1. Social studies: traffic Day 10 COLQ 201 Multiagent modeling Harry Howard Tulane University

2. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University2 Course organization  http://www.tulane.edu/~howard/Multiagent/ http://www.tulane.edu/~howard/Multiagent/

3. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University3 Q1  MIN = 8.0  AVG = 9.7  MAX = 10.0

4. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University4 Explanation  Don't just list observations.  Don't offer a dormitive principle as an explanation.

5. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University5 Q2  MIN = 8.0  AVG = 9.5  MAX = 10.0

6. Traffic Basic Models Library > Social Science

7. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University7 Overview  What are the rules?  A car slows down (decelerates) if it sees a car close ahead.  A car speeds up (accelerates) if it doesn't see a car ahead.  What are the parameters?  Acceleration  Deceleration

8. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University8 Overview, cont.  What are the measures?  Red car speed  The speed of a single car (turtle 0), painted red so it can be watched.  Minimum speed  The slowest speed of any car.  Maximum speed  The fastest speed of any car (this doesn't exceed the speed limit!)

9. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University9 Think about the topic  With a friend …  How would you define a traffic jam?  How do you think a traffic jam forms?

10. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University10 First experiment  Leave everything at the default values and decrease the number of cars to 10.  Run the simulation. (You may want to slow it down.) Is there a traffic jam?  Now gradually increase the number of cars.  When is there the first traffic jam?  17, though it can resove itself.

11. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University11 Concepts  Are traffic jams an emergent phenomenon?  Notice that the number of cars has a threshold or critical value, beyond which the quality of system changes dramatically.  That is, a change in quantity produces a change in quality.  This is practically the definition of a non-linear system.  Sometimes this change in quality is called a phase transition.

12. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University12 Second experiment  Return the number of cars to 20.  Try to find the parameter settings that optimize traffic flow.  Deceleration = 0, produces a constant speed, but with crashes.  Decreasing one & increasing the other can erase the traffic jam.

13. Traffic Grid Models Library > Social Science

14. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University14 Look at it

15. Programming NetLogo

16. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University16 Starting form scratch  http://ccl.northwestern.edu/netlogo/docs/ http://ccl.northwestern.edu/netlogo/docs/

17. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University17 Procedures Models Library > Earth Science > Fire  What is the layout of a procedure?  What does ;; mean?  What does ask do?  What does if do?  What does set do?

18. 3-Feb-2010COLQ 201, Prof. Howard, Tulane University18 Next time  Biology: individual vs. collective movement  Independence vs. mimetism