Complex sentence: The word "optimal" is to be intended in a strictly mathematical sense, as the synthesised controller will be the one that minimises the effect of system inputs on outputs, which may not be "optimal" in the sense meant by operators.
Split into simpler sentences: The word "optimal" is used strictly in the mathematical sense, as the synthesised controller will be one that minimizes the effect of system inputs on outputs. This may not be seen as "optimal" in the sense meant by operators.