"Problem solving." . . . "On the accuracy of least squares methods in the presence of corner singularities"@en . "On the accuracy of least squares methods in the presence of corner singularities" . . . . . . . . . . . . . . . . . . . . . "Finite element method." . . . . "Sobolev space." . . "Singularity (Mathematics)" . . "Elliptic differential equations." . . "Least squares method." . .