# [seqfan] Re: 9 dots puzzle

Richard Guy rkg at cpsc.ucalgary.ca
Sat Mar 12 19:26:13 CET 2011

```Sol,
Am I wrong in ascribing a solution of the generalized
``draw 4 continuous segments through 9 points'' problem
to you?  Or was it John Selfridge?  Or a collaboration?

Best wishes,  R.

On Sun, 13 Mar 2011, Dmitry Kamenetsky wrote:

> Great news. Do you know which paper it is, because he has many.
>
> Dmitry
>
> ----------------original message-----------------
> From: "Richard Guy" rkg at cpsc.ucalgary.ca
> To: "Sequence Fanatics Discussion list" seqfan at list.seqfan.eu
> Date: Fri, 11 Mar 2011 17:13:42 -0700 (MST)
> -------------------------------------------------
>
>
>> I believe that there's a paper by Sol Golomb which answers this. R.
>>
>> On Fri, 11 Mar 2011, David Wilson wrote:
>>
>>> For n = 3 through 10, 2n-2 lines suffice, although I cannot say if this
> is
>>> optimal.
>>>
>>> http://www.mathpuzzle.com/dots.html
>>>
>>> ----- Original Message ----- From: "Dmitry Kamenetsky"
>>> dmitry.kamenetsky at rsise.anu.edu.au
>>> To: "Sequence Fanatics Discussion list" seqfan at list.seqfan.eu
>>> Sent: Friday, March 11, 2011 6:00 PM
>>> Subject: [seqfan] 9 dots puzzle
>>>
>>>> Hello fans,
>>>>
>>>> Consider the 9 dots puzzle:
>>>>
>>>> http://en.wikipedia.org/wiki/Thinking_outside_the_box#Nine_dots_
>>>> puzzle
>>>> You are asked to join 9 dots (on integer coordinates) using 4 straight,
>>>> continuous lines (strokes).
>>>>
>>>> I am now wondering: what is the smallest number of strokes required to
>>>> join
>>>> all the points arranged in a NxN grid? The sequence starts with 1,3,4.
> How
>>>> to compute the rest of it?
>>>>
>>>> Sincerely,
>>>> Dmitry Kamenetsky

```