Let $x$ be a nonzerodivisor on a local Noetherian ring $(R,m).$ Let $M,N$ be finitely generated $R/xR$-modules.

**How to show the existence of the following exact sequence**

$\cdots\longrightarrow Ext_{R/xR}^{n}(M,N)\longrightarrow Ext_{R}^{n}(M,N)\longrightarrow Ext_{R/xR}^{n-1}(M,N)\longrightarrow \cdots.$

Any reference will be useful.

Algèbre commutativeX (unfortunately not yet translated into English, as far as I know). $\endgroup$ – abx Jan 2 at 16:46