Roland Lötscher: Essential dimension and canonical dimension of gerbes banded by groups of multiplicative type

roland.loetscher@mathematik.uni-muenchen.de

Submission: 2013, Sep 24

We prove the formula ed(X)=cdim(X)+ed(A) for any gerbe X banded by an algebraic group A which is the kernel of a homomorphism of algebraic tori Q->S with Q invertible and S split. This result is applied to prove new results on the essential dimension of algebraic groups.

2010 Mathematics Subject Classification: 20G15, 14A20, 11E72

Keywords and Phrases: essential dimension, canonical dimension, algebraic stack, gerbe, group of multiplicative type

Full text: dvi.gz 33 k, dvi 90 k, ps.gz 895 k, pdf.gz 169 k, pdf 203 k.


Server Home Page