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age 44
visits member for 3 years, 3 months
seen Jun 23 at 10:19

Math professor at Cornell, PhD 1996.

I dabble in string theory, but haven't published anything physical in ages.


Jul
31
comment Isomorphic Dual and Conjugate Representations of a Lie Algebra
Check it once and for all for the Lie algebra $End(V)$ itself. I'm voting to close as not research-level.
Jun
11
comment Explanation for a line from a MathOverflow answer
Well, the key step is equivariant Kunneth, which I'm happy to apply if e.g. $H^*_S$ and $H^*_H$ are concentrated in even degree, e.g. if $S,H$ are connected. Without that I become squeamish about equivariant Kunneth.
Apr
13
comment Intuition? how the author reaches the answer?
Say $\vec w=(w_1,\ldots,w_8)$. Then declaring $x_2 x_4$ to be the initial term of $x_1 x_5 - x_2 x_4$, with respect to the $\vec w$ order, gives the linear inequality $w_2 + w_4 > w_1 + w_5$. In your first question, you need to decide which of the two terms in each binomial you want to be the leading term, in such a way that the resulting S-polynomials reduce to 0. But then you need to be sure that there is a term order that actually gives those choices of initial term. So find a $\vec w$ satisfying the three attendant linear inequalities.
Apr
11
answered Intuition? how the author reaches the answer?
Mar
15
comment Explanation for a line from a MathOverflow answer
I think it's a mistake to explicitly include $EG$ factors in one of these deeper calculations. Accept that $H_G(X) = H(X/G)$ for free actions and then black-box that away. Partly because, when you move beyond $H^*()$ to $K()$ you don't use the Borel construction any more.
Mar
14
awarded  Teacher
Mar
14
answered Explanation for a line from a MathOverflow answer
May
23
comment Partial sum over $M$, of ${m+j \choose M} {1-M \choose m+i-M}$?
${a\choose k} = a(a-1)\cdots (a-k+1)/k!$ for $k\geq 0$, so ${-n\choose k} = (-1)^k {k+n-1\choose k}$.
May
23
comment Partial sum over $M$, of ${m+j \choose M} {1-M \choose m+i-M}$?
Yes, and I did, but not enough to guess an answer. Examples added.
May
23
revised Partial sum over $M$, of ${m+j \choose M} {1-M \choose m+i-M}$?
added 3756 characters in body; added 25 characters in body
May
22
awarded  Editor
May
22
revised Partial sum of ${A \choose i} {B\choose n-i}$, when $B=-1$?
added 173 characters in body
May
22
asked Partial sum over $M$, of ${m+j \choose M} {1-M \choose m+i-M}$?
May
22
awarded  Student
May
22
asked Partial sum of ${A \choose i} {B\choose n-i}$, when $B=-1$?