Answer to Question #17112 in Abstract Algebra for Tsit Lam
Let R, S be rings such that Mm(R) ∼= Mn(S). Does this imply that m = n and R ∼ S?
The answer is “no”. For instance,for R = M2(Q) and S = M3(Q), we have R is not isomorphic to S (by dimension considerations), but M3(R) ∼= M2(S) since both rings are isomorphic to M6(Q).
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