We currently add both a symmetry constraint $p{i+1}=p{N-i}$ and a decreasing constraint $p_{i+1}<p_i$
for $i<\frac N2$. While not strictly necessary to find the solution, they may speed up the computation. We are unsure though because of #7.
Another option is to remove $p_i$ for $i>\frac N2$ altogether as variables.
We currently add both a symmetry constraint $p{i+1}=p{N-i}$ and a decreasing constraint $p_{i+1}<p_i$ for $i<\frac N2$. While not strictly necessary to find the solution, they may speed up the computation. We are unsure though because of #7.
Another option is to remove $p_i$ for $i>\frac N2$ altogether as variables.