  We present a small x resummation for the GLAP anomalous dimension and its
corresponding dual BFKL kernel, which includes all the available perturbative
information and nonperturbative constraints. Specifically, it includes all the
information coming from next-to-leading order GLAP anomalous dimensions and
BFKL kernels, from the constraints of momentum conservation, from
renormalization-group improvement of the running coupling and from gluon
interchange symmetry. The ensuing evolution kernel has a uniformly stable
perturbative expansion. It is very close to the unresummed NLO GLAP kernel in
most of the HERA kinematic region, the small x BFKL behaviour being softened by
momentum conservation and the running of the coupling. Next-to-leading
corrections are small thanks to the constraint of gluon interchange symmetry.
This result subsumes all previous resummations in that it combines optimally
all the information contained in them.
