Constant-factor upper bound for the indicated chromatic number

Determine whether there exists a universal constant C such that every graph G satisfies \(\chi_i(G) \le C\chi(G)\), where \(\chi_i(G)\) is the indicated chromatic number and \(\chi(G)\) is the chromatic number.

Background

The paper studies the indicated chromatic number χi(G)\chi_i(G), arising from the indicated colouring game, and compares it with the ordinary chromatic number χ(G)\chi(G). Previously known constructions gave graphs with arbitrarily large chromatic number for which the ratio χi(G)/χ(G)\chi_i(G)/\chi(G) is at least approximately $3/2$. The authors improve the known lower-ratio examples but do not determine whether the indicated chromatic number is universally bounded by a constant multiple of the chromatic number.

References

It remains an open question whether $\chi_i(G) \le C \chi(G)$ for some constant $C$.

Indicated list colouring game on graphs  (2502.16073 - Gu et al., 22 Feb 2025) in Introduction