The H∞ optimal control problem in a behavioral setting

The general H8 control problem has been formalized in a behavioral setting and it is shown that H8 optimal controllers can be synthesized using J-spectral factorizations. The idea to view control as restricting the interconnection variables of a system turns out to be a useful starting point for the formulation and solution of an H8 control problem, which departs from the prevailing input-output formalization of this problem. The results of this paper provide a conceptual advantage in that no assumptions are made on input-output decompositions of variables or on the causality structure of plant and controlle