Skip to main content
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
Results tagged with
Search options not deleted user 172802

A branch of geometry dealing with convex sets and functions. Polytopes, convex bodies, discrete geometry, linear programming, antimatroids, ...

5 votes
Accepted

Center of convex figure

There does not exist any function $p:F\mapsto p_F$ as in the question, to prove it by contradiction suppose such a function $p$ exists. In the following let $k+A=\{k+a;a\in A\}$ for any $k\in\mathbb{R …
Saúl RM's user avatar
  • 10.6k
5 votes
Accepted

Does the surface area of the unit Lp ball go to zero for all $p < \infty$?

The surface area of the unit $L^p$ ball (of radius $1$) goes to $0$ as $n$ goes to infinity, if $p<\infty$. Below I show it for $p>2$, but this is enough because if we have convex sets $A\subseteq B$, …
Saúl RM's user avatar
  • 10.6k
5 votes
Accepted

Estimating shortest paths in planar drawings of graphs

Here are triangulations of a side $1$ square with vertices at a arbitrarily high distance of all the four vertices of the square. The sides of the side $1$ square are not edges but it is easy to see t …
Saúl RM's user avatar
  • 10.6k
5 votes

Convex set with no interior contained in hyperplane?

Here is an example of a convex subset $X$ of an infinite-dimensional separable Hilbert space $H$ with empty interior and which is not contained in any hyperplane of $H$, closed or not. Let $(v_i)_{i\i …
Saúl RM's user avatar
  • 10.6k
4 votes

Pushing a convex cone and equidistants

$K_t$ need not be a translate of $K$. Let $A=[-4,4]\times[-1,1]\subseteq\mathbb{R}^2$ and consider the convex cone $K=\{t\cdot v;t\in[0,\infty),v\in A\times\{1\}\}\subseteq\mathbb{R}^3$. Note that $\p …
Saúl RM's user avatar
  • 10.6k
2 votes
Accepted

Existence of fine approximate of a convex body in $\mathbb R^d$ with convex hull of $\mathca...

This is false for any fixed $\theta\in(\frac{1}{2},1)$, we will use the balls of radius $1$ in $\mathbb{R}^d$ as a counterexample. Given $\theta$, if we want $ \theta K \subseteq \operatorname{conv}\{ …
Saúl RM's user avatar
  • 10.6k
1 vote
Accepted

On the Lipschitz continuity of $x \mapsto \arg\min_{c \in C}d(x,c)$ w.r.t Hausdorff distance

Seems like in fact convex sets are the only ones for which $p_C$ is continuous. To prove this, we can begin by noticing that for a set $C$ with the property, $p_C$ can only take one point sets as valu …
Saúl RM's user avatar
  • 10.6k
1 vote
Accepted

Maximum number of vectors with bounds on inner products (follow up question)

This is not an answer to the question, but here are some upper/lower bounds. Firstly, if we let $A_i\subseteq\{0,1,\dots,k+1\}$ be the non zero coordinates of $m_i$, then we can't have $A_i\subseteq A …
Saúl RM's user avatar
  • 10.6k