Search Results
Search type | Search syntax |
---|---|
Tags | [tag] |
Exact | "words here" |
Author |
user:1234 user:me (yours) |
Score |
score:3 (3+) score:0 (none) |
Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
Views | views:250 |
Code | code:"if (foo != bar)" |
Sections |
title:apples body:"apples oranges" |
URL | url:"*.example.com" |
Saves | in:saves |
Status |
closed:yes duplicate:no migrated:no wiki:no |
Types |
is:question is:answer |
Exclude |
-[tag] -apples |
For more details on advanced search visit our help page |
A branch of geometry dealing with convex sets and functions. Polytopes, convex bodies, discrete geometry, linear programming, antimatroids, ...
3
votes
Isodiametric hull
This isodiametric hull is not well defined. The first observation is that any curve of constant width is its own isodiametric hull. Now let's take an isosceles triangle ABC with $\angle A=20^{\circ}$, …
4
votes
Accepted
Realisation of convex polygons with an interior point from combinatorial data
Given $e$ so that it satisfies your condition of distinct triangles intersecting nontrivially we will prove that it comes from an associated polygon by induction on the number of vertices of the polyg …
5
votes
Tetrahedron angles sum to $\pi$: Bisector plane
This is still in terms of trigonometry, but it's pretty quick. Let $\vec{u}$ and $\vec{v}$ be the unit vectors in the direction of $\vec{bc}$ and $\vec{ba}$, respectively. We have
$$\angle dba + \angl …
28
votes
Accepted
Largest possible volume of the convex hull of a curve of unit length
I believe this problem has been mentioned a few times in the literature, and has been solved for certain restrictions on the curve. For example if the curve has no four coplanar points then the maxima …
4
votes
Accepted
Polar interpretation of convexity
Convexity is equivalent to the function $r(\theta):[0,2\pi)\to\mathbb{R}^2$ being well-defined and satisfying the condition
$$| r(\lambda \theta _1+(1-\lambda)\theta _2)| \geq \left| \lambda r(\theta …
6
votes
Accepted
Number of orthants intersected by a convex hull
Consider the $k-1$ dimensional simplex given by $\alpha_1+\alpha_2+\cdots \alpha_k=1, \alpha_i\geq 0$. The equations $e_i\cdot (\sum_{j=1}^k \alpha_j x_j)=0$ for $1\le i\le n$ describe $n$ hyperplanes …
5
votes
Accepted
Are cyclic orbitopes of permutahedra necessarily simplicies?
Let $M$ be the circulant matrix whose rows are given by cyclic shifts of $(v_1,\dots v_d)$ and let $P(x)=v_1+v_2x+\cdots+v_dx^{d-1}$ be the associated polynomial. Moreover, let $s$ be the degree of $\ …