Invariant hypersurfaces of endomorphisms of the projective 3-space
  We consider surjective endomorphisms f of degree > 1 on the projective n-space with n = 3, and f^{-1}-stable hypersurfaces V. We show that V is a hyperplane (i.e., deg(V) = 1) but with four possible exceptions; it is conjectured that deg(V) = 1 for any n > 1. 
De-Qi Zhang
math.AG math.DS