  We give a short proof of a result due to Katz and West: Let $R$ be a
Noetherian ring and $I_1,\ldots,I_t$ ideals of $R$. Let $M$ and $N$ be finitely
generated $R$-modules and $N' \subseteq N$ a submodule. For every fixed $i \ge
0$, the sets $\mathrm{Ass}_R\left( \mathrm{Ext}_R^i(M, N/I_1^{n_1}\cdots
I_t^{n_t} N') \right)$ and $\mathrm{Ass}_R\left( \mathrm{Tor}_i^R(M,
N/I_1^{n_1}\cdots I_t^{n_t} N') \right)$ are independent of $(n_1,\ldots,n_t)$
for all sufficiently large $n_1,\ldots,n_t$.
