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Rich’s p16 came in at 11th place in the 2016 Pattern of the Year awards. First place was never even a remote possibility, not in a year that produced the Caterloopillar and the Copperhead. (I actually thought the latter would win handily, but I guess that’s just my relative lack of interest in engineered spaceships showing.)
A week or so ago, a better recipe was found for the last still life on Mark Niemiec's list of expensive 14-bit syntheses. Now all 14-bit still lifes can be constructed with less than 14 gliders -- less than 1 glider per bit, as the old saying goes.
Catagolue results continue to be very useful in finding new recipes.
#C 12-glider synthesis for the last 14-bit still life,
#C snake bridge snake / 12.105, which had previously cost at least
#C one glider per bit.
#C Goldtiger997, 6 October 2016, optimized by Mark Niemiec on 7 October.
x = 79, y = 71, rule = LifeHistory
#C [[ AUTOFIT AUTOSTART GPS 25 LOOP 150 ]]
UPDATE: The next challenge along these lines was to similarly reduce 15-bit still life costs to below 1 glider per bit. The process started later in the same forum thread, and was completed on November 19, 2016, with the following 14-glider synthesis:
#C 14-glider synthesis for the last 15-bit still life
#C which had previously cost at least one glider per bit.
#C Extrementhusiast, 19 November 2016
x = 48, y = 38, rule = B3/S23
#C [[ AUTOFIT AUTOSTART GPS 25 LOOP 150 ]]
UPDATE 2: The next project involved a similar reduction for 16-bit still life recipes. The official project kickoff was on December 16, 2016, when 443 of the 3,286 16-bit still lifes had no synthesis in less than 16 gliders in Chris Cain's database. It concluded successfully on May 24, 2017.
If you run them in B37c/S23, the pre-loaf stabilizes quickly, but the pi takes a while — and some space. It needs 110 generations to settle down.
If you run them in B37e/S23, though, the pre-loaf just becomes a loaf immediately and the pi stabilizes much more quickly, in only 23 generations, and without spreading out so much.
That lame explanation seems even more lame when you consider this: The non totalistic rule B37c/S23 (meaning birth occurs if there are 3 live neighbors, or if there are 7 live neighbors with the dead neighbor in the corner of the neighborhood) is explosive, but B37e/S23 (birth occurs if there are 3 live neighbors, or if there are 7 live neighbors with the dead neighbor on the edge of the neighborhood) isn’t.
Here’s an even more perplexing (to me, at least) instance of different CA behavior under similar-but-different rules. Consider this 32 x 32 soup: B36/S23 is a Life-like rule sometimes called HighLife. Many objects behave the same way as in Life; in particular, blocks, loaves, boats, and beehives are still lifes; blinkers are p2 oscillators; gliders are c/4 diagonal spaceships. So after 378 generations in B36/S23 when that soup looks like this, it’s stabilized: B38/S23 has no nickname I know of. Under that rule, the same soup stabilizes in 483 generations: And in B37/S23… here’s what it evolves to after 10,000 generations:Population 17,298 and growing, presumably forever.
Fairly typical. I’ve seen some soups take several thousand generations to stabilize in B38/S23, and I’ve seen a few — very few — stabilize in B37/S23. But most soups stabilize in 1000 generations or so in B36/S23 and B38/S23… and almost all soups explode in B37/S23.
Does that make any sense to you? Explain it to me, then.
It surprises me how hard it can be to guess what kind of behavior a given CA rule will produce. There are some things that are fairly obvious. For instance, under a rule that doesn’t include births with fewer than 4 live neighbors, no pattern will never expand past its bounding box. (Any empty cell outside the bounding box will have no more than 3 live neighbors, so no births will occur there.)
But beyond a few observations like that, it’s hard to predict. At least for me.
Consider the rule B34/S456, for a semi random example. Start with a 32 by 32 soup at 50% density: Then let it run for 1000 generations. It expands to a blob 208 by 208 in size, population 21,132:But change the B34/S456 rule to B3/S456 or B4/S456 — removing one number or the other from the birth rule — and either way, the same initial configuration dies.
