On the problem of spurious eigenvalues in the approximation of linear elliptic problems in mixed form
On the problem of spurious eigenvalues in the approximation of linear elliptic problems in mixed form
In the approximation of linear elliptic operators in mixed form, it is well known that the so-called inf-sup and ellipticity in the kernel properties are sufficient (and, in a sense to be made precise, necessary) in order to have good approximation properties and optimal error bounds. One might think, in …