This article deals with a
multivalued differential-boundary operator on a nondense domain regarding it as a
linear relation. The adjoint relation is derived. It is shown that these dual relations
have the same form as exhibited in earlier papers where the operators involved were
uniquely defined on dense domains. Self-adjoint relations are considered on the
Hilbert space ℒn2[0,1]. The connection with self-adjoint operators defined on
subspaces of ℒn2[0,1] is made.