**Tuesday, Feb 15,** **4****pm ET** (9pm GMT, 10am Wed NZDT)**Chun-Hung Liu**, Texas A&M University**Homomorphism counts in robustly sparse graphs**

**YouTube:**https://youtu.be/iIFri6hTQ3E

**Tuesday, Feb 15,** **4****pm ET** (9pm GMT, 10am Wed NZDT)**Chun-Hung Liu**, Texas A&M University**Homomorphism counts in robustly sparse graphs**

of homomorphisms from $H$ to $G$ and the number of subgraphs isomorphic to $H$

contained in $G$ have been extensively studied when the host graphs are

allowed to be dense. This talk addresses the case when the host graphs

are robustly sparse. We determine, up to a constant multiplicative

error, the maximum number of subgraphs isomorphic to $H$ contained in an

$n$-vertex graph in any fixed hereditary graph class with bounded

expansion. This result solves a number of open questions and can be

generalized to counting the number of homomorphisms.