## F. Kassel and T. Kobayashi, *Stable spectrum for pseudo-Riemannian
locally symmetric spaces*, C. R. Math. Acad. Sci. Paris **349** (2011),
no. 1-2, 29-33, DOI:
10.1016/j.crma.2010.11.023..

Let *X* = *G*/*H* be a reductive symmetric space with rank *G*/*H* = rank *K*/*K* ∩ *H*, where *K* (resp.*K* ∩ *H*) is a maximal compact subgroup of *G* (resp. of *H*).
We investigate the discrete spectrum of certain Clifford-Klein forms Γ\*X*, where Γ is a discrete subgroup of *G* acting properly discontinuously and freely on *X*: we construct an infinite set of joint eigenvalues for ''intrisic'' differential operators on Γ\*X*, and this set is stable under small deformations of Γ in *G*.

[
preprint version(pdf) |
full text(pdf) |
full paper ]

© Toshiyuki Kobayashi