Hey R.E.

Nobody really picked this up, but I experimented for a little and produced this 
code to produce the Wolfram 30 puzzle, thought it might be useful for anyone 
wanting to explore.
Turns out to be a nice use case for 3 u;._3 to extract length 3 subsets from a 
list as in a tessellation …

The following can be pasted into a script (careful of quotes copying in here):

=====================================================================
load 'viewmat'

NB. Wolfram’s 8 match cases for the existing row
NB. NB. Convert each match case in base 2 (eg 1 1 1) to an integer (eg 7) as 
this is then faster to look up in addrow
cases=: #.8 3$1 1 1, 1 1 0, 1 0 1, 1 0 0, 0 1 1, 0 1 0, 0 0 1, 0 0 0
value=: 0 0 0 1 1 1 1 0

addrow=: 3 : 0
 lastrow=. ,>_1 {. y
 NB. Calculate the #. of length 3 subarrays from the lastrow, then look up in 
cases and return corresponding value to create newrow
 newrow=. value {~ cases i. 3 #.;._3] 0 0,lastrow,0 0
 y,<newrow
)

view=:3 : 0
 (|.-i.1{.$ mat)|."0 1 mat=:>y
)

diagonal =:3 : 0
 (<0 1)|: y NB. Return diagonal of matrix y
)

smoutput 'To run for example ...'
smoutput ' viewmat view addrow^:50 <1'
=====================================================================

So the sample line above:

   viewmat view addrow^:50 <1

reproduces the graphic triangle shown in the first link you gave below …

I did not spend much time on analysing the centre column (which in my case as I 
maintain each row as a list, may be found using diagonal as here;

   diagonal >addrow^:6 <1
1 1 0 1 1 1 0

Hope others find this useful.

@Cliff Reiter: maybe even scope to consider as another chaotic instance as 
Woflram suggest…/Rob

> On 2 Oct 2019, at 6:49 pm, R.E. Boss <[email protected]> wrote:
> 
> This was submitted in math-fun
> 
> https://rule30prize.org
> https://writings.stephenwolfram.com/2019/10/announcing-the-rule-30-prizes
> 
> 
> R.E. Boss
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm

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