Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4587620 | Journal of Algebra | 2008 | 16 Pages |
Abstract
The present paper deals with algebraic tori and essential dimension in three unrelated contexts. After some preliminaries on essential dimension, versal torsors and tori, we explicitly construct a versal torsor for PGLn, n⩾5 odd, defined over a field of transcendence degree over the base field. This recovers a result of Lorenz, Reichstein, Rowen and Saltman. We also discuss the so-called “tori method” which gives a geometric proof of a result of Ledet on the essential dimension of a cyclic p-group. In the last section we compute the essential dimension of the functor K↦H1(K,GLn(Z)), the latter set being in bijection with the isomorphism classes of n-dimensional K-tori.
Related Topics
Physical Sciences and Engineering
Mathematics
Algebra and Number Theory