. We consider finite element approximations of unique continuation problems subject to elliptic equations in the case where the normal derivative of the exact solution is known to reside in some finite dimensional space. To give quantitative error estimates we prove Lipschitz stability of the unique continuation problem in the global \ (H¹\) -norm. This stability is then leveraged to derive optimal a posteriori and a priori error estimates for a primal-dual stabilized finite element method. Keywordsunique continuationconditional stabilityfinite dimensionNeumann boundaryfinite element methodsstabilized methodserror estimatesMSC codes65N20
Burman et al. (Tue,) studied this question.