Transcript Biology: foraging Day 6 COLQ 201 Multiagent modeling Harry Howard Tulane University Course organization  http://www.tulane.edu/~howard/Multiagent/  Photos? 25-Jan-2010 COLQ 201, Prof.

Biology: foraging
Day 6
COLQ 201
Multiagent modeling
Harry Howard
Tulane University
Course organization
 http://www.tulane.edu/~howard/Multiagent/
 Photos?
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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Photos
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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Ants
Models Library > Biology > Ants
(updated version of the one on the
website)
Overview
 Set up the model & turn plotting on.
 Look at the splotches that are not in the
center. Notice how far they are from the
center splotch.
 Run the model & stop it when it stops
changing.
 What is the order in which the splotches
(food sources) are consumed?
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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Ant foraging
 How do ants navigate?
 Now let us experiment: population = 125,
diffusion = 50, evaporation = 10.
 Decrease population to 50 & run. What is the
difference?
 Increase population to 200 & run. What is the
difference?
 Test diffusion at 25 & 75. What is the difference?
 Test evaporation at 5 & 50. What is the difference?
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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AntSystem
has several errors
Programming NetLogo
Models Library > Earth Science >
Fire
Intro to Fire
 Set up
 What do you think the green represents?
 What do you think the red represents?
 What do you think the black represents?
 Run it.
 Experiment
 Lower density to 55. What % burns?
 Raise density to 65. What % burns?
 Set density to 59. What % burns?
 What are the agents?
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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Conclusion
 This is an example of a common feature of
complex systems:
the presence of a non-linear threshold or critical
parameter.
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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How it is programmed
 Switch to the Procedures tab.
 Click on the Procedures pull-down menu. What
procedures do you see?
 fade-embers
 go
 ignite
 setup
 Find each of these in the code.
 What is the relation of setup and go to the
interface?
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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Procedures
 What is the layout of a procedure?
 What does ;; mean?
 What does ask do?
 What does if do?
 What does set do?
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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Turtles & patches
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COLQ 201, Prof. Howard, Tulane University
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Next time
 Biology: migration
Scatter, Randomly walking
25-Jan-2010
COLQ 201, Prof. Howard, Tulane University
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