Proceedings of the London Mathematical Society Advance Access published online on August 17, 2009
Proceedings of the London Mathematical Society, doi:10.1112/plms/pdp027
© 2009 London Mathematical Society
Harmonic analysis on a finite homogeneous space
Dipartimento MeMoMat
Università degli Studi di Roma "La Sapienza"
via A. Scarpa 8
00161 Roma
Italy
Dipartimento di Matematica
Università Roma TRE
L. San Leonardo Murialdo 1
00146 Roma
Italy
tolli@mat.uniroma3.it
Received 26 January 2007. Revision received 9 June 2008. Accepted 9 June 2008.
In this paper, we study harmonic analysis on finite homogeneous spaces whose associated permutation representation decomposes with multiplicity. After a careful look at Frobenius reciprocity and transitivity of induction, we introduce three types of spherical functions. Then we consider the composition of two permutation representations, giving a noncommutative generalization of the Gelfand pair associated to the ultrametric space; actually, we study the more general notion of crested product. Finally, we consider the exponentiation action, generalizing the decomposition of the Gelfand pair of the Hamming scheme; actually, we study a more general construction that we call wreath product of permutation representations, suggested by the study of finite lamplighter random walks. We give several examples of concrete decompositions of permutation representations and several explicit rules of decomposition.
2000 Mathematics Subject Classification 43A95 (primary), 20C15, 20C30, 20E22, 43A90 (secondary).