Cyclic module
In mathematics, more specifically in ring theory, a cyclic module or monogenous module is a module over a ring that is generated by one element.  The concept is analogous to cyclic group, that is, a group that is generated by one element.

Definition 

A left R-module M is called cyclic if M can be generated by a single element i.e.  for some x in M. Similarly, a right R-module N is cyclic if  for some .

Examples 

 (2) as a Z-module is a cyclic module.
 In general, any Z-module is a cyclic module.
 In fact, every cyclic group is a cyclic Z-module.
 Every simple R-module M is a cyclic module since the submodule generated by any non-zero element x of M is necessarily the whole module M. In general, a module is simple if and only if it is nonzero and is generated by each of its nonzero elements.
 If the ring R is considered as a left module over itself, then its cyclic submodules are exactly its left principal ideals as a ring. The same holds for R as a right R-module, mutatis mutandis.
 If R is F[x], the ring of polynomials over a field F, and V is an R-module which is also a finite-dimensional vector space over F, then the Jordan blocks of x acting on V are cyclic submodules.  (The Jordan blocks are all isomorphic to ; there may also be other cyclic submodules with different annihilators; see below.)

Properties 

 Given a cyclic R-module M that is generated by x, there exists a canonical isomorphism between M and , where  denotes the annihilator of x in R.

Every module is a sum of cyclic submodules.