  We show that for dynamically convex contact forms in three dimensions, the
cylindrical contact homology differential d can be defined by directly counting
holomorphic cylinders for a generic almost complex structure, without any
abstract perturbation of the Cauchy-Riemann equation. We also prove that d^2 =
0. Invariance of cylindrical contact homology in this case can be proved using
S^1-dependent almost complex structures, similarly to work of Bourgeois-Oancea;
this will be explained in another paper.
