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Stream: learning: questions

Topic: Vector spaces versus dependent types


view this post on Zulip David Corfield (Apr 01 2025 at 07:18):

I've been interested for a while in the contrast between the vector-space approach to semantics, used by LLMs, and [[type-theoretic approaches]]. Where one may exploit the capacity of a high-dimensional vector space to contain very many near orthogonal vectors to keep different meaning concepts apart, the type-theoretic way looks to constrict via the typing discipline. Dependent type theories allow towers of types, each depending on the one (and hence ones) below.

I was interested to see in this paper the appearance of a hierarchical structure within a vector space associated to an LLM:

image.png

Now, could there be a way to mediate between the two approaches, such as a way to generate towers of dependent types from a collection of vectors in a vector space?

You might think that [[linear dependent type theory]] could play a role in mediating between the two extremes, allowing towers of different heights topped off by vector spaces (if linear types are restricted to depend only on nonlinear ones).

Now, is there anything useful to say mathematically about this situation? Seems like approaches to phylogenetic tree formation should be near.

It's surely easier to pass from a tower of sets to a corresponding vector space than to reconstruct a tower in reverse, or rather that there would be significant choices to be made to optimize in some sense this latter process.

Ring any bells?