Serial module
In abstract algebra, a uniserial module M is a module over a ring R, whose submodules are totally ordered by inclusion. This means simply that for any two submodules N1 and N2 of M, either N 1 ⊆ N 2 {\displaystyle N_{1}\subseteq N_{2}} or N 2 ⊆ N 1 {\displaystyle N_{2}\subseteq N_{1}} .