Can we substantiate this claim?

[Book]

The purpose of this thread is to have a place to note unsubstantiated assertions made on the wiki without a reference (as opposed to merely marking it "citation needed"), and see if anyone can help provide references.

Here is one such assertion: "A blockic constellation is a constellation consisting entirely of blocks. It's possible to arrange blocks in a way that can be triggered by a single glider to produce any glider constructible pattern." https://conwaylife.com/wiki/Block

[dvgrn]

The purpose of this thread is to have a place to note unsubstantiated assertions made on the wiki without a reference (as opposed to merely marking it "citation needed"), and see if anyone can help provide references.

Here is one such assertion: "A blockic constellation is a constellation consisting entirely of blocks. It's possible to arrange blocks in a way that can be triggered by a single glider to produce any glider constructible pattern." https://conwaylife.com/wiki/Block

Sure, that's a consequence of the existence of Blockic turners and splitters, plus mechanisms like the clock inserter. This topic is actually covered in a lot of detail in Chapter 5 of the Life textbook, especially starting with Section 5.7 and ending with Theorems 5.1 and 5.2.

[GUYTU6J]

The purpose of this thread is to have a place to note unsubstantiated assertions made on the wiki without a reference (as opposed to merely marking it "citation needed"), and see if anyone can help provide references.

But why did you remove the tag so hastily without providing a reference or asking for them here?
https://conwaylife.com/w/index.php?titl ... did=107829
https://conwaylife.com/w/index.php?titl ... did=107775
https://conwaylife.com/w/index.php?titl ... did=107734
https://conwaylife.com/w/index.php?titl ... did=107733

[dvgrn]

But why did you remove the tag so hastily without providing a reference or asking for them here?
https://conwaylife.com/w/index.php?titl ... did=107829
https://conwaylife.com/w/index.php?titl ... did=107775
https://conwaylife.com/w/index.php?titl ... did=107734
https://conwaylife.com/w/index.php?titl ... did=107733

Couldn't ask for them here on this thread since it didn't exist yet. It seems like the checkin comment on all of those edits answers the "why" question very clearly:

(nah, we'd have this tag on dozens of articles with discoveries from that era)

Now, it's a separate question whether everyone agrees that that's the right policy! It does seem reasonable to me that statements about the period from 1992 to 2009 can generally be assumed to be accurate, until and unless there's some internal inconsistency with other such statements elsewhere.

This is certainly a bit of a compromise, but it seems like the best we can do because of the highly awkward privacy policy of the old LifeCA mailing list. LifeCA was where 99% of new Conway's Life discoveries were recorded and discussed during that period (and 99% of Life-like CA and early OCA discoveries, for that matter). There was an agreement that, while the patterns themselves and the technical information in the emails were to be considered public domain, the emails themselves were not supposed to be republished or quoted without permission from the authors.

I tried at one point to get permission to republish from everyone active on LifeCA. But I never got responses back from a fairly large subset of the group -- and of course some LifeCA participants from the 1990s have since passed away. It used to be possible for interested people to get official access to the archives by joining the group (which required a nomination and a second). Now that LifeCA is defunct that's not really an option any more either.

-- All very unsatisfactory. By this time, many of the useful details have been extracted from the LifeCA archives and made available on the LifeWiki, but we can't easily add citations that really get back to the original source material.

Sometimes There's a Workaround
Now, David Bell has given blanket permission for republication of old emails like this one. In a case like the pre-pulsar spaceship where Ian07 added the citation-needed tag several years ago, because of not being able to find an exact reference -- it might be reasonable to reproduce David Bell's email here, and then link to this as a reasonably authoritative citation:

Subject: The c/5 pre-pulsar ships can store a bit of information

The period 30 c/5 pre-pulsar ship can be converted back and forth between its symmetrical form to its asymmetrical form. (For lack of better names for them, I will use the initials PPS for the generic pre-pulsar ship of either type, SPPS for the symmetrical form, and APPS for the asymmetrical form.)

