Recent content by e12514

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    Surface Homeomorphism Between Cubes and Spheres?

    Is it true that the surface of a (hyper)cube in Rn is homeomorphic to Sn-1? Or only for particular n?
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    Weakly Convergent l^p Sequences: Boundedness and Convergence in C

    For 1 < p < oo it is true that: If we have a sequence ( x_n )_(n >= 1) in l^p that converges weakly to zero then that implies the x_n are uniformly bounded and that ((x^{m})_n) -> 0 in C (as n -> oo) for each fixed m. (where l^p is the space of p-summable sequences of complex numbers, and I...
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    Are Ratios of IID Exponential Variables Independent of Their Sample Average?

    Are X/Y and X+Y independent (given X and Y are)? I can't seem to show that in general...
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    Are Ratios of IID Exponential Variables Independent of Their Sample Average?

    Suppose I have a sample X_1, ..., X_n of independently, identically distributed exponential random variables. One result I deducted was that the ratio of any two of them (eg. X_1 / X_2) is independent of the sample average 1/n * \sum_{i=1}^{n} X_i. (Aside: that ratio, as a random variable...
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    Unravelling the Mystery of Poles and Residues

    Thanks mate. Are there any good online ebooks with more examples like these available that you know of? Most of the ones I've searched/seen have either no examples or only very straightforward ones like 'polynomial denominators'...
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    Unravelling the Mystery of Poles and Residues

    How should we go about finding orders and residues in those cases then?
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    Unravelling the Mystery of Poles and Residues

    I still don't quite fully understand about the order of poles and calculating residues. Take f(z) = 1/sin z at z=0 for example. When I try putting that into Laurent expansion about z=0, 1/ sin z = 2i/ (e^z - e^(-z)) = 2ie^(-z) / ( 1 - e^(-2z)) = 2ie^(-z) [ 1 - e^(-2z) + e^(-4z) - e^(-6z) +...
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    Measure of limit of decreasing sequence

    If E_1, E_2, ... is a sequence (of subsets of R^n) that decreases to E (i.e. E_m+1 is a subset of E_m for all m, and E = intersection of all the E_m's) and some E_k has finite (lebesgue) measure, i.e. lambda(E_k) is finite it is a known result that the measure of E is equal to the limit of...
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    Probability of unions/intersections

    Pr( ∪_(n from m to k) ((A_n) ∩ ((A_(n+1))^c)) ) = Pr( ∪_(n from m to k) (A_n) ) - Pr( (A_k) ∩ (A_k+1) ) or the probability of [ the union (where n goes from m to k) of [ A_n intersect (A_(n+1) compliment) ] ] is equal to the probability of [ the union (where n goes from m to...
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    Probability of unions/intersections

    That (induction) is exactly what I've been attempting to use to convince myself that it is true. I've got the base step (k=m+1) which was (for me) expand-able to see that both sides are equal. However I couldn't get through the inductive step. Perhaps it is false then? Or it could also just...
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    Probability of unions/intersections

    Is it true that Pr( ∪_(n from m to k) ((A_n) ∩ ((A_(n+1))^c)) ) = Pr( ∪_(n from m to k) (A_n) ) - Pr( (A_k) ∩ (A_k+1) ) where A_1, A_2, ... is any sequence of sets. Well, for the (k=m+1) case I am convinced since I can see they are equal after expanding both sides out, so for...
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    Understanding Borel-Cantelli Lemma

    Let (A_n)_n>=1 be any event in some probability space { Omega, F, P }, then (i) SUM_n (P(A_n)) < oo => P( limsup_n->oo (A_n) ) = 0 (ii) If in addition the A_n are independent then P( limsup_n->oo (A_n) ) <1 => SUM_n (P(A_n)) < oo Does that mean if the A_n are independent...
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    Is there a faster way to do this?

    Then the factor is a field! Yay, fantastic! Thanks! This shows that I need to do a lot of extra reading on stuff that is not taught in order to fully understand the material.. I've never heard of a pid before, unless it's lying on some fresh page that I've never looked at in our notes, or it's...
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    Surjective group homomorphism

    Hmm... that's true. Maybe there was a typo on the question. Unless there is some other interpretation for what C* is...
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    Is there a faster way to do this?

    Z/p [x] consists of polynomials in x with coefficients in a field Z/p. I is an ideal of Z/p [x] generated by some irreducible polynomial i(x) in Z/p [x] (let's say I is generated by an irreducible polynomial i(x) of degree 3 in Z/p [x]) The factor (or quotient) (Z/p [x])/I = (Z/p...
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