Let $A$ be a finite dimensional $k$-algebra standardly stratified for a partial order $\leqslant$ and $\Delta$ be the direct sum of all standard modules. In this paper we study the extension algebra $E= \text{ Ext}_A^{ \ast} (\Delta, \Delta)$ of standard modules, characterize the stratification property of $E$ for $\leqslant$ and $\leqslant ^{ op}$, and obtain a sufficient condition for $E$ to be a generalized Koszul algebra (in a sense which we define).
Categories: math.RT math.RA