Systems with Incommensurate Delays

Unlike for those systems with commensurate delays, stability analysis for systems with incommensurate delays proves far more difficult. In particular, most of the results known to date are sufficient conditions, and seldom are they nonconservative. Necessary and sufficient conditions are scarce and are hardly computable; indeed, many such results merely fall into a restatement-in one form or another-of the definition of stability, thus rendering the conditions of little use. The reader will quickly find out that this lack of strong results is by no means coincidental.