An improved polynomial $χ$-bound for $\{P_5,C_5\}$-free graphs

Abstract

Nguyen~\cite{Nguyen2025} recently proved that every $\{P_5,C_5\}$-free graph $G$ satisfies $χ(G)\leq ω(G)^{40}$. Building on his framework, we introduce two refinements, namely a sharper cutset decomposition using the $C_5$-free condition and an improved density-increment argument. These yield a polynomial $χ$-binding function with exponent $24$, improving the previous bound of $40$.