Solution

ID: past-exam-of-the-algebra-course-of-the-university-of-oxford/2007/a/1/3/solution

Coordinatewise multiplication gives , so the third module is cyclic.
A submodule of a cyclic module need not be cyclic. In the second example the first-row space is a left ideal and hence a submodule of the regular module . The regular module is cyclic, generated by , whereas its first-row submodule has just been shown not to be cyclic. Thus the proposed inheritance property fails even for a finite-dimensional algebra.

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