Global optimization methods applied to machine learning. Using optimization to build optimal and sparse decision trees; Use of optimization methods to build explainable artificial intelligence tools. I am the coordinator of the global optimization laboratory https://webgol.dinfo.unifi.it/, a scientific research lab devoted to optimization and machine learning. Our group consists of three professors and around 10 PhD or PostDoc students, plus a large group of graduate students. We are active in the field of optimization as well as in machinelearning (also thanks to external collaborations, e.g., on object recognition in videos). We are just entering the world of interpretable machine learning. We had a graduate student working on optimal decision trees and we currently have two PhD students working on extending that research. We have also good connection with research hospitals, who might benefit from an optimizaed explainable decision support.