A survey around the Hodge, Tate and Mumford-Tate conjectures for abelian   varieties
  This survey describe Hodge, Tate and Mumford-Tate conjectures for abelian varieties. After some preliminaries on endomorphism ring, polarization and algebraic cycles, we state the three conjectures and provide a list of know results. Finally, we explain some links between these conjectures. 
Victoria Cantoral Farf\'an
math.NT