
arXiv: 1709.00970
Motivated by anti-Ramsey numbers introduced by Erd��s, Simonovits and S��s in 1975, we study the anti-Ramsey problem when host graphs are plane triangulations. Given a positive integer $n$ and a planar graph $H$, let $\mathcal{T}_n(H)$ be the family of all plane triangulations $T$ on $n$ vertices such that $T$ contains a subgraph isomorphic to $H$. The planar anti-Ramsey number of $H$, denoted $ar_{_\mathcal{P}}(n, H)$, is the maximum number of colors in an edge-coloring of a plane triangulation $T\in \mathcal{T}_n(H)$ such that $T$ contains no rainbow copy of $H$. Analogous to anti-Ramsey numbers and Tur��n numbers, planar anti-Ramsey numbers are closely related to planar Tur��n numbers, where the planar Tur��n number of $H$ is the maximum number of edges of a planar graph on $n$ vertices without containing $H$ as a subgraph. The study of $ar_{_\mathcal{P}}(n, H)$ (under the name of rainbow numbers) was initiated by Hor����k, Jendrol$'$, Schiermeyer and Sot��k [J Graph Theory 78 (2015) 248--257]. In this paper we study planar anti-Ramsey numbers for paths and cycles. We first establish lower bounds for $ar_{_\mathcal{P}}(n, P_k)$ when $n\ge k\ge8$. We then improve the existing lower bound for $ar_{_\mathcal{P}}(n, C_k)$ when $k\geq 5$ and $n\geq k^2-k$. Finally, using the main ideas in the above-mentioned paper, we obtain upper bounds for $ar_{_\mathcal{P}}(n, C_6)$ when $n\ge8$ and $ar_{_\mathcal{P}}(n, C_7)$ when $n\geq 13$, respectively.
16 pages, 3 figures, an error in the definition of planar anti-Ramsey numbers is fixed
Coloring of graphs and hypergraphs, Ramsey theory, FOS: Mathematics, Generalized Ramsey theory, anti-Ramsey number, Mathematics - Combinatorics, plane triangulation, Combinatorics (math.CO), rainbow subgraph
Coloring of graphs and hypergraphs, Ramsey theory, FOS: Mathematics, Generalized Ramsey theory, anti-Ramsey number, Mathematics - Combinatorics, plane triangulation, Combinatorics (math.CO), rainbow subgraph
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