Igor Rivin's user avatar
Igor Rivin's user avatar
Igor Rivin's user avatar
Igor Rivin
  • Member for 10 years, 3 months
  • Last seen more than a month ago
31 votes

If matrix A is invertible, is it diagonalizable as well?

15 votes
Accepted

Let $f: \mathbb{R} \to \mathbb{R}$ be continuous periodic function with period $T>0$

15 votes

A question on integration

13 votes
Accepted

What is a Kählerian variety?

12 votes
Accepted

Proof of Existence of Algebraic Closure: Too simple to be true?

11 votes
Accepted

Are there odd-sheeted coverings of non-orientable surfaces by orientable surfaces?

11 votes

Evaluating the primitive $\int \frac{\mathrm dx}{e^{2x} + e^x + 1} $

11 votes

Why is $x\log(x)$ convex?

9 votes

Analytic number theory books after Apostol

9 votes
Accepted

Introductive Book on Modular Forms

9 votes

Show the following: $\displaystyle\sum_{n=1}^\infty\dfrac1{n(n+k)}=\dfrac{H_k}k$.

9 votes

Find a polynomial with integer coefficients

8 votes

$3$ does not divide $|G| \implies \forall \ g \in G, g=h^3$ , for some $h$ in $G$

8 votes
Accepted

Evaluating $\int_{0}^{1} \frac{x^{2n+2}}{x^2-2x+2}\,{\rm d}x$

8 votes

The $i$-th center $Z_{i}(G)$

8 votes

Which is larger :: $y!$ or $x^y$, for numbers $x,y$.

8 votes

Prove that there are no such different positive numbers that satisfy both $a+b=c+d$ and $a^3+b^3=c^3+d^3$.

8 votes

subgroups of the centers of a group are all normal

8 votes
Accepted

Fundamental Group Two Tori

8 votes
Accepted

Show that there are no onto homomorphisms from $\mathbb{Z}_{18}$ to $S_3$

8 votes
Accepted

Are there groups $G$, whose order is uncountable, such that the order of $G/[G,G]$ is countable?

7 votes

Finding determinant for a matrix with one value on the diagonal and another everywhere else

7 votes
Accepted

all prime numbers have irrational square roots

7 votes
Accepted

How to show that $\Delta\left(\frac{az+b}{cz+d}\right)=(cz+d)^{12}\Delta(z)$?

7 votes
Accepted

How to express a matrix as a product of two symmetric matrices?

7 votes

A real life application for QR decomposition

7 votes

Proving $(A+B)^{-1} = A^{-1} + B^{-1}$ when there exists $J$ so that $J^2 = -I$

7 votes
Accepted

Injectivity of a function of several variables

6 votes

Representing all rational numbers between $\dfrac{1}{2}$ and $1$

6 votes

Proving limit of an iterative sequence

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