constraint variation造句

in this paper, we consider a class of nonlinear elliptic equations . with the method of constraint variation, we obtain the existence of the solutions for the equations
摘要本文考虑一类非线性椭圆方程。运用强制变分方法，我们给出了在多种情况下方程解的存在性。
It's difficult to find constraint variation in a sentence. 用constraint variation造句挺难的