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A convex geometric graph $G$ is said to be packable if there exist edge-disjoint copies of $G$ in the complete convex geometric graph $K_n$ covering all but $o(n^2)$ edges. We prove that every convex geometric graph with cyclic chromatic…

Combinatorics · Mathematics 2024-02-27 Jiaxi Nie , Erlang Surya , Ji Zeng

Given a polygon $P$ in the plane, a {\em pop} operation is the reflection of a vertex with respect to the line through its adjacent vertices. We define a family of alternating polygons, and show that any polygon from this family cannot be…

Computational Geometry · Computer Science 2009-11-24 Adrian Dumitrescu , Evan Hilscher

We construct the first two continuous bloomings of all convex polyhedra. First, the source unfolding can be continuously bloomed. Second, any unfolding of a convex polyhedron can be refined (further cut, by a linear number of cuts) to have…

Computational Geometry · Computer Science 2009-06-16 Erik D. Demaine , Martin L. Demaine , Vi Hart , John Iacono , Stefan Langerman , Joseph O'Rourke

We study finite groups that occur as combinatorial automorphism groups or geometric symmetry groups of convex polytopes. When $\Gamma$ is a subgroup of the combinatorial automorphism group of a convex $d$-polytope, $d\geq 3$, then there…

Combinatorics · Mathematics 2019-07-29 Egon Schulte , Pablo Soberón , Gordon Ian Williams

We show that double cosets of the infinite symmetric group with respect to some special subgroups admit natural structures of semigroups. We interpret elements of such semigroups in combinatorial terms (chips, colored graphs,…

Representation Theory · Mathematics 2018-01-23 Yury A. Neretin

Any convex polytope whose combinatorial automorphism group has two orbits on the flags is isomorphic to one whose group of Euclidean symmetries has two orbits on the flags (equivalently, to one whose automorphism group and symmetry group…

Metric Geometry · Mathematics 2016-03-09 Nicholas Matteo

We survey results on the problem of covering the space ${\mathbb R}^n$, or a convex body in it, by translates of a convex body. Our main goal is to present a diverse set of methods. A theorem of Rogers is a central result, according to…

Metric Geometry · Mathematics 2016-03-16 Márton Naszódi

Abstract polytopes generalize the classical notion of convex polytopes to more general combinatorial structures. The most studied ones are regular and chiral polytopes, as it is well-known, they can be constructed as coset geometries from…

Combinatorics · Mathematics 2023-04-06 Isabel Hubard , Elías Mochán

We describe families of plane-filling curves on any edge-to-edge tiling of the plane with regular polygons and finitely many classes of edges. It is shown how to partition the minimal number of edge classes from the group G of symmetries of…

Combinatorics · Mathematics 2023-12-04 Jörg Arndt , Julia Handl

We investigate small covers and quasitoric over the duals of neighborly simplicial polytopes with small number of vertices in dimensions $4$, $5$, $6$ and $7$. In the most of the considered cases we obtain the complete classification of…

Algebraic Topology · Mathematics 2017-04-21 Djordje Baralic , Lazar Milenkovic

Using a recent description of the geometric stability manifold, we show the geometric stability manifold associated to any smooth projective complex surface is contractible. We then use this result to demonstrate infinitely many new…

Algebraic Geometry · Mathematics 2024-05-24 Nick Rekuski

We study a combinatorial notion where given a set of lattice points one takes the set of all sums of subsets of a fixed size, and we ask if the given set comes from a convex lattice polytope whether the resulting set also comes from a…

Combinatorics · Mathematics 2021-08-03 Alexander Lemmens

For convex partitions of a convex body $B$ we prove that we can put a homothetic copy of $B$ into each set of the partition so that the sum of homothety coefficients is $\ge 1$. In the plane the partition may be arbitrary, while in higher…

Combinatorics · Mathematics 2012-12-27 Arseniy Akopyan , Roman Karasev

We obtain improved upper bounds and new lower bounds on the chromatic number as a linear function of the clique number, for the intersection graphs (and their complements) of finite families of translates and homothets of a convex body in…

Discrete Mathematics · Computer Science 2010-08-10 Adrian Dumitrescu , Minghui Jiang

Hexagonal polyominoes are polyominoes on the honeycomb lattice. We enumerate the symmetry classes of convex hexagonal polyominoes. Here convexity is to be understood as convexity along the three main column directions. We deduce the…

Combinatorics · Mathematics 2007-05-23 Dominique Gouyou-Beauchamps , Pierre Leroux

In the MINIMUM CONVEX COVER (MCC) problem, we are given a simple polygon $\mathcal P$ and an integer $k$, and the question is if there exist $k$ convex polygons whose union is $\mathcal P$. It is known that MCC is $\mathsf{NP}$-hard…

Computational Geometry · Computer Science 2021-06-07 Mikkel Abrahamsen

We define and study a new family of polytopes which are formed as convex hulls of partial alternating sign matrices. We determine the inequality descriptions, number of facets, and face lattices of these polytopes. We also study partial…

Combinatorics · Mathematics 2022-03-09 Dylan Heuer , Jessica Striker

We investigate how to make the surface of a convex polyhedron (a polytope) by folding up a polygon and gluing its perimeter shut, and the reverse process of cutting open a polytope and unfolding it to a polygon. We explore basic enumeration…

Computational Geometry · Computer Science 2007-05-23 Erik D. Demaine , Martin L. Demaine , Anna Lubiw , Joseph O'Rourke

In this study, the properties of convex pentagons that can form rotationally symmetric edge-to-edge tilings are discussed. Because the rotationally symmetric tilings are formed by concave octagons that are generated by two convex pentagons…

Metric Geometry · Mathematics 2022-05-04 Teruhisa Sugimoto

A convex polyhedron, that is, a compact convex subset of $\mathbb{R}^3$ which is the intersection of finitely many closed half-spaces, can be rectified by taking the convex hull of the midpoints of the edges of the polyhedron. We derive…

Metric Geometry · Mathematics 2016-04-05 Samuel Reid
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