Algebra-Modules generalize Ring-Modules?

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In summary, the conversation discusses the similarities between the notions of an R-module and a representation of R, as well as an A-module and a representation of A. The definition of a representation of a unital ring R and a unital associative algebra A is also provided, highlighting the role of homomorphisms in these structures. The question is raised whether the notion of a representation of a unital associative algebra generalizes the notion of a representation of a unital ring. The expert explains that this is indeed the case, as an algebra is a type of ring and an algebra endomorphism is a type of endomorphism of the underlying ring. This clarification is based on the understanding that the notion of an associative algebra is a general
  • #1
gauss mouse
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Throughout this post, I consider "R-module" and "representation of R" to be the same.
Similarly, I consider "A-module" and "representation of A" to be the same.

I define of a representation of a unital ring R as an Abelian group M together with a homomorphism from R to the unital ring of endomorphisms of M.

I define of a representation of a unital associative algebra A as a vector space V together with a homomorphism from A to the unital associative algebra of endomorphisms of V.

Question:
Is it so that the notion of a representation of a unital associative algebra generalises the notion of a representation of a unital ring? I think I've heard this result, but can't find it by a Google search.

It would seem strange if it were true, since the notion of a unital ring actually generalizes the notion of a unital associative algebra.
 
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  • #2
An algebra is a type of ring and an algebra endomorphism is in particular an endomorphism of the underlying ring. Similarly, a vector space is in particular an abelian group and an endomorphism of a vector space is an endomorphism of the underlying abelian group. So if you start with a rep V of an algebra A, i.e. with a map A->EndV, then you can forget the algebra structure on A and the vector space structure on V, i.e. you can view A as just a ring and V as just an abelian group, and everything will still work out. The map A->EndV is still a homomorphism of rings; the only new thing here is that we're taking End in the category of abelian groups.

Does this clarify things for you? Apologies if I misunderstood what you were asking.
 
  • #3
morphism said:
An algebra is a type of ring and an algebra endomorphism is in particular an endomorphism of the underlying ring. Similarly, a vector space is in particular an abelian group and an endomorphism of a vector space is an endomorphism of the underlying abelian group. So if you start with a rep V of an algebra A, i.e. with a map A->EndV, then you can forget the algebra structure on A and the vector space structure on V, i.e. you can view A as just a ring and V as just an abelian group, and everything will still work out. The map A->EndV is still a homomorphism of rings; the only new thing here is that we're taking End in the category of abelian groups.

Does this clarify things for you? Apologies if I misunderstood what you were asking.

Thank you. What you say seems to confirm my intuition and suggests that perhaps I was wrong. What I thought I had heard somewhere was that a representation of a group is a special case of a representation of an algebra.

I think I may have found the key to the problem. It says here under "Associative Algebras", that the notion of an associative algebra is a generalization of the notion of a ring. Maybe that's the key here.
 
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1. What are Algebra-Modules and Ring-Modules?

Algebra-Modules and Ring-Modules are mathematical structures that are used to generalize the concepts of algebra and ring theory, respectively. Algebra-Modules are modules over an algebra, while Ring-Modules are modules over a ring. Both are sets with operations defined on them that satisfy certain properties.

2. How do Algebra-Modules generalize Ring-Modules?

Algebra-Modules generalize Ring-Modules by allowing the underlying ring to be replaced by a more general algebra. This means that the operations and properties of the underlying algebra are also applicable to the module, making it a more versatile mathematical structure.

3. What are the benefits of generalizing Ring-Modules to Algebra-Modules?

There are several benefits to generalizing Ring-Modules to Algebra-Modules. These include a wider range of applications, more flexibility in terms of structure and operations, and the ability to study and understand more complex mathematical systems.

4. How are Algebra-Modules and Ring-Modules used in mathematics?

Algebra-Modules and Ring-Modules are used in various areas of mathematics such as abstract algebra, commutative algebra, and representation theory. They are also important in applications such as coding theory, cryptography, and quantum mechanics.

5. Are there any real-world applications of Algebra-Modules generalizing Ring-Modules?

Yes, there are many real-world applications of Algebra-Modules generalizing Ring-Modules. Some examples include studying the symmetries in crystal structures, analyzing the behavior of particles in quantum mechanics, and designing error-correcting codes for data transmission.

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