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1d
answered Is there such splitting?
1d
answered Families of Idempotent $3\times 3$ Matrices
Aug
21
answered Whether two quotients of $\mathbb{Z}^2$ are isomorphic.
Aug
19
answered Tightenning Interval Mapping
Aug
15
answered If a polynomial has only real zeros then $a_{0}+a_{1}+\cdots+a_{n}\le\frac{(n+1)^n}{\binom{n}{s}(n-s)^{n-s}(s+1)^s}\cdot\max_{k}a_{k}$
Aug
15
asked A “repeated roots allowed” version of the continuity of roots
Aug
15
answered Determining if a recursively defined sequence converges and finding its limit
Aug
14
answered How prove that $q \geq b+d$ for $ad-bc = 1$ and $\frac{a}{b} > \frac{p}{q} > \frac{c}{d}$?
Aug
13
answered if $ax-2by+cz=0$ and $ac-b^2>0$ , Prove $zx-y^2\leq0$
Aug
12
answered How to find a nonlinear function $f:\mathbb{R}^2\to\mathbb{R}^2$ that is almost linear in the sense $f(\alpha (a,b))=\alpha f(a,b)$?
Aug
12
asked Representation of integers by ternary quadratic form $x^2+y^2-z^2$
Aug
6
asked Every endomorphims is a linear combination of how many idempotents in infinite dimensions?
Aug
3
answered show that there are $1\leq j_1< j_2< j_3\leq 13$ such that $\left | A_{j1}\cap A_{j2}\cap A_{j3} \right |\geq 3$.
Aug
2
answered Find continuous $f$ s.t. $f(x,y)^2 = x^2$ ($f: H \to \mathbb{R}$, H connected)
Jul
28
answered Showing an indentity with a cyclic sum
Jul
27
asked Always “one double root” between “no root” and “at least one root” ? (Second version)
Jul
27
answered Surprising necessary condition for a “shift-invariant” determinant
Jul
27
asked Always a double root between “no roots” and “at least one root”?
Jul
26
answered A Sperner type problem on infinite antichains
Jul
24
answered Prove that: $\sum \frac{a^2+2bc}{(b+c)^2}\geq \sum \frac{3}{2}\frac{a}{b+c}$