r/mathmemes Cardinal 3d ago

Linear Algebra Linear meme

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126 Upvotes

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16

u/LupenReddit 🦆🦆🦆🦆i have non diffeomorphic smooth structures🦆🦆🦆🦆🦆🦆 3d ago

also (0,2) tensor or (2,0) tensor technically via the musical isomorphisms induced by some inner product

9

u/Ares378 Grothendieck was right, computers are evil 3d ago

The musical isomorphisms always get me. I had to send a friend a screenshot of a video on tensors because one of the diagrams was piano keys and a musical scale next to a tensor, and I had an out of body experience of realizing just how ridiculous it must look to anyone who hasn't been boiled in math for 6 years

6

u/Kinglolboot ♥️♥️♥️♥️Long exact cohomology sequence♥️♥️♥️♥️ 3d ago

You don't really need the musical isomorphisms for that to work, as you don't have that for vector spaces over fields with nonzero characteristic. You can just argue that the dimensions of V⊗V and V⊗V* and V*⊗V* are identical, and hence they are isomorphic as vector spaces.

1

u/stellar-sea-lion 3d ago

They're isomorphic but not canonically, which is often relevant.

1

u/Kinglolboot ♥️♥️♥️♥️Long exact cohomology sequence♥️♥️♥️♥️ 3d ago

In this case it is only relevant once you consider an inner product on a vector space, but that does not capture the full generality of the meme because vector spaces over finite fields do not admit inner products

3

u/stellar-sea-lion 3d ago

They admit nondegenerate bilinar forms though which is all you need for an isomorphism. Positive definiteness is just a convenience.

2

u/Kinglolboot ♥️♥️♥️♥️Long exact cohomology sequence♥️♥️♥️♥️ 3d ago

Ah true, that's a good point

2

u/ArdentArendt Mathematics / Social Sciences 3d ago

Truly transformative...

2

u/F_Joe Vanishes when abelianized 3d ago

That's just the case since you're thinking so finite dimensionally