A Qualitative Bigraph Model for Indoor Space

Formal models of indoor space for reasoning about navigation tasks should capture key static and dynamic properties and relationships between agents and indoor spaces. This paper presents a method for formally representing indoor environments, key indoor events that occur in them, and their effects on the topological properties and relationships between indoor spaces and mobile entities. Based on Milner’s bigraphical models, our indoor bigraphs provide formal algebraic specifications that independently represent agent and place locality (e.g., building hierarchies) and connectivity (e.g., path based navigation graphs). We illustrate how the model supports the description of scenes and narratives with incomplete information, and provide a set of reaction rules dictating legal system transformations to support goal-directed navigation. Given a starting scene and a particular navigation task we can determine potential sequences of events satisfying a goal (e.g., if a building fire occurs, what actions can an agent take to reach an exit?).