Thread for basic questions

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MathAndCode
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Re: Thread for basic questions

Post by MathAndCode » June 21st, 2021, 11:57 pm

Does this count as a shuttle, or is the hassled region only allowed to make 180° turns?

Code: Select all

x = 18, y = 18, rule = B2ci3aik4c5ry6a7e/S1e2aei3-cnry4eiyz5aeir6ei8
10bo$10bo$12bo$11b2o2$2b2o$3bo$2o3$8bo2bo4b2o$8bo2bo2bo$8bo2bo2b2o2$5b
2o$5bo$7bo$7bo!


Edit: What about this p84 oscillator? Is it a shuttle, or are the pseudo-catalysts, not the snowflake, considered to be hassled?

Code: Select all

x = 20, y = 5, rule = B2ci3aik4c5ry6a7e/S1e2aei3-cnry4eiyz5aeir6ei8
2o16b2o$3bo$2b2o3b3o6b2o$16bo$2o16b2o!
I have historically worked on conduits, but recently, I've been working on glider syntheses and investigating SnakeLife.

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Re: Thread for basic questions

Post by dvgrn » June 22nd, 2021, 9:26 am

MathAndCode wrote:
June 21st, 2021, 11:57 pm
Does this count as a shuttle, or is the hassled region only allowed to make 180° turns?

Code: Select all

x = 18, y = 18, rule = B2ci3aik4c5ry6a7e/S1e2aei3-cnry4eiyz5aeir6ei8
10bo$10bo$12bo$11b2o2$2b2o$3bo$2o3$8bo2bo4b2o$8bo2bo2bo$8bo2bo2b2o2$5b
2o$5bo$7bo$7bo!
Since the definition of a shuttle includes the idea of "back and forth", not "round and round", I'd say that this oscillator is a hassler but not a shuttle.
MathAndCode wrote:
June 21st, 2021, 11:57 pm
Edit: What about this p84 oscillator? Is it a shuttle, or are the pseudo-catalysts, not the snowflake, considered to be hassled?
Guess I'd still call that a shuttle, or maybe a "shuttle with pseudo-catalysts", and the pseudo-catalysts do get hassled by the snowflake. It doesn't seem like it has to be an either/or choice.

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Re: Thread for basic questions

Post by pcallahan » June 22nd, 2021, 10:26 am

dvgrn wrote:
June 22nd, 2021, 9:26 am
Since the definition of a shuttle includes the idea of "back and forth", not "round and round", I'd say that this oscillator is a hassler but not a shuttle.
I agree that a shuttle has to go back and forth. I am not sure what to call a "round and round." Even the transportation metaphor doesn't yield anything better than "loop."

The question gave me a flashback to 49P88, which I have never thought of as a shuttle, despite taking a 180° turn. I still would not call it a shuttle. The classic shuttles are p30 and p46, which are both symmetric (ignoring catalysts) and can be thought of as flips as well as 180° turns. Maybe that is too strict as a definition, but I think it's my intuition when looking at something and deciding if it's a shuttle.

The p84 above looks like a shuttle and is flip-symmetric for at least part of its trajectory.

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Re: Thread for basic questions

Post by MathAndCode » June 22nd, 2021, 10:34 am

pcallahan wrote:
June 22nd, 2021, 10:26 am
The question gave me a flashback to 49P88, which I have never thought of as a shuttle, despite taking a 180° turn. I still would not call it a shuttle. The classic shuttles are p30 and p46, which are both symmetric (ignoring catalysts) and can be thought of as flips as well as 180° turns. Maybe that is too strict as a definition, but I think it's my intuition when looking at something and deciding if it's a shuttle.
I would arguable that 49P88 is more of a shuttle than the p29 pre-pulsar hassler, which is commonly called a shuttle, because in 49P88, the hassled region goes both directions in the same way, which is impossible for any odd-period oscillator.
I have historically worked on conduits, but recently, I've been working on glider syntheses and investigating SnakeLife.

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Re: Thread for basic questions

Post by wwei47 » June 22nd, 2021, 10:59 am

MathAndCode wrote:
June 22nd, 2021, 10:34 am
I would arguable that 49P88 is more of a shuttle than the p29 pre-pulsar hassler, which is commonly called a shuttle, because in 49P88, the hassled region goes both directions in the same way, which is impossible for any odd-period oscillator.
I thought the lifewiki shuttle page implies that the P29 is valid as a shuttle.

