Logic

Just like in any cellular automaton, a set of rules must be established for each cell to specifically recognize their inputs and subsequently produce a desired output in a consistent fashion. We chose a particular set of rules, described in the truth table below, where QL is the present state of the left neighbor cell, QT is the present state of the cell being investigated, QR is the present state of the right neighbor cell, and QT+1 is the next state of the investigated cell, determined by the pace of the gas clock.

We found that these rules were simple enough to be implemented into a biological system and were computationally interesting. As can be seen in the simulation below, when a single cell is stimulated and changed into the “ON” state, this change in state will propagate itself around the circular cellular automaton one cell at a time in a clockwise orientation. When two neighbor cells are initially stimulated, an ever-growing and chaotic pattern arises that engulfs the entire cellular automaton, demonstrating how each cell within the system, made aware of its surroundings, can react in a predictable and contrasting way.

There are many functions that could have been used to execute these truth table rules. We devised a very simple function that allowed for a significant decrease in the number of logic gates, as seen in the diagram below.