Functoriality and algebraic cycles

Abstract: I will discuss the following question: is Langlands functoriality given by algebraic cycles? After a survey of some examples of interest, the talk will focus mostly on one case, namely that of inner forms GL(2) over a totally real field. In this case, we can show that functoriality is given by something close to an absolute Hodge cycle; moreover, there is some hope of doing even better. (Joint work with Atsushi Ichino.)