The energy-critical nonlinear Schr\"odinger equation on a product of   spheres
  Let $(M,g)$ be a compact smooth $3$-dimensional Riemannian manifold without boundary. It is proved that the energy-critical nonlinear Schr\"odinger equation is globally well-posed for small initial data in $H^1(M)$, provided that a certain tri-linear estimate for free solutions holds true. This estimate is known to hold true on the sphere and tori in $3d$ and verified here in the case $\mathbb{S}\times\mathbb{S}^2$. The necessity of a weak form of this tri-linear estimate is also discussed. 
Sebastian Herr, Nils Strunk
math.AP