Borel subsystems and ergodic universality for compact ${\mathbb{Z}}^d$-systems via specification and beyond

Nishant Chandgotia, Tom Meyerovitch

A Borel system $(X,S)$ is `almost Borel universal' if any free Borel dynamical system $(Y,T)$ of strictly lower entropy is isomorphic to a Borel subsystem of $(X,S)$, after removin…