Standard vs. Reduced Genus-One Gromov-Witten Invariants

We give an explicit formula for the difference between the standard and reduced genus-one Gromov-Witten invariants. Combined with previous work on geometric properties of the latter, this paper makes it possible to compute the standard genus-one GW-invariants of complete intersections. In particular, we obtain a closed formula for the genus-one GW-invariants of a Calabi-Yau projective hypersurface and verify a recent mirror symmetry prediction for a sextic fourfold as a special case.