[Merged by Bors] - chore(LinearAlgebra/TensorProduct): fix duplication

[yuma-mizuno]

This was unintentionally made in #16776 by myself.

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[github-actions]

PR summary aa40cbc5b6

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

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[mo271]

Do we do deprecation alias for those?

[yuma-mizuno]

Do we do deprecation alias for those?

I have added.

[eric-wieser]

bors d+

If you wanted, you could deprecate the *fold names in favor of subscripts (the reverse of what you've done here) if you'd find them easier to discover. Of course, by ext x y z works fine anyway, so no one should really need these lemmas...

[mathlib-bors]

✌️ yuma-mizuno can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[yuma-mizuno]

Of course, by ext x y z works fine anyway, so no one should really need these lemmas...

In my understanding, ext x y z only works in the local ext setting in this file. I'm not sure why the setting is like this.

[yuma-mizuno]

The subscript name was an unintentional product, but it might not be a bad name.

[yuma-mizuno]

bors r+

[eric-wieser]

Of course, by ext x y z works fine anyway, so no one should really need these lemmas...

In my understanding, ext x y z only works in the local ext setting in this file.

Yes this is true,

I'm not sure why the setting is like this.

This was a decision made near the end of mathlib3, for performance. We could try revisiting it now that we have better lean 4 and benchmarking infrastructure.

[yuma-mizuno]

bors r+

[mathlib-bors]

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