  Let $\mathcal{A}$ be an abelian category, or more generally a weakly
idempotent complete exact category, and suppose we have two complete hereditary
cotorsion pairs $(\mathcal{Q}, \widetilde{\mathcal{R}})$ and
$(\widetilde{\mathcal{Q}}, \mathcal{R})$ in $\mathcal{A}$ satisfying
$\widetilde{\mathcal{R}} \subseteq \mathcal{R}$ and $\mathcal{Q} \cap
\widetilde{\mathcal{R}} = \widetilde{\mathcal{Q}} \cap \mathcal{R}$. We show
how to construct a (necessarily unique) abelian model structure on
$\mathcal{A}$ with $\mathcal{Q}$ (respectively $\widetilde{\mathcal{Q}}$) as
the class of cofibrant (resp. trivially cofibrant) objects and $\mathcal{R}$
(respectively $\widetilde{\mathcal{R}}$) as the class of fibrant (resp.
trivially fibrant) objects.
