1. Introduction
Since the invention of fuzzy sets and fuzzy systems by Zadeh four decades ago, fuzzy systems have been successfully applied in many different areas. These successes are grounded on the advantages of fuzzy systems [1]–[7]. Firstly, fuzzy systems can be identified by combining human knowledge and information from data. Secondly, the transparency and interpretability of fuzzy rules and systems make them easy to understand and use in applications. Lastly, fuzzy systems are universal approximators, that is, they can approximate any continuous nonlinear function to any degree of accuracy and therefore can be used in the solution of general complex and nonlinear problems.