In his paper, Rings with
injective cyclic modules, translated in Soviet Mathematics 4 (1963), p. 36–39, L. A.
Skornjakov states the following lemma: If a cyclic R-module M and all its cyclic
submodules are injective, then the partially ordered set of cyclic submodules of M is
a complete, complemented lattice.
An example is constructed to show that this lemma is false, thus invalidating
Skorniakov’s proof of the theorem: Let R be a ring all of whose cyclic modules are
injective. Then R is semi-simple Artin. The theorem, however, is true. (See Osofsky
[4].)
|