Brent Yorgey

Associate professor of CS at Hendrix College in Conway, AR. Open-source Haskell development, education, competitive programming, type theory, category theory, combinatorics, etc.

Homepage: http://ozark.hendrix.edu/~yorgey/
Blog: https://byorgey.github.io/blog/

Last Notes

2026-05-07 14:19:34 UTC

My department is hiring a 1-year visitor in mathematics. Please pass along to anyone you know who might be interested - this is a really fantastic place to work, with engaged students, supportive colleagues, and no one forcing you to use LLMs for anything.
https://hcm.paycor.com/l/r/D555BCF0

2025-09-19 10:13:39 UTC

Happy 8th birthday! Best birthday present ever! @npub1hnv…5hr9
https://media.mathstodon.xyz/media_attachments/files/115/230/418/353/270/847/original/ac84579c90bd994a.jpg

2025-06-16 20:41:33 UTC

New blog post, "Monads are not like burritos", in which I reflect on the history of a meme and continue the process of turning into a cranky old-timer
https://byorgey.github.io/blog/posts/2025/06/16/monads-are-not-burritos.html

2025-03-20 21:07:34 UTC

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I showed this post to my 7yo and he is super excited! (So am I, to be honest!)

2024-12-21 22:46:59 UTC

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Or maybe you could interpret "slaughtered in 3 days" as less than or equal to 3 days, as in, "these had all better be slaughtered 3 days from now". So the lazy servants slaughter one pig the first day, then on the second day they realize their problem and slaughter the remaining 299.

2024-12-14 22:10:28 UTC

I found 7yo drawing on a sheet of paper. He had drawn 8 dots in a circle and was drawing lines between all possible pairs of dots. I told him it was called \(K_8\) (and showed him how to write the 8 as a subscript). He thought that was cool and labelled his drawing. I then asked him to draw \(K_3, K_2, K_1\), and \(K_0\). He did not even hesitate at \(K_0\) but gleefully wrote \(K_0\) labelling a blank part of the paper.
He then wanted to draw \(K_{10}\) but I told him it would take too long (we had to leave shortly). I tried to explain something about how the number of lines grew quadratically, though not in those words of course. "Oh yeah," he said, "like how \(K_8\) has eight times seven lines." He double counted them, of course, but I was impressed he thought of a way to count them at all.
Looks like we have another budding mathematician on our hands! #math #kids

2024-11-06 19:13:53 UTC

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I would think the terms of any "reasonable syntax" could be encoded as natural numbers (via Gödel numbering, or writing down a text encoding and reading off the bits, etc.). Given this purported "reasonable syntax", then, we could define the forbidden f(i,n) by first trying to decode i as a term of the syntax; if it does not decode, return, say, 0, and if it does, interpret the resulting term as a function ℕ→ℕ and output the result of that function on n.

2024-09-28 21:29:43 UTC

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The values of \(n\) in your list seem to be off by one?

2024-09-10 18:52:50 UTC

At #icfp2024 Zubin Duggal (https://well-typed.com/people/zubin/) showed me this picture from a new Operations Control Center for part of Delhi's Metro system. Apparently the system status display on the giant screens is rendered with the Haskell diagrams EDSL!
https://media.mathstodon.xyz/media_attachments/files/113/114/738/657/159/846/original/33adf0a78b9dd0be.jpg