Recent content by rochfor1
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Graduate Generating functions and summation
No. w_1=1 and w_2=0 shows it's impossible, as w_n = w_1^n. -
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Undergrad Proving Vector Space Axioms: (-1)u=-u
Ok, here goes: -u is the unique element such that u + (-u) = 0 = (-u) + u, so all we have to do is show that (-1) u has this property. That's not too bad: u + (-1)u = (1 + -1)u = 0u = 0. (The other case is identical.) The first equality follows from the distributivity of scalar...- rochfor1
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- Forum: Linear and Abstract Algebra
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Real roots of complex polynomials
R is a line in C, what can you say about the convex hull of collinear points?- rochfor1
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- Forum: Calculus and Beyond Homework Help
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Applying Zorn's Lemma (Maximal Subspace)
Take out infinite (which is not necessarily true) and you've got it.- rochfor1
- Post #6
- Forum: Calculus and Beyond Homework Help
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Applying Zorn's Lemma (Maximal Subspace)
We're trying to prove that U exists, so we can't use it as the upper bound here. Also, you don't have to find an upper bound for the whole poset, that's what Zorn's lemma gives. You just need to find an upper bound for an arbitrary chain in the poset. A subset S of our poset is a chain if A,B...- rochfor1
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- Forum: Calculus and Beyond Homework Help
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Graduate Proving Finite Lebesgue Measure of A When B Is Contained Within
The reason you're having trouble proving it is that it's not true (at least when you consider the Lebesgue measure on the whole real line). Consider the trivial example of A=all reals and B = (-\infty,0)\cup(0,\infty). For which m(A\B)=m({0})=0, but A has infinite measure. For a somewhat less... -
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Graduate Graphing functions of two complex variables.
You're not going to have much luck as the domain is four dimensional and therefore difficult to visualize.- rochfor1
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- Forum: Topology and Analysis
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What is the destribution function of U(2,4)
What is U(2,4)?- rochfor1
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- Forum: Calculus and Beyond Homework Help
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Applying Zorn's Lemma (Maximal Subspace)
So what do we need to apply Zorn's lemma? A partially ordered set in which every chain has an upper bound. Let's let our partially ordered set be the family of all subspaces of V whose intersections with W gives X ordered by inclusion. Given a chain in this poset, can you find a natural upper...- rochfor1
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- Forum: Calculus and Beyond Homework Help
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Graduate Why is the Empty Set Open in a Metric Space?
There is no boundary of the whole space! There is nothing outside of the whole space. -
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Limit Question (Using logarithm and L'Hopital's Rule)
Note that ln(a/b) != ln a/ln b- rochfor1
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- Forum: Calculus and Beyond Homework Help
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Undergrad How to Prove Rank(A) Equals Rank(ATA)?
Try proving \operatorname{ker} A = \operatorname{ker} ( A^\top A).- rochfor1
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- Forum: Linear and Abstract Algebra
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Graduate How can I adjust the index in summation notation for the Frobenius method?
Why is that silly? When k = 0, you have x^-1 in your original summation. -
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What Is the Dimension of Subspaces U and W in a Vector Space V?
What is the definition of basis?- rochfor1
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- Forum: Calculus and Beyond Homework Help
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Finding System Solutions of the system Ax=0; A being a matrix
Yes, since this matrix is indeed invertible.- rochfor1
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- Forum: Calculus and Beyond Homework Help