With respect to whom are you critical?

Jin-ichi Itoh, Costin Vîlcu, Tudor Zamfirescu

For any compact Riemannian surface $S$ and any point $y$ in $S$, $Q_y^{-1}$ denotes the set of all points in $S$, for which $y$ is a critical point. We proved \cite{BIVZ} together…