# nLab Ziegler spectrum

Let $k$ be a fixed field. Consider associative $k$-algebra $A$ and its category of right modules $Mod_A$.

Recall that a monomorphism $f:M\to N$ in $Mod_A$-modules is pure if after tensoring with any left $A$-module $L$ gives a mono $M\otimes_A L\stackrel{f\otimes L}\to N\otimes_A L$. A module $M$ in $Mod_A$ is pure-injective if every pure mono $M\to N$ splits. This is clearly a weaker property than being an injective object.

Given an associative algebra $A$, its Ziegler spectrum $Zsp(A)$ is the topological space whose points are the isomorphism classes $[M]$ of indecomposable pure-injective $A$-modules $M$ and the topology is defined in terms of pp-formulas (or finite matrices) over $A$. Here pp stands for “positive primitive in the usual language for $A$-modules”

The importance of Ziegler spectrum is in the

Ziegler’s theorem. There is a correspondence between the definable classes in $Mod_A$ and closed subsets of $Zsp(A)$.

There are applications to the spectra of theories of modules.

• Martin Ziegler, Model theory of modules, Ann. Pure Appl. Logic 26 (1984), no. 2, 149–213, MR86c:03034 doi
• Krause pdf
• Grigory Garkusha, Mike Prest (2005) Triangulated categories and the Ziegler spectrum, Algebras and Representation Theory, 8 (4). pp. 499-523, doi, pdf
• Mike Prest, slides
• Mike Prest, Topological and Geometric aspects of the Ziegler Spectrum (1998)
• Lorna Gregory, Thesis, pdf
• Mike Prest, Purity, spectra and localisation, Enc. of Math. and its Appl. 121, Camb. Univ. Press 2009
Revised on May 23, 2012 17:18:34 by Zoran Škoda (193.51.104.33)