[seqfan] Re: 9 dots puzzle

[Richard Guy]

Sol,
     Thanks for answering.  John died a few months ago,
after a very long period of illness.    R.

On Mon, 14 Mar 2011, Solomon Golomb wrote:

> Richard,
> I co-authored a paper with John Selfridge titled "Unicursal Polygonal Paths and Other Graphs on Point Lattices," which appeared in the Pi Mu Epsilon Journal, Fall, 1970.
> Sol Golomb
> PS. Do you know what has become of Selfridge?  Last I heard, several years ago, he was ill.
> S.
> On Mar 12, 2011, at 10:26 AM, Richard Guy wrote:
>
>> 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
>>
>
>
>