Nearing the end, we still have not made the model conform to the last two Constraints. The problem is that we have not yet made a connection from what the yeast are doing to how much water and sugar there is. The simplest way to model this is to consider the division process as a consumer of sugar and water resources. Thus we have the model yeast4.mdl:
And this model conforms to all the Constraints written. But is it a good model? In this case the answer is probably "not yet". For a detailed an accurate representation of yeast growth we would need to get some experimental data, and calibrate the model for temperature and resource deprivation effects. The point about this model is that is does not violate the most obvious common sense Reality Check equations.
We have shown a number of different models. What about the Reality Check equations? Except for the small change made to hot is dead, they are unchanged and have exactly the same diagram.