The conversion can be done by impacting the back of the PPS by a standard spaceship. Here are several such reactions which turn a SPPS into an APPS, two of which leave a small object as debris:

Code: Select all

x = 335, y = 44, rule = B3/S23
296bo5bo$164bo5bo124b3o3b3o$163b3o3b3o122booboobooboo$162booboobooboo
122b3o3b3o$32bo5bo124b3o3b3o124bo5bo$31b3o3b3o124bo5bo97bo5boo5boo5bo
21bo5boo5boo5bo$30booboobooboo95bo5boo5boo5bo21bo5boo5boo5bo67bobboob
oobbo3bobbooboobbo17bobbooboobbo3bobbooboobbo$31b3o3b3o94bobbooboobbo
3bobbooboobbo17bobbooboobbo3bobbooboobbo63b3o4bobo3bobo3bobo4b3o13b3o
4bobo3bobo3bobo4b3o$32bo5bo93b3o4bobo3bobo3bobo4b3o13b3o4bobo3bobo3bob
o4b3o61boobbobb3oboo3boob3obbobboo13boobbobb3oboo3boob3obbobboo$4bo5b
oo5boo5bo21bo5boo5boo5bo65boobbobb3oboo3boob3obbobboo13boobbobb3oboo3b
oob3obbobboo61b3obb3o4bo3bo4b3obb3o13b3obb3o4bo3bo4b3obb3o$bbobbooboo
bbo3bobbooboobbo17bobbooboobbo3bobbooboobbo63b3obb3o4bo3bo4b3obb3o13b
3obb3o4bo3bo4b3obb3o62bobobbo15bobbobo15bobobbo15bobbobo$3o4bobo3bobo
3bobo4b3o13b3o4bobo3bobo3bobo4b3o62bobobbo15bobbobo15bobobbo15bobbobo
64bo23bo17bo23bo$oobbobb3oboo3boob3obbobboo13boobbobb3oboo3boob3obbobb
oo63bo23bo17bo23bo$3obb3o4bo3bo4b3obb3o13b3obb3o4bo3bo4b3obb3o$bobobbo
15bobbobo15bobobbo15bobbobo$bbo23bo17bo23bo19$34bo$33b3o$33boboo$34b3o
$34b3o128bo$34boo128b3o131bo$163boobo130b3o$163b3o130boobo$163b3o130b
3o$164boo131boo!

The following reaction is one which converts an APPS back into a SPPS:

Code: Select all

x = 73, y = 41, rule = B3/S23
32b3o3b3o$31bo3bobo3bo$31bo3bobo3bo$31bo3bobo3bo$32b3o3b3o$6bo3b3o5b3o
3bo23bo3b3o5b3o3bo$3boob5oboo3boob5oboo17boob5oboo3boob5oboo$boboobo5b
obobobo5boboobo3boo8boboobo5bobobobo5boboobo$o3bobo3b5ob5o3bobo3bobobb
o6bo3bobo3b5ob5o3bobo3bo$4b3o5boo3boo5b3o6boo11b3o5boo3boo5b3o$bobbob
3o13b3obobbo13bobbob3o13b3obobbo$3bo23bo17bo23bo25$34b3o$34bobbo$34bo$
34bo$35bobo!

The above reaction, and the end two of the previous reactions have the nice property that if the spaceship hits the wrong type of PPS, then it is cleanly destroyed.

What these reactions (and others like them) mean, is that a PPS can be used to store a moving bit of information. Spaceships coming from the back can used to reset the bit, or to set the bit, or to set the bit while creating a piece of debris which can then be tested to determine what the state was.

One application of this is a moving period doubling device, which accepts gliders coming in from the side, and which emits one glider for every two gliders which arrive. Very high period puffers can then be made by cascading copies of this device together.

I haven't built such a period doubling device. The naive approach of using a single period 360 c/5 LWSS rake for both the setting and resetting spaceships doesn't work because of the spacing between the LWWS's. I think you have to construct a convoy of two spaceships.

As a start on the problem, here is a period 360 forwards LWSS rake:

