Cycles Representing The Top Chern Class of the Hodge Bundle on the   Moduli Space of Abelian Varieties
  We give a generalization to higher genera of the famous formula $12 \lambda=\delta$ for genus 1. We also compute the classes of certain strata in the Satake compactification as elements of the push down of the tautological ring. 
Torsten Ekedahl and Gerard van der Geer