{{short description|Algebraic structure}} In mathematics, a (left) '''coherent ring''' is a ring in which every finitely generated left ideal is finitely presented.
Many theorems about finitely generated modules over Noetherian rings can be extended to finitely presented modules over coherent rings.
Every left Noetherian ring is left coherent. The ring of polynomials in an infinite number of variables over a left Noetherian ring is an example of a left coherent ring that is not left Noetherian.
A ring is left coherent if and only if every direct product of flat right modules is flat {{harv|Chase|1960}}, {{harv|Anderson|Fuller|1992|p=229}}. Compare this to: A ring is left Noetherian if and only if every direct sum of injective left modules is injective.
==References== *{{Citation | last1=Anderson | first1=Frank Wylie | last2=Fuller | first2=Kent R | title=Rings and Categories of Modules | publisher=Springer-Verlag | location=Berlin, New York | isbn=978-0-387-97845-1 | year=1992}} *{{Citation | last1=Chase | first1=Stephen U. | title=Direct products of modules | mr=0120260 | year=1960 | journal=Transactions of the American Mathematical Society | volume=97 | pages=457–473 | doi=10.2307/1993382 | issue=3 | publisher=American Mathematical Society | jstor=1993382| doi-access=free }} *{{eom|title=Coherent ring|first=V.E.|last= Govorov}}
Category:Ring theory