Xavier Fernández-Real Girona is SNF Ambizione Fellow at EPFL. He received his PhD in Mathematics from ETH Zürich in 2020, for which he received the Dimitris N. Chorafas Prize as well as the Vicent Caselles Prize. He is the winner of the Rubio de Francia Prize from the Royal Spanish Mathematical Society and the Antonio Valle Young Researcher Award from the Spanish Society of Applied Mathematics. He is author of the book 'Regularity Theory for Elliptic PDE', jointly written with X. Ros-Oton. Xavier Ros Oton is ICREA Research Professor at Universitat de Barcelona since 2020. Previously, he has been Assistant Professor at Universität Zürich, as well as R. H. Bing Instructor at the University of Texas at Austin. He has received several awards for young mathematicians in Spain, including the 'Premio Nacional de Investigación' for researchers under 40 in Mathematics and Computer Science. He also received the Scientific Research Award from the Fundación Princesa de Girona, as well as the Stampacchia Gold Medal. In 2022, he was elected member of the Spanish Royal Academy of Sciences.