We show that every analytic set in the Baire space which is dominating
contains the branches of a uniform tree, i.e. a superperfect tree wit
h the property that for every splitnode all the successor splitnodes h
ave the same length. We call this property of analytic sets u-regulari
ty. However, we show that the concept of uniform tree does not suffice
to characterize dominating analytic sets in general. We construct a d
ominating closed set with the property that for no uniform tree whose
branches are contained in the closed set, the set of these branches is
dominating. We also show that from a SIGMA(n+1)1-rapid filter a non-u
-regular PI(n)1-set can be constructed. Finally, we prove that SIGMA2(
1)-K(sigma)-regularity implies SIGMA2(1)-u-regularity.