Recent content by chaotixmonjuish

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    Oscillation of a closed subinterval

    The definitions of oscillation of a set and point respectively: \omega_f(A)=\sup\limits_{x,y\in A}f(x)-f(y)| \omega_f(x)=\inf\{\omega_f(x)=\inf\{\omega_f(x-\epsilon, x+\epsilon)\cap A) : \epsilon > 0\}
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    Oscillation of a closed subinterval

    Given \epsilon > 0 , suppose \omega_f(x) < \epsilon for each x \in [a,b] . Then show there is \delta > 0 such that for every closed interval I \in [a,b] with l(I)< \delta we have \omega_f(I) < \epsilon . My first approach to this was trying to think of it as an anaglous to the definition...
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    Induction to demonstrate n-1 is a natural number

    The question is as follows: Using an induction argument if n > 1 is a natural number then n-1 is a natural number. P(n)=n-1 such that n-1 is a natural number Following the steps: Base case: n=2, P(2)=1 which is a natural number. We fix a natural number n and assume that P(n)=n-1 is...
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    Uniformly Bounded Functions: Proving Sequence Convergence

    Prove that a sequence of uniformly convergent bounded functions is uniformly bounded. Attempt at proof: So first we observe the following: ||fn||\leqMn. Each function is bounded. Also, |fn-f|\leq\epsilon for all n \geq N. First off, we observe that for finitely many fn's, we have them...
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    Mapping Surfaces: Show F is Differentiable

    Let M be a simple surface, that is, one that is the image of a single proper patch x: D -> R3. If y: D -> N is any mapping into a surface N, show that the function F: M -> N such that: F (x(u, v)) = y(u, v) for all (u, v) in D is a mapping of surfaces. To demonstrate this one does the...
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    Shape Operators and Eigenvalues

    This is probably falls within a problem of Mathematica as opposed to a question on here but I have a question about the following: Given some cylinder with the shape operator matrix: {{0,0},{0,-1/r}} We get eigenvalues 0 and -1/r and thus eigenvectors {0, -1/r} and {1/r, 0} by my...
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    Computational Proofs for Tangent Vectors and Differential Geometry of Surfaces

    Homework Statement Given the following: Some surface M: z=f(x,y) where f(0,0)=fx(0,0)=fy(0,0) and U =-f1U1-fyU2+U3}/Sqrt[1+fx2+fy2] and u1 = U1(0) u2 = U2(0) are vectors tangent to M at the origin 0. We want to prove S(u1)=fxxu1+fxyu2 My problem here is conceptually wadding through this...
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    What is the surface parametrization for rotating y=Cosh(x) about the x-axis?

    I'm having problems understanding surface parametrization from differential geometry. We are given two general forms for parametrization: \alpha(u,v) = (u,v,0) and x(u,v)=(u,v,f(u,v)) This is one I'm especially stuck on: y=Cosh(x) about the x-axis \alpha(u,v)=(u, Cosh[v],0)...
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    Orientation preserving reparameterization

    http://tinypic.com/r/xqf446/7 ^^This is the hint I mentioned. http://tinypic.com/r/24101at/7 ^^This is the problem its referencing. I'm having trouble figuring out what it wants me to do for part (a). When it mentions denoting a f and g as follows: f = U_1.(a/||a||) = (1,0).(a/||a||) =...
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    Orientation preserving reparameterization

    This is from O'Neil's differential geometry. I'm having trouble parsing through the problem/hint. Given any curve a that does not pass through the origin has an orientation-preserving reparameterization in the polar form: a(t) = (r(t)*Cos(V(t)),r(r)*Sin(V(t))) where r(t)= ||a(t)||...
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    Bijection between Orbit and Stabilizer

    Great, it all makes sense. However, how does this bijection prove that O*Gx:K=G. To me it just proves they are equal, but that can't always be the case.
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    Bijection between Orbit and Stabilizer

    The very last function you defined is from the orbit to the stabilizer (I know its a bijection but I just want to make sure).
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    Bijection between Orbit and Stabilizer

    Sort of, but I'm getting kind of thrown off by his notation. So the function that is defined is sending f: g*H---->Orb(x) where H=G/Gx. Is this just saying that f(gh)=gx or f(g)=gx because H is everything that doesn't move x so its not really worth mentioning.
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    Bijection between Orbit and Stabilizer

    So I know this is the orbit-stabilizer theorem. I saw it in Hungerford's Algebra (but without that name). So we want to form a bijection between the right cosets of the stabilizers and the orbit. Could I define the bijection as this: f: gG/Gx--->gx Where H=G/Gx f(hx)=gx h in H ^ Is that...
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    Group Action and a Cartesian Product

    For the sake of group theory, when g operates on y in Y, would it need to be using a different operator such as '$'
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