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Deep Learning Is Applied Topology

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Re: Deep Learning Is Applied Topology

#2
If it was topology we wouldn't bother to warp the manifold so we can do similarity search. No, it's geometry, with a metric. Just as in real life, we want to be able to compare things.

Topological transformation of the manifold happens during training too. That makes me wonder: how does the topology evolve during training? I imagine it violently changing at first before stabilizing, followed by geometric refinement. Here are some relevant papers:

* Topology and geometry of data manifold in deep learning (https://arxiv.org/abs/2204.08624)

* Topology of Deep Neural Networks (https://jmlr.org/papers/v21/20-345.html)

* Persistent Topological Features in Large Language Models (https://arxiv.org/abs/2410.11042)

* Deep learning as Ricci flow (https://www.nature.com/articles/s41598-024-74045-9)

Re: Deep Learning Is Applied Topology

#3
Data doesn't actually live on a manifold. It's an approximation used for thinking about data. Near total majority, if not 100%, of the useful things done in deep learning have come from not thinking about topology in any way. Deep learning is not applied anything, it's an empirical field advanced mostly by trial and error and, sure, a few intuitions coming from theory (that was not topology).

Re: Deep Learning Is Applied Topology

#4
I’ve always enjoyed this framing of the subject, the idea of mapping anything as hyperplanes existing in a solution space is one of the ideas that really blew my hair back during my academic studies. I would nitpick at your “dots in a circle example - with the stoner reference joke” I could be mistaken, but common practice isn’t to “move to a higher dimension”, but use a kernel (i.e. parameterize the points into the polar |r,theta> basis). All things considered, nice article.

Re: Deep Learning Is Applied Topology

#6
This is also how I've often thought about deep learning -- focusing on the geometry of the data at each layer rather than the weights and biases is far more revealing.

I've always been hopeful that some algebraic topology master would dig into this question and it'd provide some better design principles for neural nets. which activation functions? how much to fan in/out? how many layers?

Re: Deep Learning Is Applied Topology

#8
post #3

Data doesn't actually live on a manifold. It's an approximation used for thinking about data. Near total majority, if not 100%, of the useful things done in deep learning have come from not thinking about topology in any way. Deep learning is not applied anything, it's an empirical field advanced mostly by trial and error and, sure, a few intuitions coming from theory (that was not topology).

I cannot understand this prideful resentment of theory common among self-described practitioners.

Even if existing theory is inadequate, would an operating theory not be beneficial?

Or is the mystique combined with guess&check drudgery job security?

Re: Deep Learning Is Applied Topology

#9
Once I read "This has been enough to get us to AGI.", credibility took a nose dive.

In general it's a nice idea, but the blogpost is very fluffy, especially once it connects it to reasoning, there is serious technical work in this area (i.g. https://arxiv.org/abs/1402.1869) that has expanded this idea and made it more concrete.

Re: Deep Learning Is Applied Topology

#10
post #3

Data doesn't actually live on a manifold. It's an approximation used for thinking about data. Near total majority, if not 100%, of the useful things done in deep learning have come from not thinking about topology in any way. Deep learning is not applied anything, it's an empirical field advanced mostly by trial and error and, sure, a few intuitions coming from theory (that was not topology).

Your comment sits in the nice gradient between not seeing at all the obvious relationships between deep learning and topology and thinking that deep learning is applied topology.

See? Everything lives in the manifold.

Now for a great visualization about the Manifold Hypothesis I cannot recommend more this video: https://www.youtube.com/watch?v=pdNYw6qwuNc

That helps to visualize how the activation functions, bias and weights (linear transformations) serve to stretch the high dimensional space so that data go into extremes and become easy to put in a high dimension, low dimensional object (the manifold) where is trivial to classify or separate.

Gaining an intuition about this process will make some deep learning practices so much easy to understand.

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