Solvable Nonlinear Evolution PDEs in Multidimensional Space
  A class of solvable (systems of) nonlinear evolution PDEs in multidimensional space is discussed. We focus on a rotation-invariant system of PDEs of Schr\"odinger type and on a relativistically-invariant system of PDEs of Klein-Gordon type. Isochronous variants of these evolution PDEs are also considered. 
Francesco Calogero and Matteo Sommacal