CoInvestigator(Kenkyūbuntansha) 
ODA Takayuki Grad. Sch. of Math. Sci., The University of Tokyo, Prof., 大学院・数理科学研究科, 教授 (10109415)
OSHIMA Toshio Grad. Sch. of Math. Sci., The University of Tokyo, Prof., 大学院・数理科学研究科, 教授 (50011721)

Budget Amount *help 
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1999 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1998 : ¥900,000 (Direct Cost : ¥900,000)

Research Abstract 
In this academic year, I have been studied mainly on degenerate principal series of real reductive Lie groups and obtained the following. We consider a maximal parabolic subgroup of SO(m, n) (resp. U(m, n)) such that its Levi part is isomorphic to SO(m  n) x GL(n,R) (resp. U(m  n) x GL(n, C)). We consider the representations of SO(m, n) (resp, U(m, n)) induced from the representations of the parabolic subgroup coming from irreducible finitedimensional representations of SO(m  n) (resp. U(m  n))) and onedimensional representation of GL(n, R) (resp. GL(n, R)). In the last academic year, I found a reducibility of the representation obtained by considering the restriction to SO(m, l) (resp. U(m, 1)). In this year, I obtained an irreducibilty result. For the case of U(m, n) and the "sufficitintly" positive case" of SO(m, n), there is no reducibility other than the above. For the case of SO(m, n), the situation is quite subtle. In fact, Farmar had found an extra reducibility at the most singular parameter for the case of SO(3, 2). Our reducibility is described in terms of Ktype decomposition of the degenerate principal series. It is compatible with the restriction tosmaller SO(m, k) (k < n) and we can obtain branching rule of some derived functor modules which appear as irreducible constituents.
