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A \emph{book-embedding} of a graph $G$ is an embedding of vertices of $G$ along the spine of a book, and edges of $G$ on the pages so that no two edges on the same page intersect. the minimum number of pages in which a graph can be embedded…

Combinatorics · Mathematics 2018-01-23 Xiaxia Guan , Weihua Yang

We prove that there is $c>0$ such that for all sufficiently large $n$, if $T_1,\dots,T_n$ are any trees such that $T_i$ has $i$ vertices and maximum degree at most $cn/\log n$, then $\{T_1,\dots,T_n\}$ packs into $K_n$. Our main result…

Combinatorics · Mathematics 2022-06-22 Peter Allen , Julia Böttcher , Dennis Clemens , Jan Hladký , Diana Piguet , Anusch Taraz

An embedding is a mapping from a set of nodes of a network into a real vector space. Embeddings can have various aims like capturing the underlying graph topology and structure, node-to-node relationship, or other relevant information about…

Machine Learning · Computer Science 2023-06-21 Ashkan Dehghan , Kinga Siuta , Agata Skorupka , Andrei Betlen , David Miller , Bogumil Kaminski , Pawel Pralat

We study the problem of learning a latent tree graphical model where samples are available only from a subset of variables. We propose two consistent and computationally efficient algorithms for learning minimal latent trees, that is, trees…

Machine Learning · Statistics 2010-09-15 Myung Jin Choi , Vincent Y. F. Tan , Animashree Anandkumar , Alan S. Willsky

The goal of ordinal embedding is to represent items as points in a low-dimensional Euclidean space given a set of constraints in the form of distance comparisons like "item $i$ is closer to item $j$ than item $k$". Ordinal constraints like…

Machine Learning · Statistics 2016-06-24 Lalit Jain , Kevin Jamieson , Robert Nowak

The metric dimension of a graph is the minimum size of a set of vertices such that each vertex is uniquely determined by the distances to the vertices of that set. Our aim is to upper-bound the order $n$ of a graph in terms of its diameter…

Sorting is a foundational problem in computer science that is typically employed on sequences or total orders. More recently, a more general form of sorting on partially ordered sets (or posets), where some pairs of elements are…

Data Structures and Algorithms · Computer Science 2022-06-03 Jishnu Roychoudhury , Jatin Yadav

Let $G$ be a connected graph and $W$ be a set of vertices of $G$. The representation multiset of a vertex $v$ with respect to $W$, $r_m (v|W)$, is defined as a multiset of distances between $v$ and the vertices in $W$. If $r_m (u |W) \neq…

We derive a sufficient condition for a sparse graph G on n vertices to contain a copy of a tree T of maximum degree at most d on (1-\epsilon)n vertices, in terms of the expansion properties of G. As a result we show that for fixed d\geq 2…

Combinatorics · Mathematics 2007-06-29 Noga Alon , Michael Krivelevich , Benny Sudakov

We define a special case of tree decompositions for planar graphs that respect a given embedding of the graph. We study the analogous width of the resulting decomposition we call the embedded-width of a plane graph. We show both upper…

Discrete Mathematics · Computer Science 2017-03-23 Glencora Borradaile , Jeff Erickson , Hung Le , Robbie Weber

Given a rooted tree $T$ with vertices $u_1,u_2,\ldots,u_n$, the level matrix $L(T)$ of $T$ is the $n \times n$ matrix for which the $(i,j)$-th entry is the absolute difference of the distances from the root to $v_i$ and $v_j$. This matrix…

Combinatorics · Mathematics 2023-09-21 Audace A. V. Dossou-Olory

Motivated by the study of pattern avoidance in the context of permutations and ordered partitions, we consider the enumeration of weak-ordering chains obtained as leaves of certain restricted rooted trees. A tree of order $n$ is generated…

Combinatorics · Mathematics 2023-06-22 Daniel Birmajer , Juan B. Gil , David S. Kenepp , Michael D. Weiner

In this paper, we introduce a bisected vertex leveling of a plane graph. Using this planar embedding, we present elementary proofs of the well-known upper bounds in terms of the minimal crossing number on braid index $b(L)$ and arc index…

Geometric Topology · Mathematics 2018-06-27 Sungjong No , Seungsang Oh , Hyungkee Yoo

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

Let $G$ be a simple graph on $n$ vertices. We consider the problem LIS of deciding whether there exists an induced subtree with exactly $i \leq n$ vertices and $\ell$ leaves in $G$. We study the associated optimization problem, that…

Data Structures and Algorithms · Computer Science 2018-07-10 Alexandre Blondin Massé , Julien de Carufel , Alain Goupil , Mélodie Lapointe , Émile Nadeau , Élise Vandomme

In a book embedding, the vertices of a graph are placed on the spine of a book and the edges are assigned to pages, so that edges on the same page do not cross. In this paper, we prove that every $1$-planar graph (that is, a graph that can…

Data Structures and Algorithms · Computer Science 2015-03-31 Michael A. Bekos , Till Bruckdorfer , Michael Kaufmann , Chrysanthi N. Raftopoulou

Suppose that there is a family of $n$ random points $X_v$ for $v \in V$, independently and uniformly distributed in the square $\left[-\sqrt{n}/2,\sqrt{n}/2\right]^2$ of area $n$. We do not see these points, but learn about them in one of…

Probability · Mathematics 2019-11-26 Josep Diaz , Colin McDiarmid , Dieter Mitsche

Let $G = (V,E)$ denote a simple graph with the vertex set $V$ and the edge set $E$. The profile of a vertex set $V'\subseteq V$ denotes the multiset of pairwise distances between the vertices of $V'$. Two disjoint subsets of $V$ are…

Combinatorics · Mathematics 2013-11-08 Radoslav Fulek , Slobodan Mitrović

Let $\mathcal{T}$ be a rooted and weighted tree, where the weight of any node is equal to the sum of the weights of its children. The popular Treemap algorithm visualizes such a tree as a hierarchical partition of a square into rectangles,…

Computational Geometry · Computer Science 2013-12-17 Mark de Berg , Krzysztof Onak , Anastasios Sidiropoulos

Let $G$ be an undirected graph. We say that $G$ contains a ladder of length $k$ if the $2 \times (k+1)$ grid graph is an induced subgraph of $G$ that is only connected to the rest of $G$ via its four cornerpoints. We prove that if all the…

Combinatorics · Mathematics 2024-01-31 Steven Chaplick , Steven Kelk , Ruben Meuwese , Matus Mihalak , Georgios Stamoulis