1) At some point the article says:

> Hopefully by the end of this post, you’ll see how all of these diagrams:

which is not a sentence.

2) You write:

> Incentive proportionate selection is

> $$ \frac{\varphi_A(a,b)}{\varphi_A(a,b) + \varphi_B(a,b)},$$

This sentence is of the general form

> Some undefined term is

> $$\int^{ome} c_{omplicated} {f(ormula)}$$

So, it's not very clear, especially because you don't say what $\varphi_A(a,b)$ and $\varphi_B(a,b)$ are.

Since I'm experienced at reading mathematical prose, I can make guesses. I can guess that maybe "incentive proportionate selection" is the name for some particular _form_ of "incentive function".

Are $\varphi_A(a,b)$ and $\varphi_B(a,b)$ just arbitrary functions of $a$ and $b$?

3) A bit before this, you said an incentive function is a function that "controls the selective process". I don't know what "controls the selective process" means. It would probably be good to explain that an incentive function is a real-valued function of the types $a$ and $b$ (if that's correct), and then say a bit about what it does.