18
votes
Help deriving that $\mathrm{sign} : S_n\to \{\pm 1\}$ is multiplicative
group-theory
permutations
determinant
symmetric-groups
multilinear-algebra
asked Nov 8, 2011 at 0:52
math.stackexchange.com
17
votes
If $z_n \to z$ then $(1+z_n/n)^n \to e^z$
real-analysis
complex-analysis
limits
exponential-function
asked Apr 28, 2013 at 0:13
math.stackexchange.com
16
votes
Compact = Closed + Bounded + (?)
real-analysis
soft-question
asked Nov 25, 2011 at 18:41
math.stackexchange.com
16
votes
Limit of integration can't be the same as variable of integration?
calculus
notation
asked Feb 14, 2012 at 0:13
math.stackexchange.com
15
votes
Why can't there be a monotone function with domain $\mathbb{R}$ and range $\mathbb{R} \setminus \mathbb{Q}$?
real-analysis
asked Oct 26, 2011 at 0:57
math.stackexchange.com
15
votes
Positivity of principal eigenvalue for $L\phi=-\triangle \phi + \nabla \cdot( u \phi )$
pde
eigenfunctions
asked Apr 10, 2014 at 17:16
math.stackexchange.com
15
votes
Solve a PDE on a domain $\Omega$ with given boundary conditions
differential-equations
asked Oct 24, 2013 at 16:06
mathematica.stackexchange.com
15
votes
Interpretation of eigenvectors of Hessian in context of local min/max/saddle?
calculus
multivariable-calculus
optimization
stationary-point
asked Nov 8, 2015 at 18:09
math.stackexchange.com
15
votes
Is there a countable cover of $\mathbb{R}^2$ by balls $B(x_n, n^{-1/2})$?
real-analysis
measure-theory
real-numbers
asked Nov 11, 2015 at 1:45
math.stackexchange.com
14
votes
Prove the normed space of bounded variation functions is complete
real-analysis
banach-spaces
bounded-variation
asked Oct 17, 2011 at 22:20
math.stackexchange.com
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