the inversion formula; the Bochner-Khinchin theorem.
- The central limit theorem. The continuity theorem; proof of the CLT; the Lindeberg and Lyapunov conditions; the Berry-Esseen inequality; the de Moivre-Laplace theorems, the Poisson approximation; optional β the law of the iterated logarithm (statement).
- Gaussian vectors. Three equivalent definitions; independence \(\Leftrightarrow\) uncorrelatedness; density, linear transformations; the multivariate CLT.
- Conditional expectation. The discrete case; definition via a \(\sigma\)-algebra; the complete set of properties (the foundation for martingales in the stochastic processes course).
- Conditional distributions and computing conditional expectation. Conditional densities, \(\mathbb{E}[\xi \mid \eta = y]\); the best forecast in \(L^2\); the Gaussian conditional expectation as a linear forecast β a bridge to regression in statistics and to Gaussian processes.
Midterm exam 2.