Eric Opdam

Abstract:   The spectral decomposition of affine Hecke algebras can be made quite explicit. In particular the tempered spectrum can be classified, and the dependence of the Plancherel measure on the Hecke parameters can be made explicit. From this description it is not hard to derive conditions on the types and parameters of two affine Hecke algebras H_1 and H_2 such that there exists a measure preserving correspondence between the tempered spectra of H_1 and H_2. This idea has a striking application to the classification of the tempered unipotent representations of adjoint, simple p-adic groups (which we assume to be split over an unramified extension of the base field) as given earlier by Lusztig. The method yields a natural extension of Reeder's work on formal degrees and L-packets of unipotent discrete series representations of exceptional groups.

Here are some directions to Northeastern University. Lake Hall and Nightingale Hall can be best accessed from the entrance on the corner of Greenleaf Street and Leon Street. The two halls are connected, with no well-defined boundary in between. In particular, 509 Lake Hall is on the same corridor as 544 Nightingale Hall.

There is free parking available for people coming to the Colloquium at Northeastern's visitor parking (Rennaisance Garage). The entrance is from Columbus Avenue. If coming by car, you should park there and take the parking talon. After the lecture, you may pick up the payment coupon from Andrei Zelevinsky.