An extremal graph problem on a grid and an isoperimetric problem for polyominoes
The electronic journal of combinatorics, Tome 31 (2024) no. 2
Let $G$ denote the infinite grid graph with vertex set $\{(a,b)\ : \, a,b \in \mathbb{Z}\}$ and edge set $\big \{ \{u,v\} : |u-v|=1 \;\text{or}\; |u-v| = \sqrt{2} \big \}.$ A question in landscape ecology, restated in graph theoretic terms, asks the following. What is the maximum number of edges in an induced subgraph of $G$ of order $n$? It was conjectured by Taliceo and Fleron that the maximum is $4n - \big \lceil \sqrt{28n-12} \, \big \rceil$. We prove the conjecture by formulating and solving a discrete version of the classical isoperimeteric problem.
DOI :
10.37236/12133
Classification :
05B50, 05C35, 05C10, 05C30, 52B60
Mots-clés : dual polyomino, isoperimetric functions
Mots-clés : dual polyomino, isoperimetric functions
Affiliations des auteurs :
Andrew Vince  1
@article{10_37236_12133,
author = {Andrew Vince},
title = {An extremal graph problem on a grid and an isoperimetric problem for polyominoes},
journal = {The electronic journal of combinatorics},
year = {2024},
volume = {31},
number = {2},
doi = {10.37236/12133},
zbl = {1536.05131},
url = {http://geodesic.mathdoc.fr/articles/10.37236/12133/}
}
Andrew Vince. An extremal graph problem on a grid and an isoperimetric problem for polyominoes. The electronic journal of combinatorics, Tome 31 (2024) no. 2. doi: 10.37236/12133
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