Introduction to Stochastic Processes


  • Basic Information
    • Instructor : Siva Athreya .
    • Email : athreya@isibang.ac.in or athreya@icts.res.in
    • Scoring: Final Exam: 50%, Midterm Exam: 25%, Homework: 5%, Quiz: 20%

  • Syllabus:
  • From B.Math. (Hons.) III Year students-Brochure
    • Discrete-Time Markov Chains: Classification of states, Stationary distribution, reversibility and convergence. Random walks and electr ical networks. Collision and recurrence.
    • Discrete-Time Martingales: Optional Stopping theorem, Martingale convergence theorem, Doob’s inequality and convergence.
    • Branching Processes: Model definition. Connection with martingales. Probability of survival. Mean and variance of number of individuals.
    • Basic Probabilistic Inequalities and Applications: First and Second Moment methods. Applications to Longest increasing subsequences, Random k-Sat problem and connectivity threshold for Erdos-Renyi graphs. Chernoff bounds and Johnson-Lindenstrauss lemma.

  • References and Texts
  • Classes:
  • Day and Time : Wednesday : 2:00-2:50pm, 3:10pm-4:00pm, 4:10pm-5:00pm.

  • Homework:
  • There will be regular Homework assignments given during the course. The problems given there will be a small selection so please do try other problems for practice from the texts. You are encouraged to work together on solving the problems but please write up solutions without consulting anyone else.



Week # Notes in Each Week Homework
(Due Dates)
Topics
1 Week-1 Notes Homework 1
July 29th, 2026.
2 Week-2 Notes Homework 2
August 5th, 2026.
  • Section 1.2 in [LHdHGVZ]: Stopping times
  • Section 1.3 in [LHdHGVZ]: Ruin Probability
  • Section 1.4 in [LHdHGVZ]: Reflection Principle.
3 Week-3 Notes Homework 3
August 12th, 2026.
  • Section 1.5 in [LHdHGVZ]: Arc Sine Law.
  • Section 2.1-2.3 in [LHdHGVZ]: Infinite Length Random Walks
  • Definition of Markov Chain
4 Week-4 Notes Homework 4
August 19th, 2026.
  • Examples of Markov Chain
  • Stationary Distribution
  • Recurrence and Transience
5 Week-5 Notes Homework 5
September 2nd, 2026.
  • Hitting times.
  • Classification of States
  • Recurrence for Random walk on Weighted Graphs.
6 No Class Worksheet
September 2nd, 2026.
  • Irreducible Markov Chain
  • Period of a Markov Chain
7 Week-7 Notes Homework 6
Not Due.
  • Stationary distribution: Existence and Uniqueness
  • Convergence
8 Week-8 Notes Homework 7
  • Conditional Expectation for Discrete Random Variables
  • Definition of Martingales
  • Tower Propety
9 Worksheet(s) Homework 8
  • Sampling from a distribution using a Markov Chain.
  • Sampling a uniform spanning tree.
10 Week 10 Notes Homework 9
  • Stopped Processes
  • Optional Stopping Theorem
11 Week 11 Notes Homework 10
  • Kolmogorov Maximal Inequalities
  • Martingale Convergence Theorem
12 Week 12 notes :
Homework 11
  • Time to fixed pattern.
  • Longest increasing subsequences in a random permutation.
13 Week 13 Notes Homework 12
  • Connectivity Threshold for Erdos-Renyi Graphs
Last Modified: 23rd, October 2026. ISI Courses Page