So if I have some quantity bounded i.e $ 1-N \leq (p^i-p^{i+1}) \leq N-1,$ for $N\ge1 $. The quantity $p^i-p^{i+1}$ will be an integer as well.
I was trying to figure out how to pose the constraint so that if I have binary variable $b_i$, then $ b_i=\begin{cases} 0 & (p^i-p^{i+1}) =0 \\ 1 & (p^i-p^{i+1}) >0 \end{cases} $
I attempted to pose it as
$\begin{align} b_i \geq (p^i-p^{i+1})\\ M(p^i-p^{i+1}) \geq b_i, \end{align}$
for a large value of $M$ but this does not seem to be exactly what I'm looking for since the quantiy $(p^i-p^{i+1})$ could be negative.
Any suggestions would be greatly appreciated how to properly represent this constraint.
