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We present new computations of approximately length-minimizing polygons with fixed thickness. These curves model the centerlines of "tight" knotted tubes with minimal length and fixed circular cross-section. Our curves approximately…

Differential Geometry · Mathematics 2010-02-10 Ted Ashton , Jason Cantarella , Michael Piatek , Eric Rawdon

The lattice dimension of a graph G is the minimal dimension of a cubic lattice in which G can be isometrically embedded. We prove that the lattice dimension of a tree with n leaves is $\lceil n/2 \rceil$.

Combinatorics · Mathematics 2007-05-23 Sergei Ovchinnikov

A non-crossing spanning tree of a set of points in the plane is a spanning tree whose edges pairwise do not cross. Avis and Fukuda in 1996 proved that there always exists a flip sequence of length at most $2n-4$ between any pair of…

Computational Geometry · Computer Science 2023-11-01 Nicolas Bousquet , Lucas De Meyer , Théo Pierron , Alexandra Wesolek

We revisit the \textsc{$k$-Secluded Tree} problem. Given a vertex-weighted undirected graph $G$, its objective is to find a maximum-weight induced subtree $T$ whose open neighborhood has size at most $k$. We present a fixed-parameter…

Data Structures and Algorithms · Computer Science 2022-06-27 Huib Donkers , Bart M. P. Jansen , Jari J. H. de Kroon

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

It is known that for every $\alpha \geq 1$ there is a planar triangulation in which every ball of radius $r$ has size $\Theta(r^\alpha)$. We prove that for $\alpha <2$ every such triangulation is quasi-isometric to a tree. The result…

Metric Geometry · Mathematics 2022-05-27 Itai Benjamini , Agelos Georgakopoulos

We show an algorithm that, given an $n$-vertex graph $G$ and a parameter $k$, in time $2^{O(k \log k)} n^{O(1)}$ finds a tree decomposition of $G$ with the following properties: * every adhesion of the tree decomposition is of size at most…

Data Structures and Algorithms · Computer Science 2020-09-29 Marek Cygan , Paweł Komosa , Daniel Lokshtanov , Michał Pilipczuk , Marcin Pilipczuk , Saket Saurabh , Magnus Wahlström

We prove that one can perfectly pack degenerate graphs into complete or dense $n$-vertex quasirandom graphs, provided that all the degenerate graphs have maximum degree $o(\frac{n}{\log n})$, and in addition $\Omega(n)$ of them have at most…

Combinatorics · Mathematics 2019-06-28 Peter Allen , Julia Böttcher , Dennis Clemens , Anusch Taraz

In this paper we consider the problem of connected edge searching of weighted trees. It is shown that there exists a polynomial-time algorithm for finding optimal connected search strategy for bounded degree trees with arbitrary weights on…

Data Structures and Algorithms · Computer Science 2021-03-05 Dariusz Dereniowski

We define simple variants of zip trees, called zip-zip trees, which provide several advantages over zip trees, including overcoming a bias that favors smaller keys over larger ones. We analyze zip-zip trees theoretically and empirically,…

Data Structures and Algorithms · Computer Science 2025-02-11 Ofek Gila , Michael T. Goodrich , Robert E. Tarjan

We consider packing tree degree sequences in this paper. We set up a conjecture that any arbitrary number of tree degree sequences without common leaves have edge disjoint tree realizations. This conjecture is known to be true for $2$ and…

Combinatorics · Mathematics 2017-04-12 Aravind Gollakota , William Hardt , Istvan Miklos

Diestel and M\"uller showed that the connected tree-width of a graph $G$, i.e., the minimum width of any tree-decomposition with connected parts, can be bounded in terms of the tree-width of $G$ and the largest length of a geodesic cycle in…

Combinatorics · Mathematics 2017-02-15 Matthias Hamann , Daniel Weißauer

The classic Maxwell formula calculates the length of a planar locally minimal binary tree in terms of coordinates of its boundary vertices and directions of incoming edges. However, if an extreme tree with a given topology and a boundary…

Metric Geometry · Mathematics 2011-01-12 A. O. Ivanov , A. A. Tuzhilin

In this article, we construct explicit examples of pairs of non-isomorphic trees with the same restricted $U$-polynomial for every $k$; by this we mean that the polynomials agree on terms with degree at most $k+1$. The main tool for this…

Combinatorics · Mathematics 2020-02-20 José Aliste-Prieto , Anna de Mier , José Zamora

Let $G$ be a graph and let $f$ be a positive integer-valued function on $V(G)$. In this paper, we show that if for all $S\subseteq V(G)$, $\omega(G\setminus S)<\sum_{v\in S}(f(v)-2)+2+\omega(G[S])$, then $G$ has a spanning tree $T$…

Combinatorics · Mathematics 2022-05-10 Morteza Hasanvand

A labeled oriented graph (LOG) is an oriented graph with a labeling function from the edge set into the vertex set. The complexity of a LOG is the minimal cardinality of an initial set $S$ of vertices such that every vertex can be reached…

Combinatorics · Mathematics 2014-12-24 Moritz Christmann , Timo de Wolff

The classical matrix tree theorem relates the number of spanning trees of a connected graph with the product of the nonzero eigenvalues of its Laplacian matrix. The class of regular matroids generalizes that of graphical matroids, and a…

Combinatorics · Mathematics 2014-05-12 Aaron Dall , Julian Pfeifle

In this paper, we study how to draw trees so that they are planar, straight-line and respect a given order of edges around each node. We focus on minimizing the height, and show that we can always achieve a height of at most 2pw(T)+1, where…

Computational Geometry · Computer Science 2016-06-08 Johannes Batzill , Therese Biedl

Let $T$ be a tree on $t$ vertices. We prove that for every positive integer $k$ and every graph $G$, either $G$ contains $k$ pairwise vertex-disjoint subgraphs each having a $T$ minor, or there exists a set $X$ of at most $t(k-1)$ vertices…

Combinatorics · Mathematics 2025-02-25 Vida Dujmović , Gwenaël Joret , Piotr Micek , Pat Morin

We study the problem of guarding the boundary of a simple polygon with a minimum number of guards such that each guard covers a contiguous portion of the boundary. First, we present a simple greedy algorithm for this problem that returns a…

Computational Geometry · Computer Science 2025-05-09 Ahmad Biniaz , Anil Maheshwari , Joseph S. B. Mitchell , Saeed Odak , Valentin Polishchuk , Thomas Shermer