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Re: Thread for basic questions

Post by mniemiec » June 22nd, 2021, 2:06 pm

pcallahan wrote:
June 22nd, 2021, 10:26 am
The question gave me a flashback to 49P88, which I have never thought of as a shuttle, despite taking a 180° turn. I still would not call it a shuttle. The classic shuttles are p30 and p46, which are both symmetric (ignoring catalysts) and can be thought of as flips as well as 180° turns. Maybe that is too strict as a definition, but I think it's my intuition when looking at something and deciding if it's a shuttle.
MathAndCode wrote:
June 22nd, 2021, 10:34 am
I would arguable that 49P88 is more of a shuttle than the p29 pre-pulsar hassler, which is commonly called a shuttle, because in 49P88, the hassled region goes both directions in the same way, which is impossible for any odd-period oscillator.
The LifeWiki definition is close, but I don't think it's exactly correct, at least from my memory of how the term was initially used back in the Scientific American and Lifeline days. They key feature of shuttles (as distinguished from other pulsators) is that their active regions move a substantial distance. While it's true that all of Life's common natural shuttles (e.g. queen bee and twin bees) share two additional properties (i.e. bilateral glide symmetry, and the fact that their mechanisms must be assisted by additional non-moving components), these are not necessary properties, and there are common shuttles in other rules that don't share them, e.g. ones that operate without any outside assistance, or ones with C4 rotational symmetry, or ones with no glide symmetry, that move forwards and backwards using different mechanisms (so are capable of having odd periods).

E.g. in B3/S2ae3aeijr4-ckqy there is a natural P280 suttle with C4 glide symmetry; it moves a substantial distance every 70 generations, leaving huge clean plumes, and rotating 90°. It moves sufficiently far that two copies of it can co-exist in the same area. Placing two exactly 140 generations out of phase creates a true P140 oscillator, as the plumes interact trivially, but advancing one of the shuttles a bit (e.g. 8 generations here) allows the two copies to rotate totally independent of each other, resulting in two totally separate and independent shuttle oscillators that occupy the same space.

Code: Select all

x = 81, y = 68, rule = B3/S2ae3aeijr4-ckqy
76boo$3o57b3o14bobo$obo57bobo14b3o$bboo58boo58$60b3o$60bobo13boo$62boo
12boo$77bo$76booboo$77b3o$78bo!
49P88 would qualify as a shuttle, even under the narrower Lifewiki definition, because if you look at a 3D map of its active cells, at areas occupied at opposite ends of its travels (e.g. the pi heptomino evolutions) do not overlap.

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Re: Thread for basic questions

Post by MathAndCode » June 22nd, 2021, 2:36 pm

wwei47 wrote:
June 22nd, 2021, 10:59 am
I thought the lifewiki shuttle page implies that the P29 is valid as a shuttle.
Yes. My point is that 49P88 is a shuttle, not that the p29 pre-pulsar hassler isn't.
I have historically worked on conduits, but recently, I've been working on glider syntheses and investigating SnakeLife.

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Re: Thread for basic questions

Post by pcallahan » June 22nd, 2021, 4:24 pm

MathAndCode wrote:
June 22nd, 2021, 2:36 pm
wwei47 wrote:
June 22nd, 2021, 10:59 am
I thought the lifewiki shuttle page implies that the P29 is valid as a shuttle.
Yes. My point is that 49P88 is a shuttle, not that the p29 pre-pulsar hassler isn't.
I'm not going to argue against the definition. It's just an intuitive impression. I don't see it going back and forth. However, I have no objection to its being classified as a shuttle. My biggest disappointment was never finding anything to do with it.

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Re: Thread for basic questions

Post by Entity Valkyrie 2 » June 22nd, 2021, 7:34 pm

Shuttle is usually a subcategory of hassler (unless it's a RRO or RFO or R180°O etc.)
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Re: Thread for basic questions

Post by dvgrn » June 22nd, 2021, 7:43 pm

Entity Valkyrie 2 wrote:
June 22nd, 2021, 7:34 pm
Shuttle is usually a subcategory of hassler (unless it's a RRO or RFO or R180°O etc.)
My own mental reference for the word "shuttle" is actually not the analogy with vehicles (which could perfectly well go round in a circle rather than back and forth).

