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A generalized permutohedron as the sum of the dilatations of the faces of the standard simplex

I am trying to understand the proof of the statement, specifically it refers to a theorem stated by Postnikov in his text on permutohedra. So, this sentence claims the following: If $\{Y_I \}$ is a ...
Wrloord's user avatar
  • 251
3 votes
1 answer
111 views

Does a matroid base polytope contain its circumcenter?

Let $(X,\mathcal B)$ be a matroid on the ground set $X=(x_1,...,x_n)$ and with set of bases $\mathcal B$, and let $P\subset\Bbb R^n$ be its matroid base polytope (i.e. the convex hull of the ...
M. Winter's user avatar
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6 votes
2 answers
291 views

"Minimal" connected matroids

I'm interested in connected matroids $M$ on the ground set $[n]$ for which there is no connected matroid on $[n]$ of the same rank but with a strictly smaller set of bases (by inclusion). Equivalently,...
Igor Makhlin's user avatar
  • 3,513
8 votes
2 answers
209 views

Constructing a $0/1$ polytope from an abstract simplicial complex

Let us fix $\Delta$ a finite simplicial complex, and label the vertices of $\Delta$ as $\{1,2,\ldots,n\}$. For each $F\in \Delta$ let us consider the point in $\mathbb{R}^n$ given by: $$e_F := \sum_{i\...
Luis Ferroni's user avatar
  • 1,889
3 votes
1 answer
409 views

Looking for a canonical (matroid polytope) subdivision of the hypersimplex

A matroid polytope is the convex hull of the indicator vectors of the bases of a matroid, and a matroid polytope subdivision (MPS) is a polyhedral subdivision of a matroid polytope whose cells are ...
Camilo Sarmiento's user avatar