  In this note we compare the a-invariant of a homogeneous algebra B to the
a-invariant of a subalgebra A. In particular we show that if $A \subset B$ is a
finite homogeneous inclusion of standard graded domains over an algebraically
closed field with A normal and B of minimal multiplicity then A has minimal
multiplicity. In some sense these results are algebraic generalizations of
Hurwitz type theorems.
