Formalising the Common Sense of a Mobile Robot Paulo E. Santos Abstract: Looking at the history of Artificial Intelligence, often theoretical rigor seems inversely proportional to practical applicability. Particularly, in the field of robotics, there is a gap between the research on knowledge representation and practical robotics. In the present paper, a solution for bridging this gap is described and discussed: Shanahan's logical account for a mobile robot. Called ``A Logical Account for the Common Sense Informatic Situation for a Mobile Robot'', this framework involves the assimilation of sensor data, and action planning, through an abduction process on theories about actions and change, and space and shape. An extension of the Event Calculus is taken as the underlying logical system. Actually, these theories are fragments of second-order logic since Circumscription (which is expressed in second-order logic) is used to overcome the frame problem. However, the solution presented to the frame problem does not cope with all of the issues concerned with this problem (since the solution deals only with the persistence problem); moreover, due to the lack of an algorithm capable of automatically constructing theories about the background knowledge, it is impossible to affirm whether the solution presented solves, in a general way, the problem for which it is proposed. Finally, the analysis of the computational complexity of the framework in question made us conclude that, in the general case, its complexity is at least complete for the second level of the polynomial hierarchy.