SCOTTISH MATHEMATICAL SCIENCES TRAINING CENTRE - PROBABILITY STREAM ---- NOTES 1. The proposed syllabus is intended to provide the core skills in probability necessary for students undertaking research in probability and statistics. With regard to the latter, it probably goes considerably beyond what is needed. The course is also intended to be accessible to students in other areas of mathematics. 2. Although most students may be expected to have had some prior training in at least elementary probability, the level of such skill is likely to be extremely variable. Hence the rapid revision corresponding to the first 4-5 lectures below is felt to be essential. The treatment of this material is likely to contain a certain amount that is new to everybody. ---- PROPOSED SYLLABUS FOUNDATIONS 1. Probability spaces. SZa Events, probability measures, random variables: definitions, axioms, basic results, elementary calculations, examples, simple combinatorics. 2. Conditioning and independence. SZa Conditional probability, chain rule, partition theorem (law of total probability). Independence of events and random variables. Bernoulli schemes. 3. Random variables and their distributions. TK Distribution functions, probability (mass) functions, probability density functions, moments, simple inequalities (Markov, Chebychev), transformations. Moment generating functions (briefly). 4. Joint distributions and independence. TK Joint distributions, marginal and conditional distributions. Independence: factorisation of joint distribution and moment generating function, moment properties. Covariance, correlation, multivariate normal distribution. 5. Important special distributions. TK Binomial, Poisson, geometric, uniform, exponential and normal distributions: definitions, properties and the relations between them. 6. Convergence and related concepts. TC Convergence in distribution, in probability, in $L^p$, a.s. convergence, and relations between them. Uniform integrability. Borel-Cantelli lemmas. Weak law of large numbers. 7. Sequences of independent random variables. TC 0-1 law Strong law of large numbers (proof for finite fourth moment case only). Central limit theorem. Possible extensions to non-independent sequences. CONDITIONAL EXPECTATION AND MARTINGALES (DISCRETE PARAMETER SPACE) 8. Conditional expectation and martingales. AD/IG Conditional expectation definition, tower property. Martingales (including sub and super): definitions, optional stopping theorems and applications. 9. Martingale limit theorems and applications. AD/IG (Proofs for $L^2$ theory only.) Ruin problems. MARKOV PROCESSES (COUNTABLE STATE SPACE) 10. Markov chains in discrete time. XM/SZ Definitions, transition matrix, evolution of probability measure and simple calculations. Strong Markov property. Irreducible chains: existence and uniqueness of stationary distributions, relation to recurrence and transience properties detailed balance, limiting behaviour, ergodic theorems. 11. Poisson processes on the real line. XM/SZu Homogeneous processes (definition via Poisson counts), superposition and splitting theorems, further properties: times between successive events are i.i.d. exponential, conditional uniform property. Heterogeneous processes. 12. Markov processes in continuous time. XM/SZu Definition, transition rates, evolution of probability (forward and backward equations). Jumping chains. Irreducible processes: stationary and limiting distributions, detailed balance. Applications. STOCHASTIC MODELLING AND SIMULATION 13. Stochastic models I SF Simple population processes, queueing and communication systems, 14. Stochastic models II SF Random graphs, epidemic models. 15. Simulation techniques. Inverse transform, acceptance based-techniques. SZa Metropolis-Hastings algorithm. Simulation of stochastic processes. BROWNIAN MOTION AND ELEMENTS OF STOCHASTIC CALCULUS 16. Brownian motion. IG Levy's construction of the Wiener process. Quadratic variation. Stochastic integral. Ito's formula. Martingale characterisation of the Wiener process. Martingale representations. Girsanov's theorem. 17. Stochastic differential equations (SDEs). IG Notion of solutions. Existence and uniqueness theorems. Stochastic representation of the solutions of elliptic and parabolic PDEs. Numerical solutions. 18. Applications of stochastic differential equations. IG Financial models: option pricing. SDEs arising in biology. A brief introduction to filtering and control of stochastic systems. ---- ASSESSMENT 3-4 homework assignments evenly spaced throughout the course.