Kaplansky's theorem on projective modules
= Kaplansky's theorem on projective modules
{wiki=Kaplansky's_theorem_on_projective_modules}
Kaplansky's theorem on projective modules, formulated by David Kaplansky, provides a significant result in the theory of modules over rings. The theorem states that any projective module over a ring is a direct summand of a free module if and only if the ring is a certain type of ring known as a "Baer ring.