On the role of the interactor matrix in multiinput-multioutput adaptive control

Recent papers have shown that the system interactor matrix plays an important role in the multiinput-multioutput adaptive control. In these papers, however, the impression may have been inadvertently conveyed that the interactor matrix can be taken to be diagonal in almost all cases. This note shows that this impression is false and that, in general, a nondiagonal interactor matrix should be considered.