Abstract|The problem of reaching consensus in multiagent second-order systems without a
spanning outgoing tree in the dependency digraph is considered. A theorem stating that the
asymptotic behavior of the system is uniquely determined by the eigenprojector of the Laplacian
matrix of the dependency digraph is proved. The earlier results established by the author and
by Ren and Atkins in their papers are further generalized. For the case in which the dependency
digraph contains no spanning outgoing tree, a regularization method is proposed.