The document discusses two types of fuzzy inference systems - Mamdani-type and Sugeno-type - that can be used to control a Dynamic Voltage Restorer (DVR) to mitigate voltage sags. It outlines the basic differences between the two systems, including that Mamdani-type FIS has output membership functions while Sugeno-type FIS does not. Both systems were simulated in MATLAB with two inputs (error and change in error) and one output to evaluate their performance in compensating voltage sags.