#R^n gives birth to GL(R, n). Does this mean that GL(R,n) can give birth to GL(GL(R,n),n)?

35 messages · Page 1 of 1 (latest)

languid nymph
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I mean from every vector space you can create the set of all its linear non-singular endomorphism (GL(R,n) in our case) and since GL(R,n) itself is a vector space does this mean tha we can create an infinte chain of vector spaces created from the previous one?

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languid nymph
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And if yes, is it ever possible for such a chain to ever stop eventually? ( i.e. V ~ GL(V,n) in some way or idk)

slate imp
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GL_n(R) isn't a vector space

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@languid nymph

languid nymph
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wha

slate imp
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did I accidentally speak spanish?

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GL(V) is the group of invertible linear maps, implicitly V is a vector space

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GL_n(R) isnt a vector space

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so its general linear group isnt a thing

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Like you just read the definitions and see it's nonsense

languid nymph
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My bad, GL(R,n) is a vector space with + being matrix multiplication and * being matrix multiplication with a scalar

slate imp
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no it isnt

languid nymph
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It isnt?

slate imp
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matrix multiplication is commutative?

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that's news to me

languid nymph
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Glaring problem?

slate imp
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I was thinking of rings

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but like... yeah, clearly that wont give a vector space structure

languid nymph
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Ok new idea

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We restrict GL to a subspace such that the matrices commute with each other

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It can't be that much smaller than GL, can it?

slate imp
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You trivially get the copy of R^x at the bare minimum

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actually no, cause your scaling will always force 0 to be in the set

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so * can never have an image contained in GL

languid nymph
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sad

slate imp
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not really

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should've been an immediate realization blobshrug

hardy fractal
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It's a module over the ring of Gl_n(R) not exactly a trivial question

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Replacing A with GL_2(A) for example is a cute way to proof a bunch of intresting things about Gl_n(A) for a ring A using whiteheads lemma

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What you seem to be eventually reaching is called Gl(A) the infinite general linear group for a ring A it's not constructed exactly how you've written it but I'm assuming that's vaguely what you were thinking of

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Gl(A) arises as a direct limit but you can talk about it purely in linear algebraic terms too just Google "infinite general linear groups"

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Also yes Gl_n(Gln(R)) is well defined it's just a module not a vector space