## Beyond endoscopy and geometric terms

James Arthur

University of Toronto

October 1, 2016

Beyond Endoscopy is the proposal by Langlands for using the trace formula to attack the Principle of Functoriality. Many of the problems at this (early) stage concern the geometric terms in the trace formula. Most immediate perhaps is to extend Altug's application of Poisson summation from $\mathrm{GL}(2)$ to more general groups. One could then try to identify the contribution of the nontempered representations on the spectral side to the resulting Fourier transforms of geometric terms.