  The Welschinger invariants of real rational algebraic surfaces are natural
analogues of the genus zero Gromov-Witten invariants. We establish a tropical
formula to calculate the Welschinger invariants of real toric Del Pezzo
surfaces for any conjugation-invariant configuration of points. The formula
expresses the Welschinger invariants via the total multiplicity of certain
tropical curves (non-Archimedean amoebas) passing through generic
configurations of points, and then via the total multiplicity of some lattice
path in the convex lattice polygon associated with a given surface. We also
present the results of computation of Welschinger invariants, obtained jointly
with I. Itenberg and V. Kharlamov.