Code: Select all

x = 914, y = 469, rule = B3/S23
433b3o$432bobbo$435bo$435bo$432bobo104$433b3o$432bobbo$435bo$435bo$
432bobo21$120b3o3b3o344b3o3b3o$120bobo3bobo344bobo3bobo$120b3o3b3o344b
3o3b3o$$99boo5boo33boo5boo302boo5boo33boo5boo$91b4obobobo5bobobob4o17b
4obobobo5bobobob4o286b4obobobo5bobobob4o17b4obobobo5bobobob4o$90b3obob
oboobo3boboobobob3o4boo9b3oboboboobo3boboobobob3o284b3oboboboobo3boboo
bobob3o9boo4b3oboboboobo3boboobobob3o$90bo3bobo13bobo3bo3bobo9bo3bobo
13bobo3bo284bo3bobo13bobo3bo9bobo3bo3bobo13bobo3bo$91bob3o5booboo5b3ob
o5boo10bob3o5booboo5b3obo286bob3o5booboo5b3obo10boo5bob3o5booboo5b3obo
$91boo21boo17boo21boo286boo21boo17boo21boo$91b5o15b5o17b5o15b5o286b5o
15b5o17b5o15b5o$94boo15boo23boo15boo292boo15boo23boo15boo4$119bo$118bo
bo$118bobbo$111bo7boo326boo$109boo4bo330bobo$114bobbo330bo$113bo3b4o$
109boobb3obobbo$111bobo4b3o4$123boo73boo$122bobbo72bobo$123bobo72bo$
90boo5boo5boo5boo11bo12bo3b3o5b3o3bo290bo3b3o5b3o3bo24boo5boo5boo5boo$
88bo3bo3bobbo3bobbo3bo3bo19boob5oboo3boob5oboo284boob5oboo3boob5oboo
19bo3bo3bobbo3bobbo3bo3bo$88bo3bobob3o5b3obobo3bo17boboobo5bobobobo5bo
boobo280boboobo5bobobobo5boboobo17bo3bobob3o5b3obobo3bo$88bo5boobb3ob
3obboo5bo16bo3bobo3b5ob5o3bobo3bo278bo3bobo3b5ob5o3bobo3bo16bo5boobb3o
b3obboo5bo$88boob3o15b3oboo20b3o5boo3boo5b3o286b3o5boo3boo5b3o20boob3o
15b3oboo$88bo25bo17bobbob3o13b3obobbo280bobbob3o13b3obobbo17bo25bo$89b
o3bo15bo3bo20bo23bo198boo84bo23bo20bo3bo15bo3bo$90bobbo15bobbo243bobo
130bobbo15bobbo$358bo7$288boo$288bobo$288bo3$133boo5boo5boo5boo290boo
5boo5boo5boo$131bo3bo3bobbo3bobbo3bo3bo286bo3bo3bobbo3bobbo3bo3bo$131b
o3bobob3o5b3obobo3bo286bo3bobob3o5b3obobo3bo$131bo5boobb3ob3obboo5bo
286bo5boobb3ob3obboo5bo$131boob3o15b3oboo109boo175boob3o15b3oboo$131bo
25bo108bobo175bo25bo$132bo3bo15bo3bo111bo176bo3bo15bo3bo$133bobbo15bo
bbo290bobbo15bobbo6$378boo$378bobo$378bo7$177boo$176bobo$178bo5$475boo
$475boo$468boo77b3o3b3o$468bobo$98bo7bo326b3o32bo79bo5bo$92booboboboo
3booboboboo319bobbo108b3o9b3o$89b3obob3o9b3obob3o319bo112bo5bo$89bo3bo
bo5bobo5bobo3bo16boo5boo5boo5boo280bo85bo3b3o5b3o3bo23bo3b3o5b3o3bo$
93boo6bobo6boo18bo3bo3bobbo3bobbo3bo3bo275bobo83boob5oboo3boob5oboo4b
3o3b3o4boob5oboo3boob5oboo$90boo9bobo9boo15bo3bobob3o5b3obobo3bo359bob
oobo5bobobobo5boboobo13boboobo5bobobobo5boboobo$90booboo15booboo15bo5b
oobb3ob3obboo5bo358bo3bobo3b5ob5o3bobo3bo11bo3bobo3b5ob5o3bobo3bo$94bo
15bo19boob3o15b3oboo362b3o5boo3boo5b3o19b3o5boo3boo5b3o$130bo25bo335bo
3b3o5b3o3bo5bobbob3o13b3obobbo13bobbob3o13b3obobbo$131bo3bo15bo3bo327b
oo4boob5oboo3boob5oboo4bo23bo17bo23bo$132bobbo15bobbo295boo5boo24boobb
oboobo5bobobobo5boboobo$442b4obobobo5bobobob4o19bo3bobo3b5ob5o3bobo3bo
$441b3oboboboobo3boboobobob3o22b3o5boo3boo5b3o$441bo3bobo13bobo3bo19bo
bbob3o13b3obobbo$442bob3o5booboo5b3obo22bo23bo$442boo21boo$442b5o15b5o
