English

Symmetry defect of $n$-dimensional complete intersections in $\mathbb{C}^{2n-1}$

Algebraic Geometry 2024-04-30 v1 Differential Geometry

Abstract

Let X,YC2n1X, Y \subset \mathbb{C}^{2n-1} be nn-dimensional strong complete intersections in a general position. In this note, we consider the set of midpoints of chords connecting a point xXx \in X to a point yYy \in Y. This set is defined as the image of the map Φ(x,y)=x+y2.\Phi(x,y)=\frac{x+y}{2}. Under geometric conditions on XX and YY, we prove that the symmetry defect of XX and YY, which is the bifurcation set B(X,Y)B(X,Y) of the mapping Φ\Phi, is an algebraic variety, characterized by a topological invariant. We introduce a hypersurface that approximates the set B(X,Y)B(X,Y) and we present an estimate for its degree. Moreover, for any two nn-dimensional strong complete intersections X,YC2n1X,Y\subset \mathbb{C}^{2n-1} (including the case X=YX=Y) we introduce a generic symmetry defect set B~(X,Y)\tilde{B}(X,Y) of XX and YY, which is defined up to homeomorphism.

Keywords

Cite

@article{arxiv.2404.18927,
  title  = {Symmetry defect of $n$-dimensional complete intersections in $\mathbb{C}^{2n-1}$},
  author = {L. R. G. Dias and Z. Jelonek},
  journal= {arXiv preprint arXiv:2404.18927},
  year   = {2024}
}
R2 v1 2026-06-28T16:10:10.958Z