Referring: - [Introduction to Utility theory](http://www.gameaipro.com/GameAIPro/GameAIPro_Chapter09_An_Introduction_to_Utility_Theory.pdf) - [Dual Utility reasoning](http://www.gameaipro.com/GameAIPro2/GameAIPro2_Chapter03_Dual-Utility_Reasoning.pdf) - [Building utility into behavior trees](http://www.gameaipro.com/GameAIPro/GameAIPro_Chapter10_Building_Utility_Decisions_into_Your_Existing_Behavior_Tree.pdf)
