Timeline for Examples of seemingly elementary problems that are hard to solve?
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Oct 22, 2018 at 22:03 | comment | added | bof | It's hard for me to remember what was confusing me about your "hard version" when I posted my comment four years ago. Hmm. The "easy version" asks if there is an $x$ with a certain property, while the "hard version "asks if there is such a $C$ . . ." Hmm. It sounds like your "hard version" is asking about the existence of a $C$ which is a finite collection of finite sets closed under union, with $\bigcup C$ nonempty. Yes, I believe there is such a $C$. That doesn't seem so hard. | |
| Oct 22, 2018 at 21:42 | comment | added | Gerhard Paseman | @bof and others: the easy version has the answer "not always", when you pick C to have a single member, that member being the empty set. When you exclude that by having union C be nonempty, the problem is harder. Gerhard "Better Later Than Too Late" Paseman, 2018.10.22. | |
| Oct 28, 2016 at 6:50 | comment | added | მამუკა ჯიბლაძე | I join @bof - please explain. Does everybody else understand?? | |
| Oct 12, 2014 at 20:50 | comment | added | bof | I don't understand the "hard version" of Frankl's conjecture, would you mind restating it? Thanks. | |
| Sep 18, 2011 at 13:58 | vote | accept | Kyungyong Lee | ||
| Sep 18, 2011 at 17:00 | |||||
| Sep 18, 2011 at 6:46 | history | answered | Gerhard Paseman | CC BY-SA 3.0 |