  In this paper, we propose a minimum set of concepts and signals needed to
track the social state during Human-Robot Interaction. We look into the problem
of complex continuous interactions in a social context with multiple humans and
robots, and discuss the creation of an explainable and tractable
representation/model of their social interaction. We discuss these
representations according to their representational and communicational
properties, and organize them into four cognitive domains (scene-understanding,
behaviour-profiling, mental-state, and dialogue-grounding).
