The effect of domain shape on the number of positive and nodal solutions for semilinear elliptic equations

In this paper, we study the effect of domain shape on the number of positive and nodal (sign-changing) solutions for a class of semilinear elliptic equations. We prove a semilinear elliptic equation in a domain ΩΩ that contains mm disjoint large enough balls has m2m2 2-nodal solutions and mm positive solutions.