Projective model structure on nonnegative chain complexes
= Projective model structure on nonnegative chain complexes
{title2=$\mathbf{Ch}_{\geq0}(R)$}
The <model category> of nonnegative complexes of left modules has <quasi-isomorphisms> as <model weak equivalences>, positive-degree surjections as <model fibrations>, and degreewise injections with projective cokernel as <model cofibrations>. All objects are fibrant; cofibrant objects are degreewise projective.