English

Relations ab\'eliennes des tissus ordinaires de codimension arbitraire

Differential Geometry 2022-01-03 v2

Abstract

We generalize to webs of any codimension results already known in codimension one. Given a holomorphic dd-web W\cal W of codimension qq (qn1)(q\leq n-1) in an ambiant nn-dimensional holomorphic manifold UU, we define for any integer pp (1pq)(1\leq p\leq q) the condition for such a web to be \emph{pp-ordinary} ((resp. \emph{strongly pp-ordinary})). If this condition is satisfied, we then prove that its pp-rank rp(W)r_p({\cal W}) (\bigl(resp. its closed pp-rank r~p(W))\widetilde r_p({\cal W})\bigr), i.e. the maximal dimension of the vector space of the germs of pp-abelian relations ((resp. of closed pp-abelian relations)) at a point mm of UU, is finite. We then give an upper-bound πp0(n,d,q)\pi_p^0(n,d,q) (\bigl(resp. πp(n,d,q))\pi'_p(n,d,q)\bigr) for these ranks. Moreover, for some values of dd, and we then say then that the web is \emph{pp-calibrated} ((resp. \emph{strongly pp-calibrated})), we define a tautological holomorphic connection on a holomorphic vector bundle of rank πp0(n,d,q)\pi_p^0(n,d,q) (\bigl(resp. πp(n,d,q))\pi'_p(n,d,q)\bigr), for which the sections with vanishing covariant derivative may be identified with pp-abelian relations ((resp. closed pp-abelian relations)). The curvature of this connection is then an obstruction for the rank rp(W)r_p({\cal W}) (\bigl(resp. r~p(W))\widetilde r_p({\cal W})\bigr) to be maximal. The main change is the correction of a mistake ((proposition 4, section 6-5)) in the first version : the 1-rank of the concerned web is not 0 as we claimed, but 1. However, the important corollary remains true : even at the level of germs, some 2-abelian relation exhibited by Goldberg in [G] [G] on some web of codimension 2 in an ambiant space of dimension 4, is the coboundary of none 1-abelian relation. The section 7, devoted to this correction, is self content, not depending on the previous results of the paper.

Keywords

Cite

@article{arxiv.1712.00997,
  title  = {Relations ab\'eliennes des tissus ordinaires de codimension arbitraire},
  author = {Daniel Lehmann},
  journal= {arXiv preprint arXiv:1712.00997},
  year   = {2022}
}

Comments

20 pages, in French