I have started reading the book "The Geometry of moduliModuli Spaces of sheaves"Sheaves" by Huybrechts and Lehn. This is a statement in this book at page no.3page no.3 the last line.
"$E$ is pure if and only if all associated points of $E$ have the same dimension." Definition for associated points of a sheaf is as follows:
$Ass(E)=\{x∈X|m_x∈AssE_x\}$.
- How to prove this statement specially the converse part that if all associated points have the same dimension, then $E$ is pure?
- Can anyone suggest me some reference in this regard?