ideals of a matrix ring
asked 2016-12-09 11:09:51 -0500
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gives all the $n\times m$ matrices over R with a module structure. To construct ideals of matrix rings, I would need something like
where $I$ is an ideal of $R$. But the above command would not work as $I$ is not a ring. Any suggestions what to do? Or more generally, how to construct the set of all matrices with entries from a given set?