Direct-sum decompositions of modules with semilocal endomorphism rings
نویسندگان
چکیده
Let R be a ring and C a class of right R-modules closed under finite direct sums. If we suppose that C has a set of representatives, that is, a set V(C) ⊆ C such that every M ∈ C is isomorphic to a unique element [M ] ∈ V(C), then we can view V(C) as a monoid, with the monoid operation [M1] + [M2] = [M1 ⊕M2]. Recent developments in the theory of commutative monoids (e.g., [4], [15]) suggest that one might obtain useful insights on decompositions of modules by considering the monoids V(C).
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