Artificial Immune Systems

These two case studies model populations of immune-system cells that can interact with other cells that have complementary shapes to their own. Each cell maintains an activation level, which slowly decreases over time. When a cell encounters another cell with a complementary shape, its activation level increases by an amount related to the similarity in shape of the two cells. If a cell's activation level reaches zero, it dies and is removed from the simulation.

Shapespace is based on the model described in Hart and Ross's Studies on the Implications of Shape-Space Models for Idiotypic Networks. The visualisation shows shape space rather than physical space, with cells coloured according to their activation level. Each point in shape space has a complementary region in which cells will be activated. From a random initial state, the system quickly develops "tolerant" and "intolerant" regions as an emergent behaviour.

Grid extends the model to support cells that not only have a shape but also move around in discretised physical space. The visualisation shows physical space and two live charts: a histogram showing the age distribution of the cells, and a line chart showing the total population. In this model, we see population explosions as groups of mutually-reinforcing cells come into contact.