$445boo15boo5boo3bobo$470bobbobbobbo7b3o$468bobboboobbobb4obbooboo$
468booboobobboob4oboo4bo$470b3obboboo6b6o$476bo8bobboo$482boboo$482bob
o$484bo3$454boo5boo$446b4obobobo5bobobob4o$445b3oboboboobo3boboobobob
3o$445bo3bobo13bobo3bo$446bob3o5booboo5b3obo$446boo21boo$446b5o15b5o$
449boo15boo$493bo3b3o5b3o3bo$490boob5oboo3boob5oboo$488boboobo5bobobob
o5boboobo$487bo3bobo3b5ob5o3bobo3bo$491b3o5boo3boo5b3o$488bobbob3o13b
3obobbo$490bo23bo11$528bobo$528boo$529bo53$433b3o$432bobbo$435bo$435bo
$35bo5bo346bo5bo37bobo$34b3o3b3o344b3o3b3o$33booboobooboo342boobooboob
oo$34b3o3b3o344b3o3b3o$35bo5bo346bo5bo$7bo5boo5boo5bo21bo5boo5boo5bo
290bo5boo5boo5bo21bo5boo5boo5bo$5bobbooboobbo3bobbooboobbo17bobbooboo
bbo3bobbooboobbo286bobbooboobbo3bobbooboobbo17bobbooboobbo3bobbooboobb
o$3b3o4bobo3bobo3bobo4b3o8boo3b3o4bobo3bobo3bobo4b3o282b3o4bobo3bobo3b
obo4b3o3boo8b3o4bobo3bobo3bobo4b3o$3boobbobb3oboo3boob3obbobboo7bobbo
bboobbobb3oboo3boob3obbobboo282boobbobb3oboo3boob3obbobboobbobbo7boobb
obb3oboo3boob3obbobboo$3b3obb3o4bo3bo4b3obb3o8boo3b3obb3o4bo3bo4b3obb
3o282b3obb3o4bo3bo4b3obb3o3boo8b3obb3o4bo3bo4b3obb3o$4bobobbo15bobbobo
15bobobbo15bobbobo284bobobbo15bobbobo15bobobbo15bobbobo$5bo23bo17bo23b
o286bo23bo17bo23bo$$388bo132bo5bo346bo5bo$388boo130bobo3bobo344bobo3bo
bo$387bobo$520b3o3b3o344b3o3b3o3$494bo3b3o5b3o3bo23bo3b3o5b3o3bo292bo
3b3o5b3o3bo23bo3b3o5b3o3bo$491boob5oboo3boob5oboo4b3o10boob5oboo3boob
5oboo286boob5oboo3boob5oboo10b3o4boob5oboo3boob5oboo$489boboobo5bobobo
bo5boboobo13boboobo5bobobobo5boboobo282boboobo5bobobobo5boboobo13boboo
bo5bobobobo5boboobo$86bo401bo3bobo3b5ob5o3bobo3bobobo7bo3bobo3b5ob5o3b
obo3bo280bo3bobo3b5ob5o3bobo3bo7bobobo3bobo3b5ob5o3bobo3bo$85boo405b3o
5boo3boo5b3o6bo12b3o5boo3boo5b3o288b3o5boo3boo5b3o12bo6b3o5boo3boo5b3o
$85bobo401bobbob3o13b3obobbo13bobbob3o13b3obobbo282bobbob3o13b3obobbo
13bobbob3o13b3obobbo$491bo23bo17bo23bo286bo23bo17bo23bo$$876b3o$878bo$
877bo$56boo5boo300boo5boo$6bo3b3o5b3o3bo23b4obobobo5bobobob4o225bo58b
4obobobo5bobobob4o23bo3b3o5b3o3bo$3boob5oboo3boob5oboo19b3oboboboobo3b
oboobobob3o224boo56b3oboboboobo3boboobobob3o19boob5oboo3boob5oboo$bob
oobo5bobobobo5boboobo17bo3bobo13bobo3bo223bobo56bo3bobo13bobo3bo17bob
oobo5bobobobo5boboobo$o3bobo3b5ob5o3bobo3bo17bob3o5booboo5b3obo284bob
3o5booboo5b3obo17bo3bobo3b5ob5o3bobo3bo$4b3o5boo3boo5b3o21boo21boo284b
oo21boo21b3o5boo3boo5b3o$bobbob3o13b3obobbo18b5o15b5o284b5o15b5o18bobb
ob3o13b3obobbo139b3o$3bo23bo23boo15boo290boo15boo23bo23bo141bo$569bo$$
176bo$175boo$175bobo$$497bo7bo29boo5boo5boo5boo286boo5boo5boo5boo29bo
7bo$491booboboboo3booboboboo21bo3bo3bobbo3bobbo3bo3bo226b3o53bo3bo3bo
bbo3bobbo3bo3bo21booboboboo3booboboboo$488b3obob3o9b3obob3o18bo3bobob
3o5b3obobo3bo228bo53bo3bobob3o5b3obobo3bo18b3obob3o9b3obob3o$488bo3bob
o5bobo5bobo3bo18bo5boobb3ob3obboo5bo227bo54bo5boobb3ob3obboo5bo18bo3bo