A weaver's shuttle is the piece that holds the weft yard/thread/whatever, and goes back and forth across the loom. Presumably that's where the vehicular version got the name "shuttle" from -- but with those original shuttles there's a definite implication of back and forth, not round and round.

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Re: Thread for basic questions

Post by pcallahan » June 22nd, 2021, 10:37 pm

dvgrn wrote:
June 22nd, 2021, 7:43 pm
A weaver's shuttle is the piece that holds the weft yard/thread/whatever, and goes back and forth across the loom. Presumably that's where the vehicular version got the name "shuttle" from -- but with those original shuttles there's a definite implication of back and forth, not round and round.
I don't think I would have thought of that, but the idea of a shuttlecock in badminton came to mind.

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Re: Thread for basic questions

Post by pzq_alex » June 25th, 2021, 7:04 am

What is the smallest (or least recovery time) lwss reflector that can be built using current technology?
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Re: Thread for basic questions

Post by GUYTU6J » June 25th, 2021, 7:30 am

pzq_alex wrote:
June 25th, 2021, 7:04 am
What is the smallest (or least recovery time) lwss reflector that can be built using current technology?
You mean a stable one? Try connecting a LWSS-to-G/H and a G/H-to-LWSS, both accessible in the thread for stable signal converters.
(Curiously, if you were asking for MWSS the answer would be much simpler, as can be seen at the lower left corner of loafer-mwss-signal-loop.rle.gz in Golly.)

Or if periodic technology is allowed, you can have some lower recovery time, for instance this at p46:

Code: Select all

x = 32, y = 31, rule = B3/S23
22b2o5b2o$22b2o5b2o12$24bo3bo$24bo3bo3$21b2obo3bob2o$22b3o3b3o$23bo5bo
8$o2bo25b2o$4bo24b2o$o3bo$b4o!
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Re: Thread for basic questions

Post by creeperman7002 » June 26th, 2021, 1:10 pm

I just realized that the abelian sandpile model is a visual example of the laws of thermodynamics in action. Does this mean that the model could have practical applications?
B2n3-jn/S1c23-y is an interesting rule. It has a replicator, a fake glider, an OMOS and SMOS, a wide variety of oscillators, and some signals. Also this rule is omniperiodic.
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Re: Thread for basic questions

Post by Entity Valkyrie 2 » June 27th, 2021, 4:20 am

pzq_alex wrote:
June 25th, 2021, 7:04 am
What is the smallest (or least recovery time) lwss reflector that can be built using current technology?
These have a recovery time of 78:

Code: Select all

x = 123, y = 79, rule = B3/S23
93b2o$93bobo$95bo4b2o$91b4ob2o2bo2bo$91bo2bobobobob2o$94bobobobo$95b2o
bobo$99bo2$85b2o$15b2o11bo57bo7b2o$15b2o10bobo56bobo5b2o17bo$27bobo2b
2o3bo49b2o22b3o$26b2ob2o2bo2bobo12bo58bo$30bobo3bobo10b3o16bo41b2o$26b
2obo2b4obo10bo18bobo$26b2obobo3bo12b2o17bobo$30bobo3bo28b3ob2o47b2o$
31bobo3bo26bo54bo$32bo3b2o27b3ob2o26b2o20bob2o$57b2o8bob2o26bo13b2o4b
3o2bo$58bo39b3o10b2o3bo3b2o$58bobo39bo15b4o$23b2o34b2o39bob2o15bo$23b
2o73b2obobo12b3o$8b2o88bo2bo13bo$7bo2bo89b2o14b5o$6bob2o110bo$6bo111bo
$5b2o111b2o$20b2o$20bo$21b3o24b2o$23bo11b2o11b2o$2o15b2o17bo$bo15bo3bo
11b3o4bo49bo$bobo11bobo2bobo10bo6b3o45b3o$2b2o11b2o3bobo20bo43bo$9bo9b
2ob3o17b2o43b2o$8bobo14bo$8bobo8b2ob3o43b2o$9bo9b2obo11b2o33bo4b2o$34b
o31b3o5b2o$31b2obo31bo$20b2o9bo2b3o4b2o$20bobo9b2o3bo3b2o$12b3o7bo2bo
8b4o$6b2o4bo2bo5b2obobo7bo15b2o$7bo4bo9bo2bo9b3o12bobo$4b3o5bo7bobo15b
o13bo$4bo8bobo4b2o11b5o14b2o$33bo$35bo35b2o$34b2o36bo24b2o$72bobo23bo$
62bo10b2o17b2ob3o$60b3o29b2obo$59bo$59b2o$44b2o$45bo$45bob2o$46bo2bo$
47b2o45b2o$62b2o30b2o$62b2o5$70bo3b2o$69bobo3bo11b2o$65b2obobo3bo12bo$
65b2obo4bo14b3o$69b5obo14bo$52b2o7b2obob2obo4bobo$53bo7bob2obo2bob3o2b
o$50b3o15b2obo4b2o$50bo!

