Recent content by TMO

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    A How do I find the change of basis matrix for the JCF of M?

    Taking ## (M + I) = 0 ## and transforming it into RREF gives ##\begin{align}\begin{pmatrix} 1& -1& 0 \\ 0& 0& 0 \\ 0& 0& 0 \end{pmatrix} \end{align}##. The non-pivot columns are two, so the eigenspace is given by ##\begin{align} v_1 - v_2 =& 0& \\ v_2 =& r \\ v_3 =& s \end{align}##...
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    A How do I find the change of basis matrix for the JCF of M?

    I need to find the change of basis matrix using eigenvectors and generalized eigenvectors. Why? Because for larger matrices I may not be able to get a nice number partition that allows me to guess the JCF. I know there's a way to do this. How do I do this?
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    A How do I find the change of basis matrix for the JCF of M?

    Let ## \begin{align}M =\begin{pmatrix} 2& -3& 0 \\ 3& -4& 0 \\ -2& 2& 1 \end{pmatrix} \end{align}. ## Here is how I think the JCF is found. STEP 1: Find the characteristic polynomial It's ## \chi(\lambda) = (\lambda + 1)^3 ## STEP 2: Make an AMGM table and write an integer partition...
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    A How to find the Jordan Canonical Form of a 5x5 matrix and its steps?

    To see the steps I have completed so far, https://math.stackexchange.com/q/3168898/261956 I think there are at least three more steps. The next step is finding the eigenvectors together with the generalized eigenvectors of each eigenvalue. Then we use this to construct the transition matrix...
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    B Solve Ax ≡ B mod C w/ Bezout's Identity

    This is a very obvious question, but I am having trouble concentrating. Let ax ≡ b mod c and let gcd(a, c) | b. How do I convert this equation into Bezout's identity so that I can use the extended Euclidean algorithm?
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    I Prove this inequality involving metrics

    For any metric ##(X, \rho)## and points therein, prove that ##|\rho(x, z) - \rho(y, u)| \leq \rho(x, y) + \rho(z, u)##. I know that this will involve iterated applications of the triangle inequality...but I still need another hint on how to proceed.
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    I Understanding the "branch cut argument"

    http://web.williams.edu/Mathematics/sjmiller/public_html/302/coursenotes/Trapper_MethodsContourIntegrals.pdf See Type 5 Integrals. I don't understand why J is equal to the original real integral multiplied by a factor of ##2\pi i##. I think the ##2\pi i## comes from the fact that as you go...
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    I An Embarrassing Question about turning a ring into a module

    Given a ring R, how exactly do I interpret it as a module? A lot of my homework assignments involve treating a ring as "a module over itself" and I don't know precisely what that means.
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    A Is the Injective Hull of an Irreducible Module in Group K?

    I think there is a theorem that for a principle ideal domain X, X is divisible iff. X is injective. Tell me, is it iff. or if? It isn't obvious to me. Could you explain why?
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    A Is the Injective Hull of an Irreducible Module in Group K?

    Let's suppose that I have an element ##e## of order ##p## in the group of complex numbers whose elements all have order ##p^n## for some ##n\in\mathbb{N}## (henceforth called ##K##), and the module generated by ##(e)## is irreducible. How do I show that the injective hull of the module...
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    A Construct a unique simple submodule

    Problem. Let ##p## be a prime integer. Let ##Z_p^\infty## be the set of complex numbers having order ##p^n## for some ##n \in \mathbb{N}##, regarded as an abelian group under multiplication. Show that ##Z_p^\infty## has an unique simple submodule. Attempted solution. The collection of all...
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    A Proving the Dual of Schanuel's Lemma

    First of all, I cannot use the fact that Q is the cokernel of the map because I do not know how he is even defining k to begin with. Are you allowed to take two objects in a diagram and say "let <foo> be a morphism between <ma> and <mi>" without giving evidence to suggest such a morphism should...
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    A Proving the Dual of Schanuel's Lemma

    I understand how he concluded that the morphism h existed (An R-module E is injective iff. for all R-module homomorphisms ϕ : M → N and ψ : M → E where ϕ is injective, there exists an R-linear homomorphism θ : N → E such that θ ◦ ϕ = ψ). But how exactly did he conclude that the morphism k...
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    A Proving the Dual of Schanuel's Lemma

    Given: the short exact sequences 0 → M → E → K → 0 and 0 → M → E' → K' → 0 where M is a left R-module and E and E' are injective left R-modules. Prove: E ⊕ K' ≅ E' ⊕ K. First, let f be the morphism represented by M → E and g be the morphism represented by M → E'. Therefore we can construct a...
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    I don't think I learned any mathematics as an undergrad

    Then I don't what to go to grad school. I'll find another use for my time.
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