bo5bobo5bobo3bo$492boo6bobo6boo22boob3o15b3oboo282boob3o15b3oboo22boo
6bobo6boo$208bo280boo9bobo9boo19bo25bo282bo25bo19boo9bobo9boo$208boo
279booboo15booboo20bo3bo15bo3bo284bo3bo15bo3bo20booboo15booboo$49bo3b
3o5b3o3bo139bobo152bo3b3o5b3o3bo112bo15bo25bobbo15bobbo286bobbo15bobbo
25bo15bo$46boob5oboo3boob5oboo288boob5oboo3boob5oboo$44boboobo5bobobob
o5boboobo284boboobo5bobobobo5boboobo$43bo3bobo3b5ob5o3bobo3bo282bo3bob
o3b5ob5o3bobo3bo271b3o$47b3o5boo3boo5b3o290b3o5boo3boo5b3o275bo$44bobb
ob3o13b3obobbo284bobbob3o13b3obobbo273bo$46bo23bo288bo23bo$266bo$265b
oo$265bobo3$696b3o$540bo7bo149bo154bo7bo$534booboboboo3booboboboo142bo
149booboboboo3booboboboo$531b3obob3o9b3obob3o286b3obob3o9b3obob3o$40b
oo76bo412bo3bobo5bobo5bobo3bo286bo3bobo5bobo5bobo3bo$38boobo76boo415b
oo6bobo6boo294boo6bobo6boo$37bo3bo75bobo412boo9bobo9boo288boo9bobo9boo
$37bobboo490booboo15booboo288booboo15booboo$38b3o495bo15bo296bo15bo$
39bo708b3o$748bo$749bo$$356bo$355boo$355bobo3$525boo79b3o$525boo81bo$
607bo$5boo5boo5boo5boo$3bo3bo3bobbo3bobbo3bo3bo$3bo3bobob3o5b3obobo3bo
$3bo5boobb3ob3obboo5bo18bo3b3o5b3o3bo$3boob3o15b3oboo15boob5oboo3boob
5oboo$3bo25bo13boboobo5bobobobo5boboobo453b3o$4bo3bo15bo3bo13bo3bobo3b
5ob5o3bobo3bo449b3obo311b3o$5bobbo15bobbo18b3o5boo3boo5b3o342boo5boo
103booboo310bo$43bobbob3o13b3obobbo331b4obobobo5bobobob4o95booboo311bo
$45bo23bo332b3oboboboobo3boboobobob3o96bo$358bo5boo5boo5bo23bo3bobo13b
obo3bo$356bobbooboobbo3bobbooboobbo22bob3o5booboo5b3obo$354b3o4bobo3bo
bo3bobo4b3o20boo21boo$354boobbobb3oboo3boob3obbobboo20b5o15b5o$354b3o
bb3o4bo3bo4b3obb3o23boo15boo464bo5boo5boo5bo$355bobobbo15bobbobo505bo
bbooboobbo3bobbooboobbo$356bo23bo473bo7bo22b3o4bobo3bobo3bobo4b3o$389b
oo41boo414booboboboo3booboboboo16boobbobb3oboo3boob3obbobboo$389boo40b
obo411b3obob3o9b3obob3o13b3obb3o4bo3bo4b3obb3o$433bo4bobo404bo3bobo5bo
bo5bobo3bo14bobobbo15bobbobo$438boo409boo6bobo6boo19bo23bo$435bo3bo49b
oo5boo5boo5boo334boo9bobo9boo$434boo51bo3bo3bobbo3bobbo3bo3bo332booboo
15booboo$434bobo50bo3bobob3o5b3obobo3bo336bo15bo$487bo5boobb3ob3obboo
5bo24bo3b3o5b3o3bo$487boob3o15b3oboo21boob5oboo3boob5oboo$487bo25bo19b
oboobo5bobobobo5boboobo$488bo3bo15bo3bo19bo3bobo3b5ob5o3bobo3bo$362bo
5boo5boo5bo106bobbo15bobbo24b3o5boo3boo5b3o$360bobbooboobbo3bobbooboo
bbo148bobbob3o13b3obobbo$358b3o4bobo3bobo3bobo4b3o148bo23bo$358boobbo
bb3oboo3boob3obbobboo$358b3obb3o4bo3bo4b3obb3o$359bobobbo15bobbobo$
360bo23bo$412boo5boo$404b4obobobo5bobobob4o$403b3oboboboobo3boboobobob
3o$403bo3bobo13bobo3bo$404bob3o5booboo5b3obo$404boo21boo$404b5o15b5o$
407boo15boo108bo3b3o5b3o3bo$531boob5oboo3boob5oboo$529boboobo5bobobobo
5boboobo$528bo3bobo3b5ob5o3bobo3bo$532b3o5boo3boo5b3o$529bobbob3o13b3o
bobbo$531bo23bo$488boo5boo5boo5boo$486bo3bo3bobbo3bobbo3bo3bo$486bo3bo
bob3o5b3obobo3bo$486bo5boobb3ob3obboo5bo$486boob3o15b3oboo$486bo25bo$
487bo3bo15bo3bo$488bobbo15bobbo!

