Existence And Multiplicity Of Solutions To Biharmonic Problems With Hardy-Sobolev Critical Exponents

This paper is concerned with the following biharmonic problems:#12 where ? be a bounded C3,1 domain containing the origin in RN,and?? is smooth boundary.0<?<4<N,?>0 is a parameter,and 2**(?)=2(N-?/N-4 is the Hardy-Soboiev critical exponent.We prove some new existence and multiplicity results for the above problem by a critical point theorem based on Z2-cohomological index and another critical point theorem based on pseudo index.