M393c Fall 2018
This schedule is tentative.



Week
Dates
Daily schedule
Homework
1
Aug 27-31
Mon: no class

Wed: first day of class. The plan for the first few lectures is to cover sections 2.1-2.6 from the Lyons-Peres book which you can download here.

We covered discrete differential operators and harmonic functions.

Fri: We went over the Gambler's ruin problem, introduced electrical networks and proved a formula relating the strength of the current to the probability that random walk hits Z before returning to a.

Register to vote! (The deadline is Oct 9)

Voting info (written for UT students)

Homework #1
From the Lyons-Peres book: 
2.5, 2.8, 2.13, 2.18, 2.61, 2.65, 2.67.

Due: Mon Sept 10.
2
Sept
3-7
Mon: Labor Day (no class).

Tues: last day graduate students may register and pay tuition without the approval of the graduate dean.

Wed: The plan for the week is to continue with chapter 2 (random walks and electrical networks). We discussed Green's function, current and random walks.

Fri: We discussed energy, decomposing l^2(E), current minimizes energy. (This is all in 2.4 of Lyons-Peres)

3
Sept
10-14
Mon: The plan for the next 2 lectures at least: series law, parallel law, Rayleigh's monotonicity theorem, Nash-Williams, Polya' Theorem, rough embeddings, transience/recurrence.

Wed:

Fri: We finished 2.5 and covered 2.6 (quickly). We won't go over the rest of chapter 2 (it is interesting but not directly related to future developments).

Last day to drop a class for a possible refund.
Last day a graduate student may, with the required approvals, add a class
Homework #2
From the Lyons-Peres book: 
2.54, 2.71, 2.104.

Due: Mon Sept 17.

Also: if you're reading along, we'll start on chapter 3 next week.

Solutions
4
Sept 17-21
Mon: we discussed flows on directed networks, admissible flows, branching number, its relation to growth rate, and started on the Max Flow-Min Cut Theorem.

Wed: The plan is to continue with Max Flow-Min Cut and from there on to homesick random walk on trees.

Fri:
Homework #3
From the Lyons-Peres book: 
3.4, 3.5, 3.16.

Due: Wed Sept 26.

Also: if you're reading along, we'll probably start on chapter 4 next week.
5
Sept 24-28
Mon: Prof. Baccelli will give a guest lecture (on point processes and continuum percolation).

Wed:

Fri: We started Chapter 4 by going over Wilson's Algorithm.

6
Oct
1-5
Mon: The plan is to continue with Chapter 4 (uniform spanning trees). We might finish in one day because we're not going over 4.3.

As needed, we'll set up individual meetings for choosing projects.

Wed: We started on percolation theory, a little of 5.2 and 7.4.

Fri: We covered 5.2 and a little of 5.3 (percolation on trees).
Homework #4
From the Lyons-Peres book: 
4.23, 4.29, 4.30.

Due: Mon Oct 8.

Also: if you're reading along, we'll probably start on chapter 4 next week.
7
Oct 8-12
Mon: The plan is to finish 5.3 (p_c = 1/br for trees) and start chapter 6 (isoperimetry). The subject starts with amenability of graphs. Sometime later in the week, I plan to lecture on amenability for groups.

Wed: We covered amenability of groups.

Fri: We started on 6.1 (amenability of graphs).
Homework #5
From the Lyons-Peres book: 
5.38, 6.1, 6.3.

Due: Mon Oct 15.

Also: if you're reading along, we'll probably start on chapter 7 next week.
8
Oct
15-19
Mon: We started on spectral radius and asymptotic behavior of transition probabilities.

Wed: We went over spectral radius.

Fri: (soft) deadline for choosing a project. We discussed ergodicity and the number of infinite components of percolation. We barely started introducing unimodular networks. The paper introducing unimodular networks is here.
Homework #6
From the Lyons-Peres book: 
6.19, 7.4, 7.10

Also: prove that the d-regular tree, thought of as a unimodular network (rooted anywhere) is a limit of unimodular networks supported on finite graphs.

Due: Mon Oct 22.

Next week we'll be going over select sections of chapter 7 and unimodular networks.
9
Oct
22-26
Mon: The plan is to continue with unimodular networks and the number of ends of infinite components in Bernoulli percolation.

Wed: We discussed graphings and unimodular networks to show that the infinite percolation cluster rooted at the origin of a Cayley graph is a unimodular random rooted graph.

Fri: We discussed how the # of ends in a unimodular random graph.
Hwk #7 (click to open a pdf file)
10
Oct 29
-
Nov 2
Mon: No office hours in the morning. (Instead I'm holding office hours for a different class). I'll still have office hours after class as usual. The plan is to go over amenability of unimodular random graphs.

Wed: We showed that amenable unimodular random networks have at most 2 ends a.s.

Fri: We started on Gibbs random fields and showed that Gibbs and Markov random fields are the same (on finite graphs).
no homework due next week.
11
Nov
5-9
Mon: The plan is to introduce the Ising, Potts and random-cluster models using Grimmett's books and Pete's notes (from online resources).

Tues: Voting Day!

Wed: The plan to continue with the random-cluster model on Z^d and on trees.

Fri: I explained why there is a nontrivial phase transition in the random cluster model on Z^d for d>1.
Homework #8
From Grimmett's
Probability on Graphs: 8.2, 8.8, 8.9.


Due: Mon Nov 12.
12
Nov
12-16
Mon: I'll sketch some of the latest developments on the random cluster model in Z^2 (mostly by sketching the Harris-Kesten Theorem about percolation) and start on the Ising model on trees by way of the Evans-Kenyon-Peres-Schulman paper "Broadcasting on trees and the Ising model"

Wed: Probably, we'll still be on the Ising model on trees.

Fri: I think that by Friday, we'll be starting with Gibbs measures on random sparse graphs ala Amir Dembo and Andrea Montanari. We might start with Wormald's survey on random regular graphs.

13
Nov
19-23
Mon:

Wed: Thanksgiving (no class)

Fri: Thanksgiving (no class)

14
Nov
26-30
Mon: Last day a graduate student may change registration in a class to or from the credit/no credit basis.

Wed:

Fri:

15
Dec
3-7
Mon:

Wed:

Fri:Last day to submit master’s report, recital, thesis, doctoral dissertation, or treatise to the graduate dean

16
Dec
10-14
Mon: Last class day. Also last day a graduate student may, with the required approvals, drop a course or withdraw from the University.

Wed:

Fri:

Sat: Our final exam is officially on Saturday 2-5pm.