English

Indices of 1-forms on an isolated complete intersection singularity

Algebraic Geometry 2016-09-07 v2

Abstract

There are some generalizations of the classical Eisenbud-Levine-Khimshashvili formula for the index of a singular point of an analytic vector field on RnR^n for vector fields on singular varieties. We offer an alternative approach based on the study of indices of 1-forms instead of vector fields. When the variety under consideration is a real isolated complete intersection singularity (icis), we define an index of a (real) 1-form on it. In the complex setting we define an index of a holomorphic 1-form on a complex icis and express it as the dimension of a certain algebra. In the real setting, for an icis V=f1(0)V=f^{-1}(0), f:(Cn,0)(Ck,0)f:(C^n, 0) \to (C^k, 0), ff is real, we define a complex analytic family of quadratic forms parameterized by the points ϵ\epsilon of the image (Ck,0)(C^k, 0) of the map ff, which become real for real ϵ\epsilon and in this case their signatures defer from the "real" index by χ(Vϵ)1\chi(V_\epsilon)-1, where χ(Vϵ)\chi(V_\epsilon) is the Euler characteristic of the corresponding smoothing Vϵ=f1(ϵ)BδV_\epsilon=f^{-1}(\epsilon)\cap B_\delta of the icis VV.

Keywords

Cite

@article{arxiv.math/0105242,
  title  = {Indices of 1-forms on an isolated complete intersection singularity},
  author = {Wolfgang Ebeling and Sabir M. Gusein-Zade},
  journal= {arXiv preprint arXiv:math/0105242},
  year   = {2016}
}

Comments

19 pages