Abstract
In this note, we consider unramified cohomology with \({{\mathbb {Z}}}/2\) coefficients for some (degree two) quotient varieties and describe a method that allows one to prove the non-vanishing of these groups under certain conditions. We apply this method to prove a non-vanishing statement in the case of Kummer varieties. Combining this with work of Colliot-Thélène and Voisin, we obtain a new type of three-dimensional counterexample to the integral Hodge conjecture.
We’re sorry, something doesn't seem to be working properly.
Please try refreshing the page. If that doesn't work, please contact support so we can address the problem.
References
Auel, A., Colliot-Thélène, J.-L., Parimala, R.: Universal Unramified Cohomology of Cubic Fourfolds Containing a Plane. Brauer Groups and Obstruction Problems, Volume 320 of Progr. Math, pp. 29–55. Birkhäuser, Cham (2017)
Atiyah, M.F., Hirzebruch, F.: Analytic cycles on complex manifolds. Topology 1, 25–45 (1962)
Beauville, A.: Sur l’anneau de Chow d’une variété abélienne. Math. Ann. 273, 647–652 (1985)
Benoist, O., Ottem, J.C.: Failure of the integral Hodge conjecture for threefolds of Kodaira dimension zero. Comment. Math. Helv. (to appear)
Bloch, S., Esnault, H.: The coniveau filtration and non-divisibility for alge braic cycles. Math. Ann. 304, 303–314 (1996)
Bloch, S., Kato, K.: \(p\)-adic étale cohomology. Publ. Math. de l’IHÉS 63, 107–152 (1986)
Bloch, S., Ogus, A.: Gersten’s conjecture and the homology of schemes. Ann. sci. de l’É.N.S. 4e série. 7(2), 181–201 (1974)
Bloch, S., Srinivas, V.: Remarks on correspondences and algebraic cycles. Am. J. Math. 105(5), 1235–1253 (1983)
Bott, R., Tu, L.W.: Differential Forms in Algebraic Topology. Springer, Berlin (1982)
Colliot-Thélène, J.-L.: Cohomologie non ramifiée dans le produit avec une courbe elliptique. Manuscripta Mathematica 160(3–4), 561–565 (2019)
Colliot-Thélène, J.-L., Ojanguren, M.: Variétés unirationnelles non rationnelles: au-delà de l’exemple d’Artin et Mumford. Invent. math. 97(1), 141–158 (1989)
Colliot-Thélène, J.-L., Voisin, C.: Cohomologie non ramifiée et conjecture de Hodge entiére. Duke Math. J. 161(5), 735–801 (2012)
Gabber, O.: appendix to Exposant et indice d’algèbres simples centrales non ramifiées, by J.-L. Colliot-Thélène. Enseign. Math. 48(1)-(2), 127–146 (2002)
Grabowski, C.: On the integral Hodge conjecture for \(3\)-folds. Ph.D. Thesis, Duke University (2004)
Knus, M.A., Parimala, R., Srinivas, V.: Azumaya algebras with involutions. J. Algebra 130, 65–82 (1990)
Kollár, J.: Classification of irregular varieties. In: Ballico, E., Catanese, F., Ciliberto, C., (eds.) Lecture Notes in Math vol. 1515, Springer (1990)
Shen, M.: Vanishing cycles under base change and the integral Hodge conjecture. arxiv:1901.07091
Skorobogatov, A.: Cohomology and the Brauer group of double covers. In: Auel A., Hassett B., Vàrilly-Alvarado A., Viray B., Brauer Groups and Obstruction Problems. Progress in Mathematics, vol. 320. Birkhäuser (2017)
Spanier, E.: The homology of Kummer manifolds. Proc. AMS 7(1), 155–160 (1956)
Totaro, B.: On the integral Hodge and Tate conjectures over a number field. Forum Math. Sigma 1, e4 (2013). (13 pages)
Totaro, B.: The integral Hodge conjecture for 3-folds of Kodaira dimension zero. arXiv:1907.08670
Voisin, C.: On integral Hodge classes on uniruled or Calabi-Yau threefolds. In: Moduli Spaces and Arithmetic Geometry, Adv. Stud. Pure Math. vol. 45, pp. 43–73. Mathematical Society of Japan, Tokyo (2006)
Acknowledgements
The author would like to thank Olivier Benoist for his feedback and for finding a mistake in a previous draft (that led to this draft). He would also like to thank John Christian Ottem for his interest. Finally, many thanks to the excellent referee for carefully reading this paper and providing many useful comments.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Diaz, H. On the unramified cohomology of certain quotient varieties. Math. Z. 296, 261–273 (2020). https://doi.org/10.1007/s00209-019-02432-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00209-019-02432-4