Software and Computer Engineering

Emergent Behavior of Composite Systems

Complex behaviors of systems are one of the most fascinating things in science. By understanding how existing systems work, we aim to predict behavior and hopefully design an useful mechanisms, leveraging the modeled behaviors.

What I find even more fascinating is when the properties of the aggregate do not stem, at least in an obvious manner, from the properties of the individual components. These situations illustrate how our intuition is not foolproof and how we often misjudge system behavior even when the individual behavior is know, and vice-versa.

Conway's Game of Life

The Game of Life, as described by the mathematician John Conway, is a classic example of how complex behavior can emerge from seemly simple rules at an individual level.

It goes as follows: Let there be an infinite 2-dimensional grid of cells, where each cell might be either alive or dead. The game proceeds in turns, advancing the state of the grid according to the last grid state and a small set of rules. Note the 8 closest cells are called the neighbors of a cell. The rules go as follows:

The Wikipedia page has a number of animations showing behavior of some initial states: It it not obvious at all that this set of rules would lead to these observed behavior.

Other examples