In this book on Game Theory, on page 186,I do not understand the very end of the page:
[T]he incentive to deviate$-$the left hand side of equation 5.18$-$ is $0$ in first order of $\epsilon$, so that preventing deviations require only a probability of punishment that is $0$ to first order as well.
Can someone clarify to me what is meant technically by these two sentences separately, and also why it is the case that they hold?