Rayleigh–Ritz approximation of the inf-sup constant for the divergence

A numerical scheme for computing approximations to the inf-sup constant of the divergence operator in bounded Lipschitz polytopes in \mathbb R^nis proposed. The method is based on a conforming approximation of the pressure space based on piecewise polynomials of some fixed degree k\geq 0 The scheme can be viewed as a Rayleigh–Ritz method and it gives monotonically decreasing approximations of the inf-sup constant under mesh refinement....