Are there any other uses for such a moving memory ship?

Finally, it probably would be easier if gliders could do the conversion between flavors of PPS. I haven't found any such reaction using a single glider. Perhaps a pair of gliders could do the job.

BCNU,
-dbell-

Probably Best to Request LifeCA Citations Only When Necessary
I'm open to suggestions for what we could do differently here, but it's a slightly tricky situation. It takes a fair amount of fiddling around to convert an individual email message like the one above into a forums-friendly format, so dozens or hundreds of repost requests wouldn't work very well.

No doubt we could write something to bulk-convert the posts for everyone who has given blanket permission for republication... but that's also quite a bit of work, so I'm not necessarily volunteering to take on that task either. Meanwhile, a workable alternative seems to be to switch to a "citation NOT needed" policy for most information from the 1992-2009 era, as Book has done here.

[GUYTU6J]

... In a case like the pre-pulsar spaceship where Ian07 added the citation-needed tag several years ago, because of not being able to find an exact reference -- it might be reasonable to reproduce David Bell's email here, and then link to this as a reasonably authoritative citation...

Done, thanks!

... Meanwhile, a workable alternative seems to be to switch to a "citation NOT needed" policy for most information from the 1992-2009 era, as Book has done here.

Frankly, I would rather avoid mentioning a bit of information than make an unsupported claim in some cases like the fly-by deletion&reanimation issues and the discovery of eater 4.

Can I request for the background info for almost knightship? The short introduction has failed to cover these questions that someone may be interested in: What was the search program that found the partial? How much time and software/hardware configuration was required? Were there other promising results from the same search? And so on.

[dvgrn]

Can I request for the background info for almost knightship? The short introduction has failed to cover these questions that someone may be interested in: What was the search program that found the partial? How much time and software/hardware configuration was required? Were there other promising results from the same search? And so on.

That's a tough one. Eugene Langvagen was only briefly active on LifeCA, with just half a dozen messages in 2003-4, and nothing specifically about the almost knightship -- though it can still be found on his SourceForge page.

Subject: Wickstretcher and ships in alternate Life rules (Mon Dec 15, 2003 5:16pm)
Subject: Glider-supported 7c/40 diagonal puffer (Thu Jan 8, 2004 5:40pm)
Subject: period 180/2 wick (Fri Jan 9, 2004 8:45am)
Subject: period 106 r-pentomino wall (Wed May 5, 2004 7:52pm)

I'll venture to quote here the two posts related to afind:

Subject: c/7 ship search status


There seems to be no explicit mention in the List archives of anyone trying a search for c/7 ships.

