文摘
We propose a numerical method with the nonconforming \(\mathcal {P}_1\) FEM to verify the existence of solutions to an elliptic boundary value problem. Formulating the boundary value problem as a fixed-point problem on the sum space of the nonconforming \(\mathcal {P}_1\) finite element space with the Sobolev space of 1st order with zero Dirichlet condition, we construct the numerical verification method based on the Schauder fixed-point theorem. We show a constructive inequality for a boundary integral that appears due to the discontinuity of a nonconforming \(\mathcal {P}_1\) finite element function. Finally, we present a numerical example to show our proposed method works well.