109,501 reputation
698199
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 48
visits member for 1 year, 11 months
seen yesterday

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


Aug
20
comment Notation for mimimal sum when choosing elements from two sets
There is no special notation for this, I'm afraid, and the minimum is quite clearly $\sum_{i\in I}\min\{s_i,t_i\}$, isnt't it?
Aug
20
reviewed Edit Evaluating the limits $\lim_{(x,y)\to(\infty,\infty)}\frac{2x-y}{x^2-xy+y^2}$ and $\lim_{(x,y)\to(\infty,8)}(1+\frac{1}{3x})^\frac{x^2}{x+y}$
Aug
20
revised Evaluating the limits $\lim_{(x,y)\to(\infty,\infty)}\frac{2x-y}{x^2-xy+y^2}$ and $\lim_{(x,y)\to(\infty,8)}(1+\frac{1}{3x})^\frac{x^2}{x+y}$
added 17 characters in body; edited title
Aug
20
reviewed Edit General form for $2\int_{0}^{\infty} \frac{1-t^2}{(1+t^2)((a+b)t^2+a-b)} \mathrm dt$
Aug
20
revised General form for $2\int_{0}^{\infty} \frac{1-t^2}{(1+t^2)((a+b)t^2+a-b)} \mathrm dt$
Maybe this makes sense ...
Aug
20
reviewed Close In how many ways can a number be expressed as a sum of squares of two natural numbers?
Aug
20
reviewed Close What is the space spanned by $a\cos x + b\sin x$?
Aug
20
reviewed Leave Open Find x in this equation
Aug
20
answered Combining independent predictions into an overall probability
Aug
20
comment Combining independent predictions into an overall probability
The main problem is: Different predictions are hardly independant. If you ask one hundred amateur meteorologists, each of whom is right 70% of the time, and they all say tomorrow will be rainy, should that make us confident way above 70% that it will rain? No: Maybe they all know that 70% of the time tomorrow is the same wheather as today and based they prediction on the observation that it rains today ...
Aug
20
comment How prove this sequence $u_{m}=v_{m}$
Write down the first few $u_k$ and see if you find a pattern
Aug
20
comment Do full-rank linear transformations preserve strong convexity?
Is $m$ fixed, depending only on $g$, or depending on $x,y$? And is the domain finite-dimensional?
Aug
20
awarded  Nice Answer
Aug
19
comment Algorithm for finding contradictions in a directed graph that represents implications
Of course there is one, just walk through all arcs.
Aug
19
answered Is entire function constant when $ |f(z)|\le \log|z|,\ |z|>1$.
Aug
19
comment Is entire function constant when $ |f(z)|\le \log|z|,\ |z|>1$.
@helplessKirk What's needed and used, is $|z_n|>1$, and that's fine.
Aug
19
answered Is division allowed in rings and fields?
Aug
19
comment The Diophantine equation $x^p - 4y^p = z^2$ with $(x, y) = 1$ and $x, y, z > p.$
There's $5^3-4\cdot 1^3=11^2$ ...
Aug
19
reviewed Close Intuitive explanation for $\zeta (2)=\frac{\pi^2}{6}$
Aug
19
reviewed Leave Open interval of convergence of $e^x$