As anyone who has worked in probability knows, a random variable can sometimes behave in rather “unreasonable” ways. It may be never close to its expectation. It might exceed its expectation almost always, or almost never. It might have finite $1$st, $2$nd, and $3$rd moments, but an infinite $4$th moment. All of this poor behaviour [...]

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Ohad Klein: 41a (45a in book): "let T be ...; prove something about f" ...Ryan O'Donnell: Good catch, thank you Xi.Ryan O'Donnell: Thank you! Sorry for the delay in replying.Ryan O'Donnell: Hi Ming. Here S stands for a fixed (non-random) subset of [...Xi Wu: typo: "our definition of $\mathbf{Inf}_i[f]$ from Chapter 2....Chengyu: Ex 2.c It should be "Suppose ... is an LTF with $\textbf{E}...Ming: I confuse the notation S in Fact 1.7. I wonder that the sym...