Code: Select all

x = 127, y = 99, rule = B3/S23
23bo$23b3o15b2obo4b2o$26bo7bob2obo2bob3o2bo$25b2o7b2obob2obo4bobo13bo$
42b5obo12b3o$38b2obo4bo13bo$38b2obobo3bo12b2o27bo$42bobo3bo38b3o$43bo
3b2o37bo$86b2o$69b2o$70bo$70bobo$3bo31b2o34b2o$2bobo6bo23b2o$3bo6bobo
7b2o$10bobo6bo2bo$b5o3b2ob3o3bob2o$o2bo2bo8bo2bo$2o3b2o2b2ob3obobo$9b
2obo3bob2o12b2o$16bo15bo$14b3o16b3o24b2o$13bo21bo11b2o11b2o$o2bo9b2o
33bo$4bo40b3o59bo$o3bo40bo32b2o5b2o20b3o$b4o74bo5bo24bo$76b3o7b3o20bob
o$10b2o64bo11bo20bobo$9bo2bo97bo$10b2o113b2o$2b2o121bo$bobo119bobo$bo
121b2o$2o$13b2o$13bo$14b3o$16bo$105b2o$104bobo$104bo18b2o$103b2o7b2o9b
o$112b2o10bo$123b2o$120b2o$120b2ob2o$123bo$120b2o3bo$119bo2b4o$48b2o3b
2o17bo45bobobo$48b2o2bob3o13b3o27bo18bo2bob2o$52bo4bo11bo30b3o19bobo$
48b4ob2o2bo11b2o32bo17b2obo$48bo2bobobob2o22b2o19b2o14bobo2bo$51bobobo
bo23bo15bo20b2o2bo$52b2obobo21bobo15b3o23b3o$56bo22b2o19bo24bo$99b2o$
42b2o$16bo26bo7b2o$16b3o24bobo5b2o$19bo24b2o$18b2o$96b2o$96b2o17b2o$
10b2o103b2o$10bo$7b2obo$7bo2b3o4b2o35b2o60b2o$8b2o3bo3b2o35bo61bo$10b
4o41b3o45b2o12b3o$10bo15b2o29bo28b2o16bo14bo$11b3o12bobo2b2o53bo14b3o$
14bo13bo2bo29b2o24b3o11bo$9b5o14b3o2bo26bobo26bo$9bo21b3o26bo$11bo18bo
28b2o$10b2o18b2o7$20b2o$19bobo5b2o$19bo7b2o$18b2o2$32bo$28b2obobo$27bo
bobobo$24bo2bobobobob2o$24b4ob2o2bo2bo$28bo4b2o$26bobo$26b2o!

