  This paper studies scale-free protocol design for H_\infty almost output and
regulated output synchronization of heterogeneous multi-agent systems with
linear, right-invertible, and introspective agents in presence of external
disturbances. The collaborative linear protocol designs are based on localized
information exchange over the same communication network, which do not require
any knowledge of the directed network topology and spectrum of the associated
Laplacian matrix. Moreover, the proposed scale-free protocols achieve H_\infty
almost synchronization with a given arbitrary degree of accuracy for any size
of the network.
