Timeline for Given A set $U$ and a set $\mathcal O$ of subsets of $U$, how many subsets of $\mathcal O$ have union $U$?
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 17, 2014 at 3:19 | comment | added | Ira Gessel | I don't know anything about the general problem. | |
| Jul 17, 2014 at 3:00 | comment | added | Gorka | Do you know if the problem has been studied before? | |
| Jul 17, 2014 at 3:00 | comment | added | Gorka | Thank you very much, so there isn't a simple formula for arbitrary $\mathcal O$? Is the problem NP hard? | |
| Jul 17, 2014 at 1:12 | history | answered | Ira Gessel | CC BY-SA 3.0 |