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martini's user avatar
martini's user avatar
martini
  • Member for 12 years, 10 months
  • Last seen more than 1 year ago
160 votes
Accepted

Poisson Distribution of sum of two random independent variables $X$, $Y$

60 votes

How the product of two integrals is iterated integral? $\int\cdot \int = \iint$

58 votes
Accepted

Find $x$ such that $\sqrt{x+\sqrt{x+7}}\in \mathbb{N}$

53 votes
Accepted

Dual of $l^\infty$ is not $l^1$

52 votes

Sum of two independent binomial variables

48 votes
Accepted

Are weak derivatives and distributional derivatives different?

42 votes
Accepted

Is trace invariant under cyclic permutation with rectangular matrices?

42 votes
Accepted

Splitting of conjugacy class in alternating group

40 votes

If $x$, $y$, $x+y$, and $x-y$ are prime numbers, what is their sum?

33 votes

If there are injective homomorphisms between two groups in both directions, are they isomorphic?

31 votes
Accepted

Why is the operator $2$-norm of a diagonal matrix its largest value?

28 votes
Accepted

When does the inverse of a covariance matrix exist?

27 votes
Accepted

Definition of the total variation distance: $ V(P,Q) = \frac{1}{2} \int |p-q|d\nu$?

26 votes
Accepted

Is there a way to calculate absurdly high powers?

25 votes

Derivative of the inverse of a matrix

23 votes
Accepted

Complex vs. Real Differentiable

20 votes
Accepted

Can a differential equation have non unique solutions?

20 votes
Accepted

Is the sum of singular and nonsingular matrix always a nonsingular matrix?

20 votes
Accepted

About the Cantor-Schroeder-Bernstein theorem.

19 votes

Why is interchanging the order of limits in this situation equivalent to asking for continuity?

19 votes
Accepted

A closed subspace of a reflexive Banach space is reflexive

19 votes
Accepted

Can we always multiply some function that is not differentiable everywhere with function that is to obtain differentiable product?

18 votes
Accepted

Convergence in weak topology implies convergence in norm topology

18 votes
Accepted

Inductive Proof for Vandermonde's Identity?

18 votes

Proving the relation $\det(I + xy^T ) = 1 + x^Ty$

17 votes

approximating a maximum function by a differentiable function

17 votes

Why does a Lipschitz function $f:\mathbb{R}^d\to\mathbb{R}^d$ map measure zero sets to measure zero sets?

17 votes
Accepted

Showing the basis of a Hilbert Space have the same cardinality

16 votes
Accepted

Father and daughter river crossing puzzle.

16 votes
Accepted

Continuous extensions of continuous functions on dense subspaces

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