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We prove that for any finite tree $T$ with $n$ vertices and maximal degree $3$, there is a topological embedding of $T$ into the integer grid $Z^2$ which maps vertices to vertices and whose image meets at most $\frac{7}{3}n$ vertices. This…

Metric Geometry · Mathematics 2024-01-29 Samuel Kelly

A long-standing conjecture by Albertson and Berman states that every planar graph of order $n$ has an induced forest with at least $\lceil \frac{n}{2} \rceil$ vertices. As a variant of this conjecture, Chappell conjectured that every planar…

Discrete Mathematics · Computer Science 2025-05-30 Naoki Matsumoto , Takamasa Yashima

We investigate two notions of saturation for partial planar embeddings of maximal planar graphs. Let $G = (V, E) $ be a vertex-labeled maximal planar graph on $ n $ vertices, which by definition has $3n - 6$ edges. We say that a labeled…

Combinatorics · Mathematics 2024-12-10 Alexander Clifton , Dániel G. Simon

We prove that every 3-connected planar graph on $n$ vertices contains an induced path on $\Omega(\log n)$ vertices, which is best possible and improves the best known lower bound by a multiplicative factor of $\log \log n$. We deduce that…

Combinatorics · Mathematics 2016-12-20 Louis Esperet , Laetitia Lemoine , Frédéric Maffray

In this paper, we study the following question. Let $\mathcal G$ be a family of planar graphs and let $k\geq 3$ be an integer. What is the largest value $f_k(n)$ such that every $n$-vertex graph in $\mathcal G$ has an induced subgraph with…

Combinatorics · Mathematics 2025-11-26 Marco D'Elia , Fabrizio Frati

In response to a well-known open question ``Does every complete geometric graph on $2n\/$ vertices have a partition of its edge set into $n\/$ plane spanning trees?" we provide an affirmative answer when the complete geometry graph is in…

Combinatorics · Mathematics 2019-06-14 Hazim Michman Trao , Gek L. Chia , Niran Abbas Ali , Adem Kilicman

Every finite graph admits a \emph{simple (topological) drawing}, that is, a drawing where every pair of edges intersects in at most one point. However, in combination with other restrictions simple drawings do not universally exist. For…

Computational Geometry · Computer Science 2020-08-26 Michael Hoffmann , Chih-Hung Liu , Meghana M. Reddy , Csaba D. Tóth

Traditional representations of graphs and their duals suggest the requirement that the dual vertices be placed inside their corresponding primal faces, and the edges of the dual graph cross only their corresponding primal edges. We consider…

Computational Geometry · Computer Science 2007-05-23 C. Erten , S. G. Kobourov

We prove that if an $n$-vertex graph $G$ can be drawn in the plane such that each pair of crossing edges is independent and there is a crossing-free edge that connects their endpoints, then $G$ has $O(n)$ edges. Graphs that admit such…

Combinatorics · Mathematics 2016-08-31 Eyal Ackerman , Balázs Keszegh , Mate Vizer

The $n$-$book ~embedding$ of a graph $G$ is an embedding of the graph $G$ in an $n$-book with the vertices of $G$ on the spine and each edge to the pages without crossing each other. If the degree of vertices of $G$ at most one in each…

Combinatorics · Mathematics 2022-08-15 Zeling Shao , Yanqing Liu , Zhiguo Li

We give a simple proof that every $n$-vertex graph $d$-regular graph that does not contain a fixed bipartite graph as a subgraph has an induced matching of size $\Omega((n/d)(\log d))$.

Combinatorics · Mathematics 2020-09-22 Ben Lund , Daniel Reichman

We call a (not necessarily planar) embedding of a graph $G$ in the plane \emph{sequential} if its vertices lie in $\mathbb Z^2$ and the line segments between adjacent vertices contain no interior integer points. In this note, we prove (i) a…

Combinatorics · Mathematics 2018-12-10 Jackson Autry , Christopher O'Neill

Two graphs $G_1=(V,E_1)$ and $G_2=(V,E_2)$ admit a geometric simultaneous embedding if there exists a set of points P and a bijection M: P -> V that induce planar straight-line embeddings both for $G_1$ and for $G_2$. While it is known that…

Computational Geometry · Computer Science 2010-01-05 Patrizio Angelini , Markus Geyer , Michael Kaufmann , Daniel Neuwirth

It follows from the work of Tait and the Four-Color-Theorem that a planar cubic graph is 3-edge-colorable if and only if it contains no bridge. We consider the question of which planar graphs are subgraphs of planar cubic bridgeless graphs,…

Data Structures and Algorithms · Computer Science 2022-07-18 Miriam Goetze , Paul Jungeblut , Torsten Ueckerdt

In a planar L-drawing of a directed graph (digraph) each edge e is represented as a polyline composed of a vertical segment starting at the tail of e and a horizontal segment ending at the head of e. Distinct edges may overlap, but not…

Computational Geometry · Computer Science 2020-08-19 Patrizio Angelini , Steven Chaplick , Sabine Cornelsen , Giordano Da Lozzo

A set of colored graphs are compatible, if for every color $i$, the number of vertices of color $i$ is the same in every graph. A simultaneous embedding of $k$ compatibly colored graphs, each with $n$ vertices, consists of $k$ planar…

Computational Geometry · Computer Science 2021-01-19 Debajyoti Mondal

An embedding of a graph in a book, called book embedding, consists of a linear ordering of its vertices along the spine of the book and an assignment of its edges to the pages of the book, so that no two edges on the same page cross. The…

For every $n\in \mathbb{N}$, we present a set $S_n$ of $O(n^{3/2}\log n)$ points in the plane such that every planar 3-tree with $n$ vertices has a straight-line embedding in the plane in which the vertices are mapped to a subset of $S_n$.…

Computational Geometry · Computer Science 2013-10-02 Radoslav Fulek , Csaba D. Tóth

In an $\mathsf{L}$-embedding of a graph, each vertex is represented by an $\mathsf{L}$-segment, and two segments intersect each other if and only if the corresponding vertices are adjacent in the graph. If the corner of each…

Computational Geometry · Computer Science 2017-03-07 Abu Reyan Ahmed , Felice De Luca , Sabin Devkota , Alon Efrat , Md Iqbal Hossain , Stephen Kobourov , Jixian Li , Sammi Abida Salma , Eric Welch

We show that every graph has an induced pseudoforest of at least $n-m/4.5$ vertices, an induced partial 2-tree of at least $n-m/5$ vertices, and an induced planar subgraph of at least $n-m/5.2174$ vertices. These results are constructive,…

Computational Geometry · Computer Science 2015-07-16 Glencora Borradaile , David Eppstein , Pingan Zhu