The Stacks project

Small fix

Thanks to  Elías Guisado
https://stacks.math.columbia.edu/tag/05BZ#comment-9034

LaTeX: \Spec

	Introduced the macro

	\def\Spec{\mathop{\rm Spec}}

	and changed all the occurences of \text{Spec} into \Spec.

Explain purity

	We added the following fun lemma: Suppose R ---> S is a ring map
	with R local and M an R-module. Assume that
		S/m_RS is Noetherian
		M/m_RM is finite over S/m_RS
		M is projective as an R-module
	Then any prime q of S which is an associated prime of M \otimes
	k(p) where p = q \cap R is contained in a prime of S lying over
	m_R. This lemma in some sense explains the notion of purity
	introduced in Raynaud-Gruson...

Tags: Added new tags

Assasins and ring maps

	Various lemmas on associated primes and change of rings.