On the 0-dimensional irreducible components of the singular locus of $\Cal A_g$

V. Gonzalez -Aguilera, J. M. Munoz-Porras, Alexis G. Zamora

In this short note we give a characterization of extremal principally polarized abelian varieties determining an isolated point in $Sing \Cal A_g$. The case $g=5$ is treated with d…