Biology: foraging Day 6 COLQ 201 Multiagent modeling Harry Howard Tulane University 25-Jan-2010COLQ 201, Prof. Howard, Tulane University2 Course organization Photos? 25-Jan-2010COLQ 201, Prof. Howard, Tulane University3 Photos Ants Models Library > Biology > Ants (updated version of the one on the website) 25-Jan-2010COLQ 201, Prof. Howard, Tulane University5 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-2010COLQ 201, Prof. Howard, Tulane University6 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? AntSystem has several errors Programming NetLogo Models Library > Earth Science > Fire 25-Jan-2010COLQ 201, Prof. Howard, Tulane University9 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-2010COLQ 201, Prof. Howard, Tulane University10 Conclusion This is an example of a common feature of complex systems: the presence of a non-linear threshold or critical parameter. 25-Jan-2010COLQ 201, Prof. Howard, Tulane University11 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-2010COLQ 201, Prof. Howard, Tulane University12 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-2010COLQ 201, Prof. Howard, Tulane University13 Turtles & patches 25-Jan-2010COLQ 201, Prof. Howard, Tulane University14 Next time Biology: migration Scatter, Randomly walking