This tutorial discusses some powerful techniques which can be used to build artificial intelligent (AI) systems which act rational in the sense of following an overarching goal. AI Principle: Based on the perceived environment, compute actions ( decisions) in order to maximize a long-term return. The actual implementation of this principle requires, of course, to have a precise definition for what is meant by "perceived environment", "actions" and "return". We highlight that those definitions are essentially a design choice which have to be made by an AI scientist or engineer which is facing a particular application domain. Let us consider some application domains where AI systems could be used (beneficially?): - a routing app for Helsinki (similar to https://www.reittiopas.fi/):