Thinnings: Sublist Witnesses and de Bruijn Index Shift Clumping

There was a thread on mastodon recently where Conor Mcbride was discussing some really cool stuff. I think the intent was to get at something more interesting, but this is the first place I’ve seen thinnings explained in a way without too many complex trappings around and it really clicked with me. I think I had a primed mind to see something useful to my current set of problems and solutions there. It unlocked a torrent of ideas related to lambda egraphs and generalized unions finds that I’m quite excited to talk about in the next couple posts.