M-Accretive Realisations of Skew-Symmetric Operators

Abstract

We consider skew-symmetric operators $A_{0}$ on a Hilbert space $H$ and characterise all (nonlinear) m-accretive restrictions of $A:=-A_{0}^{\ast}$ in terms of the "deficiency spaces" $\ker(1\pm A)$. The results are illustrated by several examples and applied to a partial differential equation with an impedance type boundary condition.