# Online Talk: Sophie Spirkl and James Davies

Tuesday, Feb 8, 3pm ET (8pm GMT, 9am Wed NZDT)
Sophie Spirkl and James Davies, University of Waterloo
Two counterexamples related to chi-boundedness

##### Sophie Spirkl: I will present a counterexample to the following well-known conjecture: for every $k$, $r$, every graph $G$ with clique number at most $k$ and sufficiently large chromatic number contains a triangle-free induced subgraph with chromatic number at least $r$. Joint work with Alvaro Carbonero, Patrick Hompe, and Benjamin Moore.James Davies: We construct hereditary classes of graphs that are $\chi$-bounded but not polynomially $\chi$-bounded.Joint work with Marcin Briański and Bartosz Walczak.

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