Timeline for First isomorphism theorem for sets?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Sep 24, 2021 at 15:34 | comment | added | Nick S | Probably of topic: I like to point out to students that given a relation $aRb$ on a set $A$, then $R$ is an equivalence relation if and only if there exists some function $f$ from $A$ to some set $B$ such that $aRB \Leftrightarrow f(a)=f(b)$. To me this makes the factorisation more natural. | |
| Sep 24, 2021 at 5:49 | history | became hot network question | |||
| Sep 24, 2021 at 1:17 | comment | added | Joe Silverman | @LSpice Ha, my mistake, it seems. So the desk pigeonholes were named after the individual units in structures that people built to house pigeons. I guess that makes sense. Thanks. | |
| Sep 24, 2021 at 0:47 | comment | added | LSpice | @JoeSilverman, re, I'm pretty sure pigeonholes as currently understood are named for the pigeonholes that really did hold pigeons: see sense 1 of pigeonhole. | |
| Sep 23, 2021 at 23:13 | answer | added | Keith Kearnes | timeline score: 4 | |
| Sep 23, 2021 at 22:05 | comment | added | Joe Silverman | @Carl-FredrikNybergBrodda But if pigeons come in flocks, what do students come in? :) Maybe cohorts? Personally, I like the name "flock lemma" (yes, I'm old fashioned), but then the elements of T should not be (pigeon)-holes, since letters and correspondence go into pigeonholes, not pigeons! Hmmm... To be honest, I'm not sure that I know where flocks of actual pigeons congregate, other than maybe rooftops and around park benches where crumbs are being distributed. | |
| Sep 23, 2021 at 21:45 | comment | added | Carl-Fredrik Nyberg Brodda | Instead of pigeons and holes, how about something a bit more up to date: students and breakout rooms. Even better if you give this course over Zoom. | |
| Sep 23, 2021 at 21:40 | comment | added | Benjamin Steinberg | The first isomorphism theorem is called that in universal algebra and sets are universal algebras. | |
| Sep 23, 2021 at 21:30 | history | asked | Pace Nielsen | CC BY-SA 4.0 |