Courses/CS 461/Winter 2006/Justin Wu/Week 2

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[edit] Biology - Moths

Emergent phenomenon:
Moths circle around the light source even though none of the rules governing these agents specifies that they should find a light source, then circle it.

Rules:
1) Moths will seek a light source by reading the "presence" of light in a given patch and its neighbors, and heading in that direction, much like the hillclimbing turtle 2) If no light source present, wander at random 3) Moths will evade a light source that is too bright (due to being too close), by turning right or left

Why:
Due to rule 1, the moths will always feel a force directing them to the closest light source (a fixed point), and due to rule 3, they will consistently turn right or left when at a certain distance, resulting in a fixed point rotation around the light source. This is why they circle a light, once found. Rule 2 is present to allow for moths that are nowhere near a light to hopefully "stumble" into one.

[edit] Biology - Ants

Emergent phenomenon:
Although each ant works individually, without any communication to other ants, the colony as a whole seems to work as under a collective conscious, with more and more ants working to bring food from a single food source to the colony.

Rules:
1) Ants wander at random if no food is found 2) If food is found, they will return to colony leaving behind some chemical 3) Ants are directed towards the presence of the chemical through hillclimbing turtle procedure, as with the moths

Why:
The ants will wander at random until food is found (rule 1), at which point they will lay down a chemical trail (rule 2). The more ants that find the trail, the more the trail is strengthened (rule 3), until a large portion of the entire population is traversing back and forth between the food source and the colony.

[edit] Biology - Fireflies

Emergent phenomenon:
Although each firefly flashes based on its own internal clock, as the simulation runs through, the firefly population begins to synchronize their flashes until a significant majority only flashes at the same time.

Rules:
1) Each firefly has an internal clock that tells it when to flash 2) A firefly's clock will attempt to reset itself when triggered by neighbor's flashing 3) A firefly's clock may not reset itself during the cooldown interval

Why:
In the beginning, all fireflies have their own random clocktimes, and so the flashing is very erratic. However, as the simulation progresses, due to rule 2, the fireflies will attempt to reset their clocks in order to align with their neighbors. This effect progresses much like a ripple effect, until a significant portion of the population all have aligned clocks.