Here’s another big spaceship evolving from a soup. The rule here is B358/S23, and the soup has D2_+1 symmetry.
x = 143, y = 41, rule = B358/S23 47b2o$49bo$51b2o$45bo7bo32bo$b2o21bo20bob3o36bo35b3o$o2bo19bobo24bo3bo 30bobo34bo14b2o$bobo18bo3bo14bobo5b2o32bo5bo32bo4bo12b2o$5bob3o12bo3bo 17b3obo2b4o2bo24bo7bo17bobo12bo12b2obo2bo$7bo2bo12bobo15bo3b2ob2o3bo3b o25bobobobo18bobo14bo2bo4bo3bob2obo$3b5ob2o13bo15bo2b3o11b2o25bo3bo35b 2o2bo4bo3bo2b3o$2bo2bo36bo3b2o3b2o4bobo19b2o34b2o6bo4bo4bo$2bo2b2o5b2o 30bob2o8bo2bo19b2o4bobo20bobo4b2o6bo4b2o4bo2bo$6bo6b2o2bo22b3ob2o2bo7b o27b2ob2o19bobo13bo4bo6bo$4bob2o4b2o2bo3bo23b2o2bo7bobo26b3o37bo$2bobo 12bobobo24bobobo6bo28bo39bo$2bobo4bo7bob4o25b2o$4bo3bo3b2o4b2obo26b2o$ 8b3ob2o3b2obo$18bo4$18bo$8b3ob2o3b2obo$4bo3bo3b2o4b2obo26b2o$2bobo4bo 7bob4o25b2o$2bobo12bobobo24bobobo6bo28bo39bo$4bob2o4b2o2bo3bo23b2o2bo 7bobo26b3o37bo$6bo6b2o2bo22b3ob2o2bo7bo27b2ob2o19bobo13bo4bo6bo$2bo2b 2o5b2o30bob2o8bo2bo19b2o4bobo20bobo4b2o6bo4b2o4bo2bo$2bo2bo36bo3b2o3b 2o4bobo19b2o34b2o6bo4bo4bo$3b5ob2o13bo15bo2b3o11b2o25bo3bo35b2o2bo4bo 3bo2b3o$7bo2bo12bobo15bo3b2ob2o3bo3bo25bobobobo18bobo14bo2bo4bo3bob2ob o$5bob3o12bo3bo17b3obo2b4o2bo24bo7bo17bobo12bo12b2obo2bo$bobo18bo3bo 14bobo5b2o32bo5bo32bo4bo12b2o$o2bo19bobo24bo3bo30bobo34bo14b2o$b2o21bo 20bob3o36bo35b3o$45bo7bo32bo$51b2o$49bo$47b2o!
It goes left to right (right to left in the original soup) at speed 36c/72.
Again, the way this comes about is through development of a small seed. In this case at generation 83 you get a couple of these objectswhich in four generations recur, inverted, but with some debris.By itself, this seed becomes a 36c/72 puffer.But two of them, mirror images at just the right separation, have their smoke trails interact in such a way as to extinguish them, and the result is a spaceship. If you start with this pair
Hot on the heels of Rich’s p16, here’s a period 18 oscillator, once again found using apgsearch. It even bears a family resemblance to the p16: D2_+1 symmetry and shuttle behavior. But… it doesn’t work in Life (B3/S23). It works in B357/S23.
x = 13, y = 5, rule = B357/S23 b2ob2ob2ob2ob$o4bobo4bo$5bobo5b$4bo3bo4b$3b3ob3o3b!
The stubby wiki page says I discovered it, which is silly of course: all I did was install apgsearch and run it looking at D2_+1 soups in standard Life (B3/S23). I was asleep when it found this and woke up to find it’d been tweeted, retweeted, reported on the forum, used to make a smaller p48 gun, deemed awesome, and written up on the wiki.
Tim Coe has found a symmetrical spaceship with a new speed, 3c/7 (left, below) after a series of searches that took a total of "one or two months". At 29 cells wide, it is the minimum width odd symmetric spaceship -- an exhaustive width 27 search was run some time ago by Paul Tooke. The author seems to have officially chosen a name of "Spaghetti Monster" for the new 3c/7 spaceship.
Matthias Merzenich has pointed out that two of these spaceships can support a known 3c/7 wave (right, below).
#C 3c/7 FSM spaceship: Tim Coe, 11 June 2016
#C Period-28 3c/7 wave found by Stephen Silver on Feb. 2, 2000
x = 187, y = 139, rule = B3/S23
#C [[ AUTOFIT AUTOSTART GPS 4 ]]
This is the twenty-second spaceship velocity constructed in Conway's Life -- counting each of the four infinite families of spaceships (Gemini, HBK, Demonoid, Caterloopillar) as one velocity each.