Kohn–Rossi cohomology and nonexistence of CR morphisms between compact strongly pseudoconvex CR manifolds

Abstract

One of the fundamental questions in CR geometry is: Given two strongly pseudoconvex CR manifolds X1 and X2 of dimension 2n−1, is there a non-constant CR morphism between them? In this paper, we use Kohn-Rossi cohomology to show the non-existence of non-constant CR morphism between such two CR manifolds. Specifically, if dimH KR(X1) < dimH p,q KR(X2) for any (p, q) with 1 ≤ q ≤ n− 2, then there is no non-constant CR morphism from X1 to X2.