A_6 is of general type -- Samuel Grushevsky, March 25, 2005
We construct a new effective geometric divisor on A_g (the moduli space of principally polarized complex abelian varieties) and use it to show that A_6 is of general type. Since the work of Tai, Mumford, Clemens, Donagi, etc. in the 1980s, this has remained the only g for which the Kodaira dimension of A_g was unknown. This is joint work with David Lehavi.