Torsion sheaf
In mathematics, a torsion sheaf is a sheaf of abelian groups formula_1 on a site for which, for every object "U", the space of sections formula_2 is a torsion abelian group. Similarly, for a prime number "p", we say a sheaf formula_1 is "p"-torsion if every section over any object is killed by a power of "p". A torsion sheaf on an étale site is the union of its constructible subsheaves.