DEX (Decision EXpert) and its successor DEXi (Decision Expert For Education) are methods for multi-criteria decision analysis (MCDA). Methods are developed by a research team led by Bohanec, Bratko, and Rajković. DEXi works with the utility functions (decision rules). These rules are defined by the user on the software. It is a very easy and effective method. DEX and DEXi are used in the fields of agriculture, and hydropower.