I was reading Accesible Independence Results for Peano Arithmetic, Kirby & Paris and saw a symbol (at top of the $\mbox{page 288}$, in $\mbox{Lemma 3.}$) like $\dot{-}$ which I do not know what it means.
It appearing like this:
$\dots$ then $o_{n+1}\left(m\dot{-}1\right)=\langle\alpha\rangle\left(n\right)$.
Any ideas?