# Does this statement about Hilbert spaces make any sense?

I have found this tweet about git and don't know what to make of it.

I think it's written as a joke, but it could have been written in Chinese, and I'd understand about just as much.

Does this make any sense mathematically?

Or is it just as nonsensical as most "computer-speak" on most TV shows?

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+1 for the GUI interface in Visual Basic –  Lightness Races in Orbit Feb 13 at 14:09
I prefer the AFIS fingerprint GUI client that wastes huge amounts of database and network to display loads of useless non-matches. –  Martin James Feb 13 at 14:12
@MartinJames: To be fair, even in reality you can somewhat imagine upper management saying "no no no, the user needs to see that progress is being made in the search!" –  Lightness Races in Orbit Feb 13 at 14:13
@LightnessRacesinOrbit - waiting for some lawyer to pop up and claim 'the AFIS system plainly is not effective because it displays non-matches - it doesn't know what it's doing! I move to dismiss all the fingerprint evidence from the axes and chainsaw'. –  Martin James Feb 13 at 14:20

This is an old joke that's done the rounds on the internet a few times.

Stephan Rauh gave it a pretty good treatment on his blog last year, in which he concludes that it is indeed nonsense:

Funny thing is it took me a while to figure out that the sentence really is utter nonsense. Most people immediately dismiss it as a joke – but they’ll never know for sure. It sounds oh so scientific. Mathematicians like me know what the words mean, and we know a lot of weird ways to make sense of them. So my first reaction was “It’s obviously a joke – but what’s the truth behind it?”.

Well, there’s none. Or rather, there is. You can make the branch operator a homeomorphic endofunctor living in a Hilbert space by defining a mapping from the set of all git repositories to the sequence space ℓ∞. You can achieve this easily by using the byte representations of the git repository.

You can do even simpler by interpreting the bytes a git repository consists of as a giant number. Thus every each git repository is an integer, i.e. an element of Z, which can easily embedded into a Hilbert space. Unfortunately the operations of the Hilbert space don’t map to a sensible operations on git repositories.

But still, it sounds intriguing. This much is true: the branch function is a surjective function mapping a git repository to another. Let’s use the commit operation as the addition. Obviously, the set of git repositories form an abelian group, but the branch operator isn’t a homomorphism. Actually, that’s good news, because it would be useless otherwise.

I had a lot of fun this afternoon to find out that almost every word of the sentence is nonsense:

• branch() isn’t a functor but a function,
• it’s not homomorphic, let alone homeophic,
• it’s hard to see how the Hilbert space is defined and so on.
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This is awesome. Thanks for the link :) –  Cristi Diaconescu Feb 13 at 14:13