  Let F be a non-archimedean local field, let L be the maximal unramified
extension of F, and let fr be the Frobenius automorphism. Let G be a split
connected reductive group over F, and let B(1) be the Bruhat-Tits building
associated to G(F). We know that fr acts on G(L) with fixed points G(F). Let I
be the Iwahori associated to a chamber in B(1). We have the relative position
map, inv, from G(L)/I x G(L)/I to the extended affine Weyl group, W_e of G. If
w is in W_e and b is in G(L), then the affine Deligne-Lusztig set Xw(b fr) is
{x in G(L)/I : inv(x,b fr(x)) = w}. This paper answers the question of which
Xw(b fr) are non-empty for certain G and b.
