Timeline for combinatorics and permutations of adjacency
Current License: CC BY-SA 3.0
18 events
| when toggle format | what | by | license | comment | |
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| Jun 14, 2017 at 9:23 | comment | added | it's a hire car baby | ...whichever way I look at it though, it's messy! | |
| Jun 14, 2017 at 9:21 | comment | added | it's a hire car baby | @RISHABHJAIN all I can add is that this is related to the BELL numbers which enmerate partitions. An important simplifying observation is that every pair $a,b$ has to be separated by nonzero-length sequences of only $c$ and $d$. But $c$ and $d$ cannot be neighbours so every pair $a,b$ has to be separated by a nonzero sequence of all $c$ or all $d$, and vice versa - i.e. every pair $c,d$ has to be separated by a nonzero-length string of all $a$ or all $b$. | |
| Jun 13, 2017 at 21:31 | comment | added | Rishabh Jain | @RobertFrost i thought about your insight.I am thinking if i can use the symmetry in the question when all n's are equal and maybe find out a recursive relation for the next case (closed form).my approach to solving the question is similar to math.stackexchange.com/questions/137577/… this question asked previously.But i again get stuck as the combinations of all the previous relations just blows ups.Do you have any idea on how to approach this problem by using symmetry arguments maybe? | |
| Jun 13, 2017 at 18:35 | history | edited | Rishabh Jain | CC BY-SA 3.0 |
added 14 characters in body
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| Jun 13, 2017 at 14:49 | comment | added | it's a hire car baby | I think a reasonable approach might be to start with the smallest $n$, lets say it's $n_1$ for arguments sake and you have at least $n_1$ of every letter. You can then arrange those. Then take the next smallest, lets say it's $n_2$. Now you have at least $n_2-n_1$ of the remaining $3$ letters which can be arranged around them and so on. | |
| Jun 13, 2017 at 14:01 | history | reopened |
true blue anil 5xum hardmath M. Winter mlc |
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| Jun 13, 2017 at 12:11 | review | Reopen votes | |||
| Jun 13, 2017 at 14:01 | |||||
| Jun 13, 2017 at 11:52 | comment | added | true blue anil | @5xum: I believe OP has shown what he tried and where he got stuck afterwards | |
| Jun 13, 2017 at 7:44 | history | closed |
5xum amWhy C. Falcon Claude Leibovici Shailesh |
Not suitable for this site | |
| Jun 12, 2017 at 16:43 | answer | added | Throckmorton | timeline score: 1 | |
| Jun 12, 2017 at 13:48 | history | edited | Rishabh Jain | CC BY-SA 3.0 |
improved formatting and gave my approach
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| Jun 12, 2017 at 13:05 | review | Close votes | |||
| Jun 13, 2017 at 7:44 | |||||
| S Jun 12, 2017 at 12:53 | history | suggested | Prajwal Kansakar | CC BY-SA 3.0 |
latex edits
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| Jun 12, 2017 at 12:39 | comment | added | 5xum | Also, don't get discouraged by the downvote. I downvoted the question and voted to close it because at the moment, it is not up to site standards (you have shown no work you did on your own). If you edit your question so that you show what you tried and how far you got, I will not only remove the downvote, I will add an upvote. | |
| Jun 12, 2017 at 12:39 | comment | added | 5xum | Hi and welcome to the site! Since this is a site that encourages and helps with learning, it is best if you show your own ideas and efforts in solving the question. Can you edit your question to add your thoughts and ideas about it? | |
| Jun 12, 2017 at 12:38 | comment | added | wonko | what did you try so far? any progress? | |
| Jun 12, 2017 at 12:36 | review | Suggested edits | |||
| S Jun 12, 2017 at 12:53 | |||||
| Jun 12, 2017 at 12:33 | history | asked | Rishabh Jain | CC BY-SA 3.0 |