  In this paper the notion of bisimulation relation for linear
input-state-output systems is extended to general linear differential-algebraic
(DAE) systems. Geometric control theory is used to derive a linear-algebraic
characterization of bisimulation relations, and an algorithm for computing the
maximal bisimulation relation between two linear DAE systems. The general
definition is specialized to the case where the matrix pencil $sE - A$ is
regular. Furthermore, by developing a one-sided version of bisimulation,
characterizations of simulation and abstraction are obtained.
