1. Modeling Interaction: Predator-Prey and Beyond CS 170: Computing for the Sciences and Mathematics

2. Administrivia Last time  Modeling Competition Today  Modeling Interaction in General  HW #4 Due!

3. Competition: One Type of Interaction Competition:  “births” for both populations were independent growth  “deaths” were proportional to a constant times BOTH populations Interaction  Some event that occurs between two stocks. In the competition model, these interactions were always negative for both parties

4. Interaction Constant Interaction constant k  Can represent a number of things  Chance of interaction  Combination of two chances Chance of interaction times chance of “thing” happening  Could also include a “magnitude” i.e. “How many things does it effect”

5. Positive Interaction Example: Food supply  If it is high, likely good for population

6. Predator-Prey Model Predator  Negative impact on prey Prey  Positive impact on Predator

7. Interactions Can Mean a Lot of Things SIR Model for disease spread Susceptibles Infecteds Recovereds Infection (flow between S and I) depends on an interaction of S and I.

8. HOMEWORK! READ Module 6.2 and 6.4 in the textbook Homework 5  Create models of Zombie infection  Due next Monday, October 11 th NEXT CLASS IN P115