On the Anti-Ramsey Number of Spanning Linear Forests with Paths of Lengths 2 and 3 (2509.25949v1)

Abstract: An edge-coloring of a graph $G$ assigns a color to each edge in the edge set $E(G)$. A graph $G$ is considered to be rainbow under an edge-coloring if all of its edges have different colors. For a positive integer $n$, the anti-Ramsey number of a graph $G$, denoted as $AR(n, G)$, represents the maximum number of colors that can be used in an edge-coloring of the complete graph $K_n$ without containing a rainbow copy of $G$. This concept was introduced by Erd\H{o}s et al. in 1975. The anti-Ramsey number for the linear forest $kP_3 \cup tP_2$ has been extensively studied for two positive integers $k$ and $t$. Formulations exist for specific values of $t$ and $k$, particularly when $k \geq 2$, $t \geq \frac{k^2 - k + 4}{2}$, and $n \geq 3k + 2t + 1$. In this work, we present the anti-Ramsey number of the linear forest $kP_3 \cup tP_2$ for the case where $k \geq 1$, $t \geq 2$, and $n = 3k + 2t$. Notably, our proof for this case does not require any specific relationship between $k$ and $t$.