123,631 reputation
8117239
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 48
visits member for 2 years, 3 months
seen yesterday

I did study math and had a knack for it, but I am sooo out of that business now ...


1d
comment Construct quadrangle with given angles and perpendicular diagonals
@Narasimham Yes, the solution is unique up to similarity, though this is not immediate from the IVT proof (but the transformation described changes the angles at $P$ monotonically)
1d
comment Construct quadrangle with given angles and perpendicular diagonals
A very interesting twist on the problem statement!
1d
comment What's the definition of a “local property”?
I suggest to dig especially into the differences between connected, locally connected, semilocally connected. Which if these is local?
1d
comment How is a part of eulerian path called?
Not every path that visits an edge at most once is necessarily a part of an Eulerian path
1d
comment $G$ is an open subset of $ \mathbb R$ such that $ 0 \notin G $ $ \implies$ {$xy | x , y \in G$ } is open?
@Nishant Therer is none. It's really just the fact that the union of open sets is open, and - if one does not like the word homeomorphism - division by $y\ne0$ is continuous, hence $Gy$, being the inverse image of the open set $G$ under a continuous map, is open.
2d
comment Prove there exist an isomorphism
I assume $V$ is a vector space over some field $k$ and $U$ is ...?
2d
comment Define a bijection function
or $9$, depending on your $\mathbb N$.
2d
answered Recursion. I don't understand proof.
2d
awarded  Caucus
2d
reviewed Close Extensions on matrix factorization
2d
reviewed Close How to select the right books?
2d
reviewed Close How to do sampling for the following problem.
2d
reviewed Close What kind of an optimisation problem am I dealing with?
2d
reviewed Close maximal ideal problem
2d
reviewed Leave Closed if (a,b) = 1 then ab-a-b=na+mb has no natural solution.
2d
comment maximal ideal problem
A maximal ideal in which ring? Certainly not in $K[x_1,\ldots,x_n,x_{n+1}]$
2d
reviewed Approve can the empty set be an element of a group?
2d
reviewed Approve Proving that each compact operator is bounded
2d
comment Selecting n matches from two pockets.
Check the case $n=1$
2d
answered Why Zariski topology is not Hausdorff