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@AkivaWeinberger The real question behind this is that with this relation i should be able to say something about infimum, supremum, minimum, maximum of U
I don't think it makes a difference, countable limit ordinals are limits of sequences of length $\omega$ and I don't see why it wouldn't work for higher ones
I'm trying to remember a property/method of proving something in the measure theory subject. I think there something along the lines of 'if I want to prove something for the borel sigma algebra, I only need to prove for those sets(open intervals, or close intervals) which will create the sigma algebra through countable intersection, union and complementar op
is there a binding order (or preference) to the use of a negation symbol "-" with an exponent? -x^2 -- which is grouped: the square to the symbol "x" or the negation?
@Liad Thanks. Do you know how I can prove that if $X = \sum a_n X_n$ where the $X_n$ are Rademacher variables, then $E(e^{tX}) \le e^{t^2/2}$ for all $t\in \Bbb R$ ?
