Logarithmic equivalence of Welschinger and Gromov-Witten invariants

I. Itenberg, V. Kharlamov, E. Shustin

Published 2004-07-11Version 1

The Welschinger numbers, a kind of a real analog of the Gromov-Witten numbers which count the complex rational curves through a given generic collection of points, bound from below the number of real rational curves for any real generic collection of points. By the logarithmic equivalence of sequences we mean the asymptotic equivalence of their logarithms. We prove such an equivalence for the Welschinger and Gromov-Witten numbers of any toric Del Pezzo surface with its tautological real structure, in particular, of the projective plane, under the hypothesis that all, or almost all, chosen points are real. We also study the positivity of Welschinger numbers and their monotonicity with respect to the number of imaginary points.