We propose a relative trace formula approach and state the corresponding
fundamental lemma toward the global restriction problem involving Bessel or
Fourier-Jacobi periods of unitary groups UnβΓUmβ,
extending the work of Jacquet-Rallis for m=nβ1 (which is a Bessel period). In
particular, when m=0, we recover a relative trace formula proposed by Flicker
concerning Kloosterman/Fourier integrals on quasi-split unitary groups. As
evidence for our approach, we prove the fundamental lemma for
UnβΓUnβ in positive characteristics.Comment: 55 page