Code: Select all

x = 171, y = 72, rule = B3/S23
71bo$71b3o15b2obo4b2o$74bo7bob2obo2bob3o2bo$73b2o7b2obob2obo4bobo$90b
5obo$86b2obo4bo$86b2obobo3bo$90bobo3bo$91bo3b2o44bo$141b3o$111bo32bo$
109b3o13bo17b2o$108bo16b3o$83b2o23b2o18bo$83b2o42b2o$68b2o$67bo2bo$66b
ob2o$66bo$65b2o$80b2o$80bo36b2o$81b3o33b2o$15b2o11bo54bo10b2o$15b2o10b
obo63bobo$27bobo2b2o3bo55bo$26b2ob2o2bo2bobo53b2o10b2o$30bobo3bobo66bo
$26b2obo2b4obo64b3o9b2o36b2o$26b2obobo3bo66bo11bo19b2o16bobo$30bobo3bo
78b3o15bobo18bo$31bobo3bo79bo15bo20b2o$32bo3b2o58b2o11bo22b2o$51bo44b
2o10bobo$49b3o56bobo2b2o3bo$48bo58b2ob2o2bo2bobo$23b2o23b2o61bobo3bobo
$23b2o82b2obo2b4obo21bo2bob2o$8b2o97b2obobo3bo23b4obo$7bo2bo100bobo3bo
27bobo$6bob2o102bobo3bo23b2o2b2o$6bo106bo3b2o23bo$5b2o125bo10bo$20b2o
38b2o68b3o9b2o2bo$20bo38bo2bo66bo16b3o$21b3o36b2o42b2o23b2o18bo$23bo
11b2o49b2o16b2o42b2o$2o15b2o17bo49bo2b2o$bo15bo3bo11b3o6bob2o17b2o22b
2o2bo$bobo11bobo2bobo10bo6b3ob2o17bo26bo$2b2o11b2o3bobo16bo24b3o20b3o$
9bo9b2ob3o15b3ob2o20bo19bo$8bobo14bo16bobo41b2o13b2o$8bobo8b2ob3o17bob
o4b2o50bo36b2o$9bo9b2obo20bo6bo51b3o33b2o$47b3o54bo10b2o$47bo66bobo52b
2o$20b2o92bo54b2o$20bobo90b2o10b2o$12b3o7bo2bo50b2o48bo$6b2o4bo2bo5b2o
bobo48bobo5b2o38b3o9b2o$7bo4bo9bo2bo49bo7b2o38bo11bo19b2o$4b3o5bo7bobo
51b2o60b3o15bobo$4bo8bobo4b2o116bo15bo$88bo64b2o$84b2obobo$83bobobobo$
80bo2bobobobob2o$80b4ob2o2bo2bo$84bo4b2o$82bobo$82b2o!
These have a bigger recovery time:

Code: Select all

x = 142, y = 62, rule = B3/S23
65bo$65b3o15b2obo4b2o$68bo7bob2obo2bob3o2bo$67b2o7b2obob2obo4bobo8b2o
7b2o$84b5obo9b2o7bobo$80b2obo4bo18bobob3o$80b2obobo3bo17b2o5bo$84bobo
3bo22b2o$85bo3b2o5$77b2o$77b2o$62b2o$61bo2bo$15b2o11bo31bob2o$15b2o10b
obo30bo$27bobo2b2o3bo21b2o69b2o$26b2ob2o2bo2bobo35b2o54b2o$30bobo3bobo
35bo$26b2obo2b4obo37b3o$26b2obobo3bo41bo$30bobo3bo$31bobo3bo86b2o3b2o$
32bo3b2o86b2o3b2o$51bo46b2o8bo$49b3o47bo8b3o$48bo47b3o12bo$23b2o23b2o
46bo13b2o$23b2o$8b2o$7bo2bo$6bob2o$6bo87bo$5b2o87b3o$20b2o38b2o35bo$
20bo38bo2bo21bo11b2o11b2o$21b3o36b2o20b3o24b2o$23bo11b2o44bo$2o15b2o
17bo44b2o$bo15bo3bo11b3o6bob2o17b2o2bo$bobo11bobo2bobo10bo6b3ob2o17bo
3b3o$2b2o11b2o3bobo16bo24b3o3bo$9bo9b2ob3o15b3ob2o21b2o2bo$8bobo14bo
16bobo21bo2b2o$8bobo8b2ob3o17bobo4b2o15b2o16b2o52b2o$9bo9b2obo20bo6bo
3b2o28b2o52bobo$47b3o4bo85bo$47bo7b3o82b2o$20b2o35bo$20bobo$12b3o7bo2b
o66bo3b2o$6b2o4bo2bo5b2obobo64bobo3bo37b2o$7bo4bo9bo2bo61b2obobo3bo12b
2o24bo$4b3o5bo7bobo64b2obo4bo13bo26b3o$4bo8bobo4b2o69b5obo12b3o25bo$
74b2o7b2obob2obo4bobo13bo11b2o$75bo7bob2obo2bob3o2bo24bobo$72b3o15b2ob
o4b2o23bo$72bo49b2o!

