  Using Gromov-Witten theory the numbers of complex plane rational curves of
degree d through 3d-1 general given points can be computed recursively with
Kontsevich's formula that follows from the so-called WDVV equations. In this
paper we establish the same results entirely in the language of tropical
geometry. In particular this shows how the concepts of moduli spaces of stable
curves and maps, (evaluation and forgetful) morphisms, intersection
multiplicities and their invariance under deformations can be carried over to
the tropical world.
