  This paper introduces a conception that any weighted directed network
topology is almost decouplable, which can help to transform the topology into a
similar form being composed of uncoupled vertices, and thus reduce the
complexity of analysis for networked dynamical systems. As an example of its
application, the consensus problem of linear multi-agent systems with
time-varying network topologies is addressed. As a result, a necessary and
sufficient condition for uniform consensus is proposed.