Code: Select all

x = 65, y = 112, rule = B3/S23
51b2o$52bo$36bo15bobo$30bo5b3o14b2o$30b3o6bo7b2o$33bo4b2o7b2o$32b2o2$
63b2o$63b2o3$25b2o$25b2o10b2o$37bobo$38bo4$37b2o$37bo$38b3o18b2o$40bo
18bo$60b3o$62bo6$25b2o$26bo28b2o$3b2o21bobo26b2o$4bo22b2o$2bo$2b5o14b
2o$7bo13bo$4b3o12bobo$3bo15b2o$3b4o$b2o3bo3b2o$o2b3o4b2o$2obo25b2o$3bo
24bobo$3b2o23bo$27b2o7b2o$35bobo$11b2o22bo$12bo21b2o$9b3o$9bo2$20bo39b
2o$20b3o37b2o$23bo$14b2o6b2o$14b2o$22b2o$22b2o2$4b2o$5bo55b2o$5bobo53b
obo$6b2o55bo$63b2o9$3b2o26b2o$2bo2bo2b2o22bo6b2o$3b2o2bobo19b3o7bo$5b
2o16b2o4bo7bobo$5bo17bo13b2o$2b2obo2bo15b3o$2bob2obobo16bo$6bobo$3b2o
2bo$b3ob2o$o$b3ob2o$3bob2o30bo$29bo6bobo$13b2o13bobo6bo$13b2o7b2o4bobo
$22bo3b3ob2o3b5o$20bobo2bo8bo2bo2bo$20b2o4b3ob2o2b2o3b2o$28bob2o$24bo$
24b3o$2o25bo$2o24b2o9bo2bo$36bo$36bo3bo$36b4o2$16bo12b2o$15bobo10bo2bo
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dvgrn
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Re: Thread for basic questions

Post by dvgrn » June 27th, 2021, 9:25 am

Entity Valkyrie 2 wrote:
June 27th, 2021, 4:20 am
pzq_alex wrote:
June 25th, 2021, 7:04 am
What is the smallest (or least recovery time) lwss reflector that can be built using current technology?
These have a recovery time of 78...
Side note mostly to pzq_alex: these do technically work at p74 and p75 as well, as usual for fast syringe-based stuff. It's just that p76 and p77 don't work, so p78 is the lowest "safe" recovery time.

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Re: Thread for basic questions

Post by MathAndCode » June 27th, 2021, 2:21 pm

The LifeWiki article about the queen bee shuttle seems to state that the version of the queen bee shuttle where the beehives are eaten by blocks was found in 1970, but the LifeWiki article about the fishhook states that the fishhook was not even discovered as a still life until 1971. Does that mean that using the term eater 1 to refer to a fishhook is incorrect?
I have historically worked on conduits, but recently, I've been working on glider syntheses and investigating SnakeLife.

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Re: Thread for basic questions

Post by dvgrn » June 27th, 2021, 3:53 pm

MathAndCode wrote:
June 27th, 2021, 2:21 pm
Does that mean that using the term eater 1 to refer to a fishhook is incorrect?
No, it's correct. The term "eater 1" refers to a fishhook.

I think you're really asking whether "eater 1" was the first eater that was discovered. It definitely wasn't, any more than "eater 5" is unambiguously the fifth eater that was discovered. But that's totally okay. I don't think any of the LifeWiki eater-N pages say that eaters 1 through 5 are numbered in strict chronological order of discovery; in particular, eater 3 was pretty definitely discovered after eater 4.

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Re: Thread for basic questions

Post by MathAndCode » June 27th, 2021, 4:12 pm

dvgrn wrote:
June 27th, 2021, 3:53 pm
I think you're really asking whether "eater 1" was the first eater that was discovered.
Yes, that's what I meant.
I have historically worked on conduits, but recently, I've been working on glider syntheses and investigating SnakeLife.

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Re: Thread for basic questions

Post by bubblegum » June 27th, 2021, 7:24 pm

MathAndCode wrote:
June 27th, 2021, 4:12 pm
Yes, that's what I meant.
Bad question phrasing, I see.

Besides, it's not like names have to be logical or anything. "Eater 1" doesn't mean "Eater the First", it's just its name.
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Re: Thread for basic questions

Post by blah » July 1st, 2021, 3:54 pm

Why does the Macrocell format require the depth of nodes to be specified? They can be deduced by incrementing the depth of the subnodes. Ambiguity between leaf and non-leaf nodes in 3+ state rules can be resolved some other way, like prepending those lines with some specific character. I know .mc isn't supposed to be maximally optimised for size, but this seems particularly useless and wasteful, even after gzip compression.

