Initially a "group navigation state-of-the-art report" (github.com/cloderic/Group-navigation-state-of-the-art-report) written and published here in the fall on 2011 while I was working at Golaem (golaem.com), this article was reworked and published as a part of the Hierarchical Architecture for Group Navigation Behaviors chapter of Game AI Pro 2 (www.gameaipro.com).
The full pdf can be downloaded there (www.cloderic.com/content/2015-06-10-hierarchical-architecture-for-group-navigation-behaviors/GameAIPro2_Chapter20_Hierarchical_Architecture_for_Group_Navigation_Behaviors.pdf).