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 Jan 2 reviewed Edit Complement of a tree $T$ Jan 2 revised Complement of a tree $T$ Added MathJax. Jan 2 answered Complement of a tree $T$ Dec 29 revised differential forms of 2 sphere edited tags Dec 25 reviewed Close Closed form for $\sum_{k=1}^n\frac{1}{(2k-1)(2k+1)}$ Dec 25 revised Show that if $\omega$ is a 1-form differential, then $\left\vert\int_{C}\omega\right\vert\leq ML$ edited tags Dec 25 answered Compact Manifold with Geodesic B0undary Dec 15 answered Integration of $\frac {1}{1+\sin x}$ Dec 15 reviewed No Action Needed Upper bound for a number of subsets of $\{1, \dots, n\}$ Dec 13 revised Euler-Lagrange equation of a functional edited tags Dec 13 answered system of equations when the matrix corresponding $\det(A)=\pm1$ has integers solution Dec 13 reviewed Approve Inversion of n x n matrix. Dec 4 reviewed Approve Converting differential equation $x''+\sin(x)= 0$ to a system of ODEs Dec 4 reviewed Reject An urn contains two red balls and four white balls. Sample successively five times at random and with replacement so that the trials are independent. Dec 4 reviewed Reject Find the joint PMF of X and Y, are they independent? Dec 4 reviewed Approve Does this series of functions converge? Nov 28 answered Symmetric Matrix Equation Nov 26 answered Relationship between Nullspaces Nov 13 comment Computing the integral of a differential form in $\mathbb{R}^{2}$. I think it would be easier to use polar coordinates $(r,\theta)$. Oct 27 comment Einstein manifolds and topology Yes. It really depends on your definition of Einstein manifold. You can define Einstein manifold to satisfy $Ric=kg$ for some constant $k$. Or you can define Einstein manifold to satisfy $Ric=\frac{R}{n}g$, or equivalently, the traceless Einstein tensor is zero. But they are equivalent by the Bianchi identity, at least for $n\geq 3$.