Termites

What is it?

This project is inspired by the behavior of termites gathering wood chips into piles. The termites follow a set of simple rules. Each termite starts wandering randomly. If it bumps into a wood chip, it picks the chip up, and continues to wander randomly. When it bumps into another wood chip, it finds a nearby empty space and puts its wood chip down. With these simple rules, the wood chips eventually end up in a single pile.

How to Use It

Click the `setup` button to set up the termites (red) and wood chips (yellow). Click the `go` button to start the simulation. The `number` slider controls the number of termites. (Note: Changes in the `number` slider do not take effect until the next `setup`.) The `density` slider controls the initial density of wood chips. |

Things to Notice

As piles of wood chips begin to form, the piles are not "protected" in any way. That is, termites sometimes take chips away from existing piles. That strategy might seem counter-productive. But if the piles were "protected", you would end up with lots of little piles, not one big one.

In general, the number of piles decreases with time. Why? Some piles disappear, when termites carry away all of the chips. And there is no way to start a new pile from scratch, since termites always put their wood chips near other wood chips. So the number of piles must decrease over time. (The only way a "new" pile starts is when an existing pile splits into two.)

This project is a good example of a DECENTRALIZED strategy. There is no termite in charge, and no special pre-designated site for the piles. Each termite follows a set of simple rules, but the colony as a whole accomplishes a rather sophisticated task.

Explorations

- Do the results change if you use just a single termite? What if you use several thousand termites?

- When there are just two piles left, which of them is most likely to "win" (as the single, final pile)? How often does the larger of the two piles win? If one pile has only a single wood chip, and the other pile has the rest of the wood chips, what are the chances that the first pile will win?

StarLogo Features
Notice that the wood chips do not exist as objects. They are just represented as colors in the patches. The termites update the patch colors as they pick up and put down the wood chips. In effect, the screen is being used as the data structure. This strategy is useful in many StarLogo programs.

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