On embeddings of minimum dimension of PG(n,q)×PG(n,q)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{PG}}(n,q

A construction is given of an embedding of \({\mathrm{PG}}(n-1,q)\times {\mathrm{PG}}(n-1,q)\) into \({\mathrm{PG}}(2n-1,q)\), i.e. of minimum dimension, and it is shown that the image is a nonsingular hypersurface of degree \(n\). The construction arises from a scattered subspace with respect to a Desarguesian spread in \({\mathrm{PG}}(2n-1,q)\). By construction there are two systems of maximum subspaces (in this case \((n-1)\)-dimensional) which cover this hypersurface. However, unlike the standard Segre embedding, the minimum embedding constructed here allows another \(n-2\) systems of maximum subspaces which cover this embedding. We describe these systems and study the stabiliser of these embeddings. The results can be considered as a generalization of the properties of the hyperbolic quadric \(Q^+(3,q)\).

[1]  Michel Lavrauw,et al.  On linear sets on a projective line , 2010, Des. Codes Cryptogr..

[2]  Guglielmo Lunardon,et al.  Blocking Sets and Derivable Partial Spreads , 2001 .

[3]  William M. Kantor,et al.  Linear groups containing a singer cycle , 1980 .

[4]  Michel Lavrauw,et al.  On the isotopism classes of finite semifields , 2008, Finite Fields Their Appl..

[5]  Corrado Zanella,et al.  On linear morphisms of product spaces , 2003, Discret. Math..

[6]  M. Lavrauw Finite semifields with a large nucleus and higher secant varieties to Segre varieties , 2011 .

[7]  Michel Lavrauw,et al.  Scattered Linear Sets and Pseudoreguli , 2013, Electron. J. Comb..

[8]  Giuseppe Marino,et al.  Fq-pseudoreguli of PG(3, q3) and scattered semifields of order q6 , 2011, Finite Fields Their Appl..

[9]  Michel Lavrauw,et al.  Scattered spaces with respect to spreads, and eggs in finite projective spaces : Scattered subspaces with respect to spreads, and eggs in finite projective spaces , 2001 .

[10]  John Sheekey,et al.  Orbits of the stabiliser group of the Segre variety product of three projective lines , 2014, Finite Fields Their Appl..

[11]  Michel Lavrauw,et al.  Segre embeddings and finite semifields , 2014, Finite Fields Their Appl..

[12]  Michel Lavrauw,et al.  Scattered Spaces with Respect to a Spread in PG(n,q) , 2000 .

[13]  R. Trombetti,et al.  Maximum scattered linear sets of pseudoregulus type and the Segre variety $\mathcal{S}_{n,n}$ , 2012, 1211.3604.

[14]  M. Hasse,et al.  W. H. Greub, Multilinear Algebra. (Die Grundlehren der mathematischen Wissenschaften. Band 136). XII + 225 S. Berlin/Heidelberg/New York 1967. Springer-Verlag. Preis geb. DM 32,– , 1971 .