the existence and multiplicity results are obtained for a class of fourth-order nonlinear elliptic equations by the least action principle and the minimax methods, respectively.
通过极小化作用原理和极小极大方法得到了一类四阶非线性椭圆方程解的存在性和多重性。
existence and multiplicity results for elliptic equation and quasilinear elliptic systems with variational structure have been broadly investigated.