Toward Grünbaum's Conjecture

Fuente: arXiv
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Main Authors: Ortlieb, Christian, Schmidt, Jens M.
Format: Preprint
Published: 2024
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author Ortlieb, Christian
Schmidt, Jens M.
author_facet Ortlieb, Christian
Schmidt, Jens M.
contents Given a spanning tree $T$ of a planar graph $G$, the co-tree of $T$ is the spanning tree of the dual graph $G^*$ with edge set $(E(G)-E(T))^*$. Grünbaum conjectured in 1970 that every planar 3-connected graph $G$ contains a spanning tree $T$ such that both $T$ and its co-tree have maximum degree at most 3. While Grünbaum's conjecture remains open, Biedl proved that there is a spanning tree $T$ such that $T$ and its co-tree have maximum degree at most 5. By using new structural insights into Schnyder woods, we prove that there is a spanning tree $T$ such that $T$ and its co-tree have maximum degree at most 4.
format Preprint
id arxiv_https___arxiv_org_abs_2402_05681
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Toward Grünbaum's Conjecture
Ortlieb, Christian
Schmidt, Jens M.
Discrete Mathematics
Combinatorics
Given a spanning tree $T$ of a planar graph $G$, the co-tree of $T$ is the spanning tree of the dual graph $G^*$ with edge set $(E(G)-E(T))^*$. Grünbaum conjectured in 1970 that every planar 3-connected graph $G$ contains a spanning tree $T$ such that both $T$ and its co-tree have maximum degree at most 3. While Grünbaum's conjecture remains open, Biedl proved that there is a spanning tree $T$ such that $T$ and its co-tree have maximum degree at most 5. By using new structural insights into Schnyder woods, we prove that there is a spanning tree $T$ such that $T$ and its co-tree have maximum degree at most 4.
title Toward Grünbaum's Conjecture
topic Discrete Mathematics
Combinatorics
url https://arxiv.org/abs/2402.05681