Fig. 4

FLAME GPU state diagram for the collection implementation of pairwise cell interaction model. The diagram shows the order of agent functions (black rectangles) and interactions between agents via message lists (coloured rhombuses) through a single iteration of the main simulation loop. Within a layer, indicated by blue dashed boxes, functions may execute concurrently. In the first function layer, AC agents output their publicly visible information to the quantity message list. This information includes the type and quantity of A which the AC agent represents. B agents then execute the B Interact function in the second layer. Each B agent iterates the message list, attempting to interact with AC agents where appropriate. This depends on their being sufficient quantity for an interaction to occur, implemented using atomic operations on the message data. Finally, in the third layer once all possible interactions have occurred, AC agents iterate the modified quantity message list to find the message they originally output, and update their local data such as quantity to match the modified message data