The problem of controlling the output of a system so as to achieve asymptotic tracking of prescribed trajectories and/or asymptotic re- jection of undesired disturbances is a central problem in control the- ory. A classical setup in which the problem was posed and success- fully addressed - in the context of linear, time-invariant and finite dimensional systems - is the one in which the exogenous inputs, namely commands and disturbances, may range...