Ergodic Theory of Groups, SS 2020

Prof. Dr. C. Löh / J. Witzig

Correction log for the lecture notes:

Date Page Correction
22.04.2020 A.5 Added Hausdorff hypothesis to Definition of outer Radon measure
29.04.2020 13 Proposition 1.2.9, part 2: "irrational" corrected to "rational"
03.05.2020 9 Remark 1.1.7: added second countability assumption
07.05.2020 33 Theorem 1.3.8: corrected two typos in the proof (a sign in the definition of \mu_n and an exponent in the last line)
07.05.2020 41 Proposition 1.4.24: corrected the inconsistent use of A and B in the proof
12.05.2020 Week 4 Exercise 3.3: clarified "natural numbers"
19.05.2020 53 Proposition 2.1.8: emphasised that the group needs to be infinite
19.05.2020 Week 5 Exercise 4.1: Introduced \gamma.
20.05.2020 Week 6 Exercise 5.3: Added mixing hypothesis for \beta.
26.05.2020 62 Definition 2.1.27: invariant vectors should be non-zero
26.05.2020 69 Quick check 2.2.8: Added missing reference.
26.05.2020 73 proof of the maximal ergodic theorem: Added missing \mu(E_\alpha) [twice].
03.06.2020 68 Added a comment about proving the L^1-version via L^\infty or via L^2
03.06.2020 76 Definition 2.2.17, part 1: corrected d-adic expansion
04.06.2020 A.10 Example A.1.30: corrected the conditional expectations
05.06.2020 72/Week 7 Proposition 2.2.12/Exercise 6.3: changed summation range in definition of g_n
05.06.2020 Week 7 Exercise 6.4: corrected definition of r_A (only n > 0 should be considered)
12.06.2020 92 Definition 3.1.1: Added the measurability condition for R
12.06.2020 98 Definition 3.1.16: One of the f's was supposed to be a g.
12.06.2020 101 Figure 3.1: Now the phi's can actually be bijections.
16.06.2020 97/98 Proof of Proposition 3.1.13: For non-free actions, we have to be more careful to make the A_\gamma pairwise disjoint.
16.06.2020 102 Example 3.2.5: For the parts on the Cayley graphs, we need freeness.
23.06.2020 115 The \phi_{\theta,j} are from \Omega (not from \Theta_0 \cup \Theta_0^{-1}. This is also corrected in the notes (p. 5, in "green").
24.06.2020 Exercise 10.4: URL corrected
30.06.2020 137 Corollary 3.3.27: replaced cost by cost -1.
01.07.2020 129/130 Proof of Proposition 3.3.15: uses free actions now instead of essentially free actions (to avoid complications in the ergodic decomposition argument)
02.07.2020 129/Week 12 Lemma 3.3.16/Exercise 11.2: Added the missing freeness condition.
04.07.2020 notes 30.06. The "open" problem was not open.
08.07.2020 148 2 => 1: added missing integral
10.07.2020 138 Quick check 3.3.30: corrected the computations involving rg F_2
18.07.2020 153 Theorem 4.2.8: In general, A is not a strict section (but meets only almost every orbit).
21.07.2020 168 first line: added "\perp"
22.07. 175 Outlook 5.3.2: rg \pi_1 (M) instead of rg M
22.07. 176/177 proof of Theorem 5.3.7: 1/v_3 instead of v_3 (twice)
29.07. 19 Exercise 1.2.25: index typo
29.07. 70 Quick check 2.2.8, part 2: factor n instead of 1/n
29.07. 84 Corollary 2.3.7, proof of part 2: typos in formulas
29.07. 118 Theorem 3.2.34: "essentially free" was missing as hypothesis
29.07. 119 Example 3.2.37: typo in subscript
29.07. 138 Quick check 3.3.30, part 2: 0+0+1 is now 1 :)
29.07. 162 Theorem 4.3.3: "S" instead of "K"