127,903 reputation
9121250
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 49
visits member for 2 years, 5 months
seen 2 hours ago

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


Feb
15
comment Is a map linear?
Hint: $(f+g)'=f'+g'$
Feb
15
comment The group $O(n)$ is contained in a sphere of radius $n$.
No, you're not.
Feb
15
comment How find this maximum $f(x)=\sqrt{\frac{1+x^2}{2}}+\sqrt{x}-x$
What do you mean with "But I can't prove it"?
Feb
15
comment Choosing points uniformly on a sphere surface
What is meant with "all" pairs, by the way?
Feb
15
comment Choosing points uniformly on a sphere surface
@Neal That doesn't look liek an exact solution
Feb
15
comment The distance between two sets inside euclidean space
What's dry about it?
Feb
15
answered Equality with mins headache
Feb
15
comment What's the intuition behind Pythagoras' theorem?
Property 4 is not needed. It holds for rectangles by 3 and for the rest of the world as a consequence. In fact 3 is needed only for a specific rectangle as the rest follows from 1 and 2 - a standard exercise when Lebesgue measuer is introduced, i.e. a translation-invariant (1) measure (2, for the restricted application to polygons here).
Feb
15
answered Why not define the Conway base-5 function, instead of base-13?
Feb
15
answered The distance between two sets inside euclidean space
Feb
15
answered Notation of this set in a set?
Feb
15
answered Show that finitely many disjoint discs can be inscribed in a unit square with total area approaching 1
Feb
15
reviewed Close Permutations using coefficient method
Feb
15
reviewed Close continuity of a function from the plane to the plane
Feb
15
answered region between two concentric circles are not convex set in eucledian space of order 2.
Feb
15
revised Is every countable graph spatial?
deleted 1 characters in body
Feb
15
revised Is every countable graph spatial?
added 530 characters in body
Feb
15
answered Is every countable graph spatial?
Feb
14
comment Polynomials/Function family that remains within interval bounds
$x\mapsto \sin(n\arcsin x)$ works for $[-1,1]\to[-1,1]$
Feb
14
comment Conjugate element
@Gyt because the inverse of the inverse is the element itself (and because some elements are note their own inverses)