Recent content by masnevets

  1. M

    Happy holidays,BenDecomposing tensor product of GL(2,C) representations

    Hi, To decompose a tensor product of representations of GL(n,C) into a direct sum of irreps, use the Littlewood-Richardson rule: http://en.wikipedia.org/wiki/Littlewood–Richardson_rule In your case, C^2 is the standard representation represented by the partition (1), and Sym^{N-2}(C^2) is...
  2. M

    Infinitely Many Primes: Proofs & Homological Algebra

    Hi all, I am for some reason interested in creative or weird proofs of the fact that there are infinitely many prime numbers. I have started writing down all of the proofs that seemed sufficiently different in the following file: http://www.ocf.berkeley.edu/~ssam/primes.pdf If you know...
  3. M

    Completeness of irreducible representations

    This is certainly not enough. You need to know that the representation is irreducible because for the trivial representation, we can just have all the entries mapping into a 2x2 identity matrix, and then the 01 entry of each matrix is 0. I don't know the answer yet, but I'll think about it...
  4. M

    Schools Realistic Grad Programs for Math Students Starting at Community College?

    I sent you a reply to the e-mail, so I look forward to meeting you tomorrow. But I'll say a few quick words about your post: EDIT: Actually, I had something here, but maybe I'd rather not say anything about people on the internet. Let's save it for in person. :)
  5. M

    Schools Realistic Grad Programs for Math Students Starting at Community College?

    Hi, I'm also a UC Berkeley math major. I'm finishing this semester and now I am in the fun/stressful stage of visiting grad schools and ultimately trying to decide where to go. I know of a guy from a few years ago who transferred in from a community college and then went on to Princeton...
  6. M

    Studying Why maths textbooks when you can have Wikipedia?

    Wikipedia is definitely not anywhere close to the amount of knowledge contained in math textbooks.
  7. M

    Graduate School Application Results and Strategies - Fall 2008

    Most math departments don't like the general GRE, but it is a requirement for university admissions. From my understanding, most departments don't care much for the subject GRE score--if you do well, it won't help you, but if you do poorly, it raises a flag. I think it's particularly important...
  8. M

    Graduate School Application Results and Strategies - Fall 2008

    I don't think it matters that you've completed a masters first.
  9. M

    Graduate School Application Results and Strategies - Fall 2008

    Right, sorry I applied to seven schools. I really had no idea that any of those three schools would accept me. I was told by my advisor that I had a good shot, but that when it comes down to the final decisions, it's all a crapshoot. So I was basically told to apply to the "big 5" (Berkeley...
  10. M

    Graduate School Application Results and Strategies - Fall 2008

    It's because American universities can be very fickle. There are no sure things. For example, I've been admitted to Princeton and MIT but got rejected from Harvard, whereas a friend of mine received the opposite treatment (accepted to Harvard but rejected from the other two).
  11. M

    Are the Sum of Two Functions Always Equal to the Sum of their Individual Parts?

    that's a definition as far as I am concerned. How are you defining (f+g)(x)?
  12. M

    A Combinatorial Proof for (n choose 2) choose 2 = 3(n choose 4) + 3(n choose 3)

    Well the left hand side \binom{\binom{n}{2}}{2} counts the number of unordered pairs of unordered pairs. What exactly can one look like? Either it involves 4 distinct elements, or it involves 3 distinct elements, like {{a,b}, {a,c}}, but it can never involve 2 or 1 distinct elements (why)? I...
  13. M

    Showing a mapping is onto and/or one to one

    I am exploiting linearity, yes. As mentioned above, to check that a map is injective in general, one needs to show that if f(x) = f(y), then x=y. But in the case of a linear map, f(x) = f(y) implies f(x-y) = 0, so you only need to check the case that something maps to zero. For onto, you can...
  14. M

    Showing a mapping is onto and/or one to one

    To show that a map is injective (one-to-one), you take some element x that maps to 0, and then prove that x has to be 0. So in your case, pick some x and y such that f(x,y) = 0. Then x-2y=0 and x+y =0. Since x=-y, the first equation becomes -3y=0, and so x=y=0.
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