Nostr notes by Brent Yorgey

The word "sprinkle" comes from the Rev. John Sprinkle, a ...

2026-10-16T00:24:13Z

The word "sprinkle" comes from the Rev. John Sprinkle, a Presbyterian minister who in 1843 invented a new way of baptizing people by putting water directly on their head. #lowqualityfact

OH 5yo singing this morning: Where the north wind / Meets the sea ...

2026-10-09T14:04:56Z

OH 5yo singing this morning:

Where the north wind / Meets the sea
There's a river / full of broccoli

it clearly ought to be called Schadenschauen. No idea if this is ...

2026-09-25T10:21:36Z

In reply to nevent1q…kz02
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it clearly ought to be called Schadenschauen. No idea if this is a real German word.

Happy birthday to my favorite 9-year-old! @npub1hnv…5hr9 ...

2026-09-22T01:52:16Z

Happy birthday to my favorite 9-year-old!

Li Chen (npub1hnv…5hr9)

Just realized that the Royal Mail delivers the post, whereas the ...

2026-08-17T20:29:47Z

Just realized that the Royal Mail delivers the post, whereas the US Postal Service delivers the mail. What the heck, English.

My 14yo son would like to learn how to read academic papers, so I ...

2026-08-15T22:00:14Z

My 14yo son would like to learn how to read academic papers, so I offered to read one together with him. He wants to start with a paper about Rust (for context, he has written tens of thousands of lines of Rust, from a raytracer to a library for constructing custom Minecraft servers). I don't know any Rust, but of course I know a good deal of PL theory and how to read research papers; I think we will make a good team. Any suggestions of good papers for us to read?

Yes, I think so.

2026-06-25T16:11:44Z

In reply to nevent1q…ku8v
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Yes, I think so.

Did you see my example from elsewhere in the thread of multisets ...

2026-06-25T15:52:00Z

In reply to nevent1q…u8x7
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Did you see my example from elsewhere in the thread of multisets that allow infinite multiplicity? In that case the star of a multiset is the multiset with the same elements, with each having infinite multiplicity, NOT the multiset with infinite copies of everything.

Suppose we have a monoid M with a "star" operation * : M ...

2026-06-24T22:28:50Z

Suppose we have a monoid M with a "star" operation * : M -> M satisfying a* = aa*. I'm not sure if there are other laws we might also want (e.g. perhaps we also want a* = a*a), but the idea is that a* is supposed to represent "combining a with itself infinitely often", i.e. the limit \(\lim_{n \to \infty} a^n\). One simple example would be the natural numbers adjoined with positive infinity under addition, where 0* = 0 and n* = infinity for every n > 0. Another example is the booleans under conjunction or disjunction, where false* = false and true* = true. The booleans under xor, on the other hand, do not have a star operation.

Does this have a name? I found the concept of a "complete monoid", but that seems stronger than what I want: a complete monoid allows making sense of arbitrary infinitary products, but I only want to be able to take infinite powers (though off the top of my head I can't think of an example monoid that has a star but is not complete...)

My department is hiring a 1-year visitor in mathematics. Please ...

2026-05-07T14:19:34Z

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

Happy 8th birthday! Best birthday present ever! @npub1hnv…5hr9 ...

2025-09-19T10:13:39Z

Happy 8th birthday! Best birthday present ever! Li Chen (npub1hnv…5hr9)

New blog post, "Monads are not like burritos", in which I ...

2025-06-16T20:41:33Z

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

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

2025-03-20T21:07:34Z

In reply to nevent1q…httq
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I showed this post to my 7yo and he is super excited! (So am I, to be honest!)

Or maybe you could interpret "slaughtered in 3 days" as ...

2024-12-21T22:46:59Z

In reply to nevent1q…d57m
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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.

I found 7yo drawing on a sheet of paper. He had drawn 8 dots in a ...

2024-12-14T22:10:28Z

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

I would think the terms of any "reasonable syntax" could ...

2024-11-06T19:13:53Z

In reply to nevent1q…9xg8
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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.

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

2024-09-28T21:29:43Z

In reply to nevent1q…5u3c
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The values of \(n\) in your list seem to be off by one?

At #icfp2024 Zubin Duggal (https://well-typed.com/people/zubin/) ...

2024-09-10T18:52:50Z

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!