On the coordinatization of oriented matroidsDiscrete & Computational Geometry - Tập 1 - Trang 293-306 - 1986
Jürgen Bokowski, Bernd Sturmfels
Several important and hard realizability problems of combinatorial geometry can be reduced to the realizability problem of oriented matroids. In this paper we describe a method to find a coordinatization for a large class of realizable cases. This algorithm has been used successfully to decide several geometric realizability problems. It is shown that all realizations found by our algorithm fulfil...... hiện toàn bộ
k-Sets in Four DimensionsDiscrete & Computational Geometry - Tập 35 - Trang 177-191 - 2005
Jiri Matousek, Micha Sharir, Shakhar Smorodinsky, Uli Wagner
We show, with an elementary proof, that the number of halving simplices
in a set of n points in ℝ4 in general position is
O(n4-2/45). This improves the previous bound of
O(n4-1/13^{4}). Our main new ingredient is a bound on the maximum number of halving simplices intersecting a fixed 2-plane.
Densest packings of typical convex sets are not lattice-likeDiscrete & Computational Geometry - Tập 14 - Trang 1-8 - 1995
G. Fejes Tóth
We show that ifP is a convex polygon which has no parallel sides, then the densest packing of the plane with congruent copies ofP is not lattice-like. As a corollary we obtain that, in the sense of Baire categories, for most convex disks densest packing is not lattice-like.
Continuous and Discrete Radius Functions on Voronoi Tessellations and Delaunay MosaicsDiscrete & Computational Geometry - Tập 67 - Trang 811-842 - 2022
Ranita Biswas, Sebastiano Cultrera di Montesano, Herbert Edelsbrunner, Morteza Saghafian
The Voronoi tessellation in
$${{{\mathbb {R}}}}^d$$
is defined by locally minimizing the power distance to given weighted points. Symmetrically, the Delaunay mosaic can be defined by locally maximizing the negative power distance to other such points. We prove that the average of the two piecewise...... hiện toàn bộ
Asymptotics for Some Combinatorial Characteristics of the Convex Hull of a Poisson Point Process in the Clifford TorusDiscrete & Computational Geometry - Tập 49 Số 2 - Trang 200-220 - 2013
Magazinov, Alexander
Let $$\mathcal P _\lambda $$ be a homogeneous Poisson point process of rate $$\lambda $$ in the Clifford torus $$T^2\subset \mathbb E ^4$$ . Let $$(f_0, f_1, f_2, f_3)$$ be the $$f$$ -vector of conv $$\,\mathcal P _\lambda $$ and let $$\bar{v}$$ be the mean valence of a vertex of the convex hull. Asymptotic expressions for $$\mathsf E \, f_1$$ , $$\mathsf E \, f_2$$ , $$\mathsf E \, f_3$$ and $$\m...... hiện toàn bộ
A Partitioned Version of the Erdös–Szekeres Theorem for QuadrilateralsDiscrete & Computational Geometry - Tập 30 - Trang 321-336 - 2003
Attila Póor
We prove a partitioned version of the Erdös–Szekeres theorem for the case
$k = 4$: any finite set $X \subset \bbbr^2$ of points in general position
can be
partitioned into sets $X_0, X_{ij}$ where $i=1,2,3,4$ and $j=1,\ldots,26$,
so that $|X_{1j}|=|X_{2j}|=|X_{3j}|=|X_{4j}|$, $|X_0|\leq 4$ and for all $j$
every transversal $\{x_1,x_2,x_3,x_4\}$,
$x_1 \in X_{1j}, x_2 \in X_{2j},x_3 \in X_{3j}, x_4...... hiện toàn bộ
Minimising the Sum of Projections of a Finite SetDiscrete & Computational Geometry - Tập 60 - Trang 493-511 - 2018
Vsevolod F. Lev, Misha Rudnev
Consider the projections of a finite set
$$A\subset {\mathbb R}^n$$
onto the coordinate hyperplanes; how small can the sum of the sizes of these projections be, given the size of A? In a different form, this problem has been studied earlier in th...... hiện toàn bộ