Recent content by altcmdesc

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    Schools Alg. Geometry/Topology Grad Schools?

    Great. A somewhat related topic is Algebraic K-Theory... so what about schools for that? Since it isn't a huge subject you don't really hear about schools having math departments which are strong in the field..
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    Schools Alg. Geometry/Topology Grad Schools?

    I'm finding myself interested in studying something like Algebraic Geometry or Algebraic Topology for graduate school, and I'm just wondering what schools are out there at have strong programs in these areas? I already know about Columbia, Michigan, Texas, and Utah for AG, and about UChicago for...
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    What subfields of math should I study next?

    I've had a graduate course in algebra, so I'm familiar with the basics of modules and Galois theory -- both of which I find interesting. It's hard for me to be more specific and say exactly what I like about algebra/category theory, but I guess it's the level of abstraction and the way that one...
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    What subfields of math should I study next?

    Nothing? Surely someone can give a little input from their perspective.
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    What subfields of math should I study next?

    Just looking for a little advice on subfields of math to study up on. I'm asking since it's hard for me to know what some subfields are like looking at them from a "bottom-up" perspective. I'm a huge fan of algebra/category theory, but I feel like some of the problems can be a bit uninspired...
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    Proving an or statement in mathematical proofs

    Proving an "or" statement What is the general procedure when proving a statement like "A implies B or C"? Is it more common to assume A and then split into cases (i.e. case 1: A implies B, case 2: A implies C, therefore A implies B or C)? Or is it more common to assume A and that one of B or C...
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    Direct Sum vs Direct Product of Rings: Irish & Rosen

    What's the difference (if any) between a direct sum and a direct product of rings? For example, in Ireland and Rosen's number theory text, they mention that, in the context of rings, the Chinese Remainder Theorem implies that \mathbb{Z}/(m_1 \cdots...
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    Number Theory Books: Find the Right Book for You!

    I'm looking for a good number theory book which doesn't hesitate to talk about the underlying algebra of some of the subject (e.g. using group theory to prove Fermat's Little Theorem and using ring theory to explain the ideas behind the Chinese Remainder Theorem). I'm still an undergraduate, so...
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    Solution to Challenge Problem: f'(x) = f(x) for all x in Q

    That's the conclusion I reached as well, but I figured that it was too simple of an answer to a challenge problem..
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    Solution to Challenge Problem: f'(x) = f(x) for all x in Q

    Sure: http://www.math.harvard.edu/~tomc/math25a/challenge.pdf It's from a class held Spring 2005. There are other challenge problems posted on the course webpage which are interesting as well.
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    Solution to Challenge Problem: f'(x) = f(x) for all x in Q

    This isn't a homework question or anything, but I came across this challenge problem posted on a Harvard Math 25a webpage and I'm wondering what the solution to it is since no solution is posted on the page. Suppose that f\colon \mathbb{Q} \to \mathbb{Q} satisfies f'(x) = f(x) for all x \in...
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    S_n acting on a set with more than n elements

    It acts on itself by conjugation, right? Does that action apply to sets with less than n! elements as well by taking an element a in the finite set and multiplying it by pap^{-1}?
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    All eigenvalues 0 implies nilpotent

    My point is that if the vector space is over the reals, for example, not every characteristic polynomial has roots (e.g. x^2+1), so if T^m(V) isn't over an algebraically closed field, we don't necessarily have that the restricted map has an eigenvalue...right?
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    S_n acting on a set with more than n elements

    So, essentially, S_n can act on any set of more than n elements by just permuting n of the elements and leaving the rest alone?
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    All eigenvalues 0 implies nilpotent

    Why must the restricted map have an eigenvector? I know where to go from there, but I can't seem to understand why that must be true since there isn't any assumption made that the base field of the vector space V is algebraically closed.
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