Timeline for "Downward closed" relation on a poset
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 26, 2016 at 21:44 | comment | added | Paul Taylor | Relations for which $x'\leq x R y\leq y'\Longrightarrow x' R y'$ are most certainly a very common kind of animal. Mappings $X\to T X$ for any endofunctor of any category are another very common kind of animal, called a coalgebra, which enough people study to run a conference series. | |
| Apr 25, 2016 at 17:44 | comment | added | Gejza Jenča | This is just a set-mapping $P\to D(P)$, where $D(P)$ is the set of all downward closed sets of $P$. Never heard of anyone studying this strange kind of animal. However, if you would want to know something about isotone mappings $P\to D(P)$, that would be another story, of course. | |
| Apr 23, 2016 at 17:42 | comment | added | Goldstern | Downward closed sets are sometimes called "order ideals". | |
| Apr 23, 2016 at 16:38 | history | asked | fosco | CC BY-SA 3.0 |