Robert M. Polzin, Freie Universität Berlin

**"What is... a coherent set?"**

Dynamical systems often exhibit the emergence of long-lived coherent sets. These sets are regions in state space that keep their geometric integrity to a high extent. In this talk, a well-known method for extracting coherent sets from possibly sparse Lagrangian trajectory data is discussed. This method can be seen as an extension of diffusion maps to trajectory space. It reveals the intrinsic low-dimensional organization of the data with respect to transport.