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Euclidean, hyperbolic, discrete, convex, coarse geometry, metric spaces, comparisons in Riemannian geometry, symmetric spaces.
0
votes
Most dispersed set of points in a disk?
Maybe not an exact answer, but some thoughts to get a foot in the door:
no three points must be collinear, because otherwise a triangle with area $0$ would exist and thus every set of points in ge …
0
votes
Most dispersed set of points in a disk?
A more practical heuristic for generating dispersed point sets inside a compact region $\Omega$, that also generates to higher dimensions is the following, which I would like to call the stay away fr …
2
votes
0
answers
104
views
Area of an intersection of three ellipses
Let $\Delta := (A,B,C)$ be a triangle that is defined by three points in the Euclidean plane that are not collinear.
Let further $E_{(A,B),\,C},\,E_{(C,A),\,B},\,E_{(B,A),\,B}$ be the set of ellipses …
6
votes
What shapes can be gears?
if you look for non-circular gear you at least find the wiki article that also addresses the mathematics; there are also links to publication on the subject.
1
vote
2
answers
128
views
An optimality condition for the corners of convex polytopes?
Let $H,H'\subset\mathbb{R}^m$ be two hyperplanes with unit normal-vector,
and let $P\subset\mathbb{R^m}$ be a convex polytope (defined via its corners $v_0, ... , v_n$, where $n\ge m$).
Let's furth …
0
votes
An optimality condition for the corners of convex polytopes?
It just occured to me that the question can be answered in the affirmative way for the following reasons:
the order relation doesn't change if the distance sum is divided by some positive constant …
5
votes
How can you compute the maximum volume of an envelope(used to enclose a letter)?
As the envelope is made of paper, a mathematical model of its deformation would be an isometric coordinate transformation and thus must have zero Gauss curvature almost everywhere; that restriction is …
2
votes
0
answers
36
views
Is there a "last mile" criterion for a generalization of planar convex hulls to symmetric we...
This question is motivated by an almost successful attempt to define planar convex hulls of a finite set of isolated points only via subset sums of the distances between point-pairs; the advantage of …
1
vote
0
answers
27
views
Finding most Representative Sample in "Pair Statistics"
By "Pair Statistics" I understand statics that are based on values $\varphi:\mathcal{P}\times\mathcal{P}\ni(p,q)\mapsto y\in\mathbb{R}$ that can be observed for every pair $(p,q)$ of individuals of a …
1
vote
1
answer
38
views
Is this relation between planar convex hulls and heaviest cliques true?
If $P$ is a set of $n$ points in the euclidean plane whose convex hull $\operatorname{CH}(P)$ has $h$ corners, and $Q\subset P$ has $m\le\lfloor\frac{h}{2}\rfloor$ points and maximal sum of pairwise d …
3
votes
1
answer
188
views
Deflating a tetrahedron to a $K_4$ graph with equal changes to sidelengths
Let $A,B,C,D$ be the corners of a tetrahedron with positive volume and distinct sidelengths. Is there a positive $x$ and a planar straight-line embedding of a $K_4$ graph with distinct vertices $A’,B’ …
1
vote
closest equidistant point to N points in M dimensions
An algorithm that works at least for dimensions $2$ and $3$ is:
calculate a spanning tree of the $n$ points
calculate the bisector planes of the spanning tree's edges
the sought poiint is in the inte …
1
vote
Characterization of greedy TSPs?
A simple "a posteriori" criterion is that on the optimal tour the distances to the tour-neighbors is smaller than that to any of the other vertices.
Convexity alone doesn't suffice as the example of e …
3
votes
Equitably distributed curve on a sphere
to me the best possible solution seems to be the sequence of closed Hilbert curves on the Cubed Sphere;
that curve consists of six ordinary Hilbert Curves, one for each face of a cube, which, when app …
1
vote
0
answers
211
views
Quadrilaterals from a Unit Stick
This question could be seen as a coordinate-free variant of Sylvester's Four Point Problem (cf e.g. http://mathworld.wolfram.com/SylvestersFour-PointProblem.html):
Suppose one are given an inifinit …