Also, I haven't tested it on the most recent version of Golly, but on my copy, .mc files with nodes whose subnodes have the wrong depths can have weird behaviour (including crashing when you try to zoom in).
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Re: Thread for basic questions

Post by dvgrn » July 1st, 2021, 4:05 pm

blah wrote:
July 1st, 2021, 3:54 pm
Why does the Macrocell format require the depth of nodes to be specified? They can be deduced by incrementing the depth of the subnodes. Ambiguity between leaf and non-leaf nodes in 3+ state rules can be resolved some other way, like prepending those lines with some specific character. I know .mc isn't supposed to be maximally optimised for size, but this seems particularly useless and wasteful, even after gzip compression.
I've wondered the same thing from time to time. Seems like the format should either prioritize readability (in which case the nodes should be numbered explicitly so you can see which one is which!) or it should prioritize compressibility (in which case there are all kinds of tricks that would make macrocell files more compact for copying and pasting, without sacrificing machine readability at all).

(Probably we shouldn't talk about that any more, though. Otherwise Chris Rowett will notice that this is an unsolved problem and implement a new UMC format for LifeViewer.)

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Re: Thread for basic questions

Post by mniemiec » July 1st, 2021, 5:09 pm

blah wrote:
July 1st, 2021, 3:54 pm
Why does the Macrocell format require the depth of nodes to be specified? They can be deduced by incrementing the depth of the subnodes. ...
Many formats include redundant information that could ultimately be deduced from the pattern context, but that make various operations easier if they are directly available.

RLE "x = <width>, y = <height>" could be deduced by reading the entire pattern; it's useful for old programs that had to pre-allocate fixed-size arrays before filling them.

APG "xs<population>_" could be deduced by counting living cells, but it's a lot easier to sort files by doing simple string comparison.

APG "xp<period>_" and "xq<period>_" could also be deduced even more laboriously by automating the pattern until it repeats.

HRD "p<period> r<rotor cells> <height>x<width>" could all be deduced by counting the number of rows, the number of cells in each row, and the number of non-'.' cells, while the period could be computed by automating the pattern until it repeats; it's easier to search knownrotors if you don't have to do this.

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Re: Thread for basic questions

Post by blah » July 1st, 2021, 6:08 pm

mniemiec wrote:
July 1st, 2021, 5:09 pm
Many formats include redundant information that could ultimately be deduced from the pattern context, but that make various operations easier if they are directly available.

[examples]
That's a valid point (the RLE example is even used by some decoders I've written). But it raises another question: What operations are made easier by depth information? As I pointed out, it's pretty simple to calculate. Definitely far easier than RLE bounding boxes (O(N)!).

And there's another thing: Programs that interpret Macrocell files have to be much more 'serious' than programs that interpret RLEs or APGcodes or whatever HRDs are (not to say that there aren't serious programs that interpret those formats, but the barrier to entry is lower). So expecting some extra work, I think, is more reasonable. I believe a good Macrocell interpreter should be able to handle invalid input, and to do that you have to confirm the validity of the provided depths, and to do that you have to calculate them anyway, so you haven't saved time; you've actually cost yourself time.

I've been skimming over Golly's MC reading code. There seem to be two readmacrocell() functions, one in hlifealgo.cpp and the other in ghashbase.cpp. They're clearly copy/pasted (I wonder if there are any optimisations made to one that haven't been put in the other), and neither seem to actually check whether the provided depth is valid. That would explain why it crashed.

Also I think the call to zeronode() should be optimised.
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Re: Thread for basic questions

Post by mniemiec » July 2nd, 2021, 1:32 am

mniemiec wrote:
July 1st, 2021, 5:09 pm
Many formats include redundant information that could ultimately be deduced from the pattern context, but that make various operations easier if they are directly available. ...
blah wrote:
July 1st, 2021, 6:08 pm
... whatever HRDs are ...
I had only just become aware of this format a couple of days ago. It's Hickerson Rotor Descriptor format. It's used in the knownrotors file to classify oscillators by their rotors, disregarding their stators.

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