# Inter-Species Dynamics

The Lotka-Volterra model representation challenge was discussed earlier as a goal for our lab in preparation for Engineering Week, culminating in a set of demonstrations to be given on February 22, 2014. The image shown is a partial screen shot of a simulation created by Karen Doore, a PhD student in Computer Science, also working in the Creative Automata Lab. The time-based dynamics of predator-prey are seen on the right hand side and may look familiar to most modelers of ecological systems where predators and prey interact, causing the population levels to oscillate. The diagram on the left differs from the representational norm--it is an interactive Javascript sketch of an analog water computer. The water computer stems from an underlying modeling language formalism called System Dynamics. Water levels depict the predator and prey populations rising and falling. Input and output valve settings are a function of population levels sensed with water floats. The equations are also represented in a way that the coefficients change inside the equation text, but not shown in this figure due to lack of space. Here are the implemented equations:

$\frac{dP}{dt} = -Pm + bHP ; \frac{dH}{dt} = Hr - aHP$