Time
Representing Temporal Dynamics in Simulations The real world is PARALLEL,
things are happening simultaneously, all at once, It's really not too difficult if we divide time into an endless stream of very small slices or steps. There are several ways to schedule
(poll) agent actions in an artificial world. The granularity of time is important too. Simulations may produce different behaviors when using different representations of time. |
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There are three common ways to represent time: |
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Sequential Scheduling |
Random Scheduling |
Cinematic Scheduling |
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We poll agents in a fixed sequence within each time step. We repeat the sequence in the same order every time. Advantages:
Disadvantages:
Example:
Growth: Diffusion Limited Aggregation. |
We poll agents randomly within each time step or we do away with time steps altogether. Agents rarely follow or are lead by the same agent. Advantages:
Disadvantages:
Example: Shelling's Segregation Model. |
We break time down into frames much like those in a movie film. Within one frame we ask each agent what it would like to do in the next frame. We resolve any unrealistic influences or collisions before we create the next frame. Advantages:
Disadvantages:
Example: Cellular Automata: |
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Cinematic Scheduling is the most Realistic As in a movie film, if the time steps represented by an individual frame are more finely grained than the nuances of behavior we wish to observe, the result will be a appear as smooth and seamless action. Consequently, if we construct time steps in a simulation of a size much smaller than the time slices of behavior we wish to simulate, we can expect a realistically precise simulation. There is evidence that the real world is also divided into indivisible units of space and time. |
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How Cinematic Scheduling Works: To create the visual effect of
a frame-by-frame movie that looks like this...
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