FINALLY! The TRUTH about monads that Big FP doesn't want you to know! Written by a REAL programmer who still uses COBOL like a PROFESSIONAL!

We've added two new modules (Abelian groups, really): $latex \mathbb Q/\mathbb Z$ and $latex \mathbb R/\mathbb Z$. The first one is the torsion subgroup of the second one. The second one is isomorphic to the group of complex numbers of modulus 1.

You might not know Ezra Klein's name, but I would recommend you check out his YouTube channel's videos. (Did you know his dad is a mathematician by the name of "Abel Klein"? It was probably unintentionally mathy, but it is fun to think that it was destiny: Abel/Klein) Just to name a few random qualities that I like about his shows: …

Recently on math.stackexchange.com, someone asked if there was a ring $latex R$ for which every other ring appears as $latex \mathrm(End)(M_R)$ for some $latex R$-module $latex M$. A nice example was suggested by user MatheinBoulomenos based on an article Göbel, Rüdiger, and Daniel Simson. "Rigid families and endomorphism algebras of Kronecker modules." Israel Journal of Mathematics 110.1 (1999): 293-315. So, $latex \Gamma_2(\mathbb Z)$ is…

YouTube video by The Ezra Klein Show

YouTube video by Veritasium

The 200th ring has been chosen! Thanks JoseBrox for suggesting it!

YouTube video by Common Scholar

The managing editors and entire editorial board of Mathematical Logic Quarterly, a Wiley title, have resigned, citing “unilateral decisions” by the publisher “that affected the editorial process.”&…

Memorial Resolution of the Faculty of the University of Wisconsin-Madison On the Death of Professor Emeritus I. Martin Isaacs On Monday, February 17, 2025, the UW math department lost an outstanding r...

David Geier and his father Mark speak to Fox News in 2022. When it comes to conversations about vaccines and autism, we always have plenty to write about. And the latest news that the Trump adminis…

If you get updates on this site, you may have noticed recently we surpassed 200 ring ids. Last time when the 100th ring came around, we had a special user submission event. This is how we got $latex R_{100}$ from MatheinBoulomenos. Let's keep that "centannular" tradition going by having another round of user submissions for the empty spot at id 200.

Five rings have been added to prove two interesting things about rings with internal cancellation (IC rings)

Three new rings have been added which demonstrate a few things about the Ore condition

Recently suggested by LukasHeger, this example fills a longstanding gap we had open in the database for a J-1 ring that is not J-2. The fact that it's also a principal ideal domain makes it interesting, because they are a very "nice"c class and one doesn't expect them to be missing properties. Unfortunately at this time I do not have access to the construction details... but if you have the access you can look up the original source linked above.

I don't mean facts about the mythical undead creature. In this case, it refers to ideas that persist beyond the end of their natural life (that is, after they have been shown to be faulty.) Why such things "linger" or prove to be "sticky" probably involves a lot of confirmation bias. How they even come to the surface often involves poor practices by media outlets concerning science.

$latex R_{192}$ is an example of what has come to be called a Magnus algebra. You can think of it as a noncommutative formal power series ring. My favorite addition this time though is $latex R_{193}$, the so-called ring of integer-valued polynomials (thanks to github user dyunov for recommending it.) This ring sits between $latex \mathbb Z[X]$ and $latex \mathbb Q[X]$.

Counterexamples to Jacobson's question about prime von Neumann regular rings, and π-regularity is not Morita invariant