Torsion sheaf

In mathematics, a torsion sheaf is a sheaf ${\mathcal {F}}$ on a site for which, for every quasi-compact U, the space of sections $\Gamma (U,{\mathcal {F}})$ is a torsion group. Similarly, for a prime number l, we say a sheaf ${\mathcal {F}}$ is l-torsion if every section over any quasi-compact is killed by a power of l.

A torsion sheaf on an étale site is the union of its constructible subsheaves.

See also

• Twisted sheaf

References

• J. S. Milne (2012). "Lectures on Étale Cohomology
• J. S. Milne, Étale Cohomology