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Apr
10
comment A reference for a combinatorial identity
The second form looks like just a Vandermonde's identity ($\binom{i+k-1}i=\pm\binom{-k}i$ etc).
Apr
8
comment Stiefel-Whitney classes with Z-coefficients
(Re: The only problem I see is with the Steenrod square operation which may be undefined for integral coefficients) Well, yes there are no non-trivial stable operations from H(-;Q) to H(-;Q), after all...
Apr
7
reviewed Close Arrange white and colored balls in cells
Apr
7
reviewed Close Simplifying $\arctan\left(\frac{1}{\tan \alpha}\right)$
Apr
6
reviewed Leave Open Every prime is maximal in a Jacobson ring?
Apr
6
reviewed Close Riemann integrable functions-True or False
Apr
6
reviewed Close $\frac{1}{2}!$ aka $\Gamma(\frac{3}{2})$
Apr
5
reviewed Close Find $\lim_{x\to 0} \frac{\sin\left((2t+1)x\right)}{(t+1)x}$
Apr
5
reviewed Close How can i integrate the equation below and simplify exp(e^t)?
Apr
5
reviewed Close finding all singularities of $f(z)= (z \sin z ) / (1-\cos z)$
Apr
5
reviewed Close Can modulo(remainder) be distribute over division?
Apr
5
reviewed Leave Open Evaluating $ \sum_{n=1}^\infty \frac{1}{n^2 2^n} $
Apr
5
reviewed Close Algebra: Integral extension
Apr
5
reviewed Close Commutative algebra: Integral extension
Apr
5
reviewed Close Prove that $1+20^1+20^2+\cdots+20^{21}\equiv 0\pmod{23}$
Apr
5
reviewed Close Floor and Ceiling Proofs
Apr
5
reviewed Leave Closed Projection of a Jinc is a Sinc
Apr
5
reviewed Close If 12 identical balls are to be placed in 3 identical boxes, then the prob that one of boxes contains exactly 3 balls is?
Apr
5
reviewed Leave Open Proving real polynomials of degree greater than or equal to 3 are reducible
Apr
5
reviewed Leave Open Examples of functors that preserves products but not equalizers, and vice versa.