This is a collection of interesting patterns for my "Just Friends" rule.
This rule is derived from the simple B2/S12 rule, but removes those B2
situations which made almost all objects explode.  The result is a nicely
behaved universe with interesting behavior.

The rule is symmetrical but non-totalistic, as follows:

A cell stays alive only if it has 1 or 2 live neighbors (in any position).
A cell is born only if it has exactly two live neighbors which are not
adjacent vertically or horizontally.

So in the following figure, the central cell is born if there are live
cells at any two cells marked ac, ad, ae, af, ag, bd, be, bf, bg, bh,
ce, cf, cg, ch, df, dg, dh, eg, eh, or fh.
      abc
      hid
      gfe
			
Another way of explaining this is that there is birth for two parents,
but only if they are not "too intimate" with each other by being adjacent
orthogonally to each other.

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Some features of this rule:

Long rows of cells are relatively stable.

There are two small c/6 diagonal gliders which occur spontaneously.

There is a small orthogonal c/3 wickstretcher which occurs spontaneously.

There is a period 236 rotating oscillator which occurs spontaneously.

There is a period 26 oscillator which occurs spontaneously whose phase
can be changed while turning a glider to create an effective period of 37.

Dean Hickerson has proved this rule to be omniperiodic (i.e., it contains
oscillators of all periods).  The proof of this uses the turning and
flipping components demonstrated by the p384drifter pattern.

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The files here are in the well-known RLE format, except that they have
an extra header which specifies the non-totalistic rule in a format known
to my "dblife" program.  No other program I know of reads this format.

For the well-known "MCell" program, the following header defines the
"Just Friends" rule:

#MCell 3.00
#GAME Weighted Life
#RULE NW1,NN33,NE37,WW17,ME0,EE29,SW9,SS13,SE45,HI0,RS1,RS9,RS10,RS13,
#RULE RS14,RS17,RS18,RS22,RS26,RS29,RS30,RS33,RS34,RS37,RS38,RS42,RS45
#RULE ,RS46,RS50,RS54,RS58,RS62,RS66,RS70,RS74,RS78,RS82,RB10,RB14,RB3
#RULE 0,RB38,RB42,RB46,RB50,RB54,RB62,RB78,RB82
#BOARD 400x400
#WRAP 1

If one of these RLE patterns is converted into MCell format (by performing
a simple string substitution), and is appended to the above header, then
MCell will be able to run the pattern.

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David I. Bell
dbell@canb.auug.org.au
21 August 2005
