Great post, but what struck me (again, like every time I look at cos similiarity) is how unreasonably well it works. It's just one of those things that's so "weird" about our world: why would cosine similarity work in n-dimensional semantic spaces? It's so stupid simple, and it intuitively makes sense, and it works really well. Crazy cool.
I'm reminded of that old Eugene Wigner quote: "The most incomprehensible thing about the universe is that it is comprehensible."
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