2026-07-28T17:24:06Z https://njump.me Brent Yorgey https://njump.me/npub1g8ewl5mmc6n26axgaswwppc8ppyxqukqeavdm2yf06s4ha9j0v2sna88a8 https://media.mathstodon.xyz/accounts/avatars/000/003/032/original/1d4cbbda8969f7ab.jpg https://media.mathstodon.xyz/accounts/avatars/000/003/032/original/1d4cbbda8969f7ab.jpg https://njump.me/nevent1qqs808r2kh2ydn558e0z9rj4hx9f59kle75q0z3a7jtra3tdf6acgcqzypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa327l3lm5 In reply to <a href='/nevent1qqszn4n4kle5q74r05rpudzgn5w2gunp6vfd45l2lufmkxqm38lj56s4aku8v'>nevent1q…ku8v</a><br/>_________________________<br/><br/>Yes, I think so. 2026-06-25T16:11:44Z https://njump.me/nevent1qqsftk68hqdn735ym4c4mlce59mgmg9rp3ajc9r6ns9yks2vls3cccczypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa326xeq2s In reply to <a href='/nevent1qqsqfgnm5eg5nealnmjgaanxq4xy46zgrmdjejc7l48ld7xjz3ad9qg6gu8x7'>nevent1q…u8x7</a><br/>_________________________<br/><br/>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. 2026-06-25T15:52:00Z https://njump.me/nevent1qqs24w4m3mzqddhsq3agdpyukqldtxrlnc2w6u3anqyxnxnddd4736czypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa326yvda5 Suppose we have a monoid M with a &#34;star&#34; operation * : M -&gt; M satisfying a* = aa*. I&#39;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 &#34;combining a with itself infinitely often&#34;, 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 &gt; 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.<br/><br/>Does this have a name? I found the concept of a &#34;complete monoid&#34;, 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&#39;t think of an example monoid that has a star but is not complete...) 2026-06-24T22:28:50Z https://njump.me/nevent1qqs8389h7r2gsdwpgqm960xy5xv3tf58ylfv0yrvs0mkukfjr30fr6gzypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32mmk93j 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.<br/><br/><a href="https://hcm.paycor.com/l/r/D555BCF0">https://hcm.paycor.com/l/r/D555BCF0</a> 2026-05-07T14:19:34Z https://njump.me/nevent1qqsd8dsq7a9kz3cqlx783etjwcuyjtg4aal4vtagfdtwp0d32yj2wjczypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32g8wz6z Happy 8th birthday! Best birthday present ever! <span itemprop="mentions" itemscope itemtype="https://schema.org/Person"><a itemprop="url" href="/npub1hnve5rtjzfnur0kdfr5y4dx78pdj47elg86j7s4hmy3thdjlgr4sx35hr9" class="bg-lavender dark:prose:text-neutral-50 dark:text-neutral-50 dark:bg-garnet px-1"><span>Li Chen</span> (<span class="italic">npub1hnv…5hr9</span>)</a></span><br/> <img src="https://media.mathstodon.xyz/media_attachments/files/115/230/418/353/270/847/original/ac84579c90bd994a.jpg"> <br/> 2025-09-19T10:13:39Z https://njump.me/nevent1qqszw3w03ds54m93jfhajayyw2s6s29v7hlh5dgqztny7alkt4a7yqqzypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32uprutv New blog post, &#34;Monads are not like burritos&#34;, in which I reflect on the history of a meme and continue the process of turning into a cranky old-timer<br/><br/><a href="https://byorgey.github.io/blog/posts/2025/06/16/monads-are-not-burritos.html">https://byorgey.github.io/blog/posts/2025/06/16/monads-are-not-burritos.html</a> 2025-06-16T20:41:33Z https://njump.me/nevent1qqs92j5sxze23lcj0eqkpxejvxhrfs2gpjmw8k9pvtwaaf0m9y0kvgszypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32r6lrw2 In reply to <a href='/nevent1qqsv5gmvvynhggy4zg6lyy722jlx6dpwnnydff0qlx4lvcf6h2f0nqgwnhttq'>nevent1q…httq</a><br/>_________________________<br/><br/>I showed this post to my 7yo and he is super excited! (So am I, to be honest!) 2025-03-20T21:07:34Z https://njump.me/nevent1qqs9rtu9h9un4eqcmw2x2tkddcw84tqtrnzcxpnjjcn79kp4cezcn8szypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32v8j4ud In reply to <a href='/nevent1qqs0vp6456jldmxp7yyrgz0pvqk3e8vkesc7c58qsg3mzgnwwxnfcdqnxd57m'>nevent1q…d57m</a><br/>_________________________<br/><br/>Or maybe you could interpret &#34;slaughtered in 3 days&#34; as less than or equal to 3 days, as in, &#34;these had all better be slaughtered 3 days from now&#34;. So the lazy servants slaughter one pig the first day, then on the second day they realize their problem and slaughter the remaining 299. 2024-12-21T22:46:59Z https://njump.me/nevent1qqsvsc9dksp643x3kgr75x7tu5vcnj9nuu3ctz3zg38rt3rg3q74r8szypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32p7a4wn 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.<br/><br/>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. &#34;Oh yeah,&#34; he said, &#34;like how \(K_8\) has eight times seven lines.&#34; He double counted them, of course, but I was impressed he thought of a way to count them at all.<br/><br/>Looks like we have another budding mathematician on our hands! #math #kids 2024-12-14T22:10:28Z https://njump.me/nevent1qqs80gq6069ha2uxjruzf7ene0hvtnl3hyqah48j2fvcfyxygdn77tszypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32q80a2g In reply to <a href='/nevent1qqsgxt2hnupcvhn740v8r2wmmxkfahl8h8qlh4uvc2e5j4qd3xm8sps5j9xg8'>nevent1q…9xg8</a><br/>_________________________<br/><br/>I would think the terms of any &#34;reasonable syntax&#34; could be encoded as natural numbers (via Gödel numbering, or writing down a text encoding and reading off the bits, etc.). Given this purported &#34;reasonable syntax&#34;, 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. 2024-11-06T19:13:53Z https://njump.me/nevent1qqsv0870ze0rcsq8trqckhx83k76ze63agtaqum2k75ru6qn93k0pzczypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32k9fur2 In reply to <a href='/nevent1qqsrp0lu3h5ncgmw3vkmhpukxragr2z6vmj9m2wt084wg0wzu4lf5vceq5u3c'>nevent1q…5u3c</a><br/>_________________________<br/><br/>The values of \(n\) in your list seem to be off by one? 2024-09-28T21:29:43Z https://njump.me/nevent1qqsggmytw0fkwchdvhrwjyxq9hdvm8m6yz27rwterwp7lp7ydd4q72szypql9m7n00r2dtt5erkpecy8quyyscrjcr843hdg39l2zkl5kfa32ys5wlw At #icfp2024 Zubin Duggal (<a href="https://well-typed.com/people/zubin/">https://well-typed.com/people/zubin/</a>) showed me this picture from a new Operations Control Center for part of Delhi&#39;s Metro system. Apparently the system status display on the giant screens is rendered with the Haskell diagrams EDSL!<br/> <img src="https://media.mathstodon.xyz/media_attachments/files/113/114/738/657/159/846/original/33adf0a78b9dd0be.jpg"> <br/> 2024-09-10T18:52:50Z