A. A'Campo-Neuen and J. Hausen gave an example of an algebraic torus action on an open subset of the affine four space that admits no quotient in the category of algebraic varieties. We show that this example admits a quotient in the category of dense constructible subsets and thereby answer a question of A. Białynicki-Birula.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm116-2-1,
author = {Devrim Celik},
title = {A categorical quotient in the category of dense constructible subsets},
journal = {Colloquium Mathematicae},
volume = {116},
year = {2009},
pages = {147-151},
zbl = {1173.14035},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm116-2-1}
}
Devrim Celik. A categorical quotient in the category of dense constructible subsets. Colloquium Mathematicae, Tome 116 (2009) pp. 147-151. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm116-2-1/