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Hey everyone! Metaphor team here.

We launched Metaphor earlier this morning! It's a search engine based on the same sorts of generative modeling ideas behind Stable Diffusion, GPT-3, etc. It's trained to predict the next link (similar to how GPT-3 predicts the next word).

After GPT-3 came out we started thinking about how pretraining (for large language models) and indexing (for search engines) feel pretty similar. In both you have some code that's looking at all the text on the internet and trying to compress it into a better representation. GPT-3 itself isn't a search engine, but it got us thinking, what would it look like to have something GPT-3-shaped, but able to search the web?

This new self-supervised objective, next link prediction, is what we came up with. (It's got to be self-supervised so that you have basically infinite training data – that's what makes generative models so good.) Then it took us about 8 months of iterating on model architectures to get something that works well.

And now you all can play with it! Very excited to see what sorts of interesting prompts you can come up with.




but aren't the generated results usually fuzzy? how can it produce an exact link that actually exists?


Yeah exactly. That's why you can't really do it with a language model like GPT-3, you have to bake into the architecture the concept of a "link" as a first-class object.


"how can it produce an exact link that actually exists?"

Instead of generating links from scratch it might just be choosing from a pool of already existing links.


This is interesting! I wonder how different the results are from just indexing the contents of the page and semantically searching them (vs. trying to predict the next link). Have you tried anything like that?


That would help retrieve documents based on their contents. But you couldn’t query by a description of what kind of link it is.

So metaphor is able to translate the language of comments (“here are some thoughtful, technical blog posts about AI”) to the language of documents.

Disclaimer: I also work on a semantic search engine.




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