Garbage Ants

There are blue ants (that produce garbage) and red ants (that collect garbage into clusters). All ants just walk randomly, and blue ants have a certain probability of producing garbage after each step.

The red ant behavior is more interesting (it is inspired by a behavior described in Mitchel Resnick's book "Turtles, Termites, and Traffic Jams") . When a red ant sees a piece of garbage:

• if it's already carrying a piece of garbage, it drops the one it's carrying next to the one it saw on the ground;
• if it's not carrying anything, it picks it up.

The remarkable property of the red ant algorithm is that, although ants do not coordinate their actions, pieces of garbage are progressively gathered into clusters.

Most parameters of the GUI should be self-explanatory. The turn probability is the probability, at each step, that an ant makes a 45 degree turn. The higher it is, the more time it takes for an ant to travel long distances. In the same way, the litter probability is the probability, at each step, that a blue ant produces a new piece of garbage. It should be kept fairly low, or the red ants will be overwhelmed. The passive steps parameter of the red ant behavior is very important. When it's high, it's easier for red ants to break a cluster into pieces and move them to a another cluster. When it's low, clusters are more compact and more resistant. A right balance can make the process of collecting garbage into clusters more efficient by facilitating the breakdown of small clusters while keeping bigger clusters more compact.

You can download the application (garbageAnts.jar), which has more control parameters than the applet (try java -jar garbageAnts.jar -help).

Michel Charpentier <>