Here are some partial patterns I have:

Code: Select all

x = 20, y = 38, rule = B3/S23
2obo2bo6bo2bob2o$b2ob2o8b2ob2o$bo3b2o6b2o3bo$2b2obobo4bobob2o$4bo
2b2o2b2o2bo$4bo2bo4bo2bo$5bobo4bobo2$6bo6bo$5bo2bo2bo2bo$5bobo4b
obo$6bo6bo2$6bob4obo$5b2ob4ob2o$6bob4obo$6bo6bo$5b3o4b3o$4b3o6b3o
$3b3o8b3o$2bo14bo$2bo14bo2$2b3o10b3o2$2bobo10bobo$2bobo10bobo$2b
obo10bobo$4bo10bo$2b2o12b2o$5bo8bo$2b3o10b3o$3bo12bo2$3bo12bo$2b
obo10bobo$2bobo10bobo$3bo12bo!

Code: Select all

x = 32, y = 37, rule = B3/S23
7b3o12b3o$2bobo2bo16bo2bobo$5bo20bo$bo3b2o18b2o3bo$2o4bo18bo4b2o$
3bo3bo16bo3bo$3bobobo16bobobo$2b2o3b2o14b2o3b2o$3bobobo16bobobo$
5b3o16b3o$bo5bo16bo5bo$bo3bo20bo3bo$2bo3bo18bo3bo$4b2o20b2o$5bo2b
o14bo2bo$9bo12bo$4bo4bo12bo4bo$4bo4bo12bo4bo$5b5o12b5o$5b2o2bo12b
o2b2o$7b2o14b2o$9bobo8bobo$11b2o6b2o$12bo6bo$9bo12bo$8b3o10b3o$8b
2o2b2o4b2o2b2o$12b2o4b2o$12bo6bo$12b3o2b3o$12b3o2b3o$13bob2obo2$
14bo2bo$14bo2bo$12b2o4b2o$14bo2bo!

Code: Select all

x = 28, y = 35, rule = B3/S23
2b2o20b2o$3bobo16bobo$4bob2o12b2obo$4bob2o12b2obo$b3o2bo14bo2b3o$
6bo14bo$4bobo14bobo$b2o22b2o$2bo22bo$2o24b2o$3ob2o16b2ob3o$4bo18b
o$b5o16b5o$o26bo$b2o22b2o2$3b3o16b3o$6bobo10bobo$3bo3b3o8b3o3bo2$
5b2ob2o8b2ob2o$5b2ob2o8b2ob2o$6bob2o8b2obo$5b2ob2o8b2ob2o$9bo8bo
$8bo10bo$8b3o6b3o$10bo6bo$6bo14bo$7b3o8b3o$7b3o8b3o2$12bo2bo$10b
2o4b2o$11bo4bo!

Note that not the whole patterns are of limited width but the individual rows are. An additional restriction on each newly found row A, such that evolve(A,B,C)=D, was that A should extend no further than some amount of cells (3) beyond the total width occupied by B, C, and D.

(This I suppose is not a brand new approach - many c/4 ships seem to have been found in a similar way; a typical one "afind" gives looks like:

Code: Select all

x = 36, y = 50, rule = B3/S23
2o2b2o24b2o2b2o$bo4bo22bo4bo$3b3o24b3o$5bo24bo$3b2o26b2o$3b2o26b2o
$4b3o22b3o$5bobo20bobo$8bo18bo$6bo2bo16bo2bo$6bo3bo14bo3bo2$7b2o
2bo12bo2b2o$8b5o10b5o$11b2o10b2o$10bo14bo$8bobo14bobo$8b2o16b2o$
8b3o14b3o$8bo18bo$7bo20bo$8b2obo12bob2o$9b4o10b4o$10bobo10bobo$9b
o2b3o6b3o2bo$9b2o2b3o4b3o2b2o$9b2o3b2o4b2o3b2o$15b2o2b2o$14bo6bo
$13b2o6b2o$11bobo8bobo2$11bo3bo4bo3bo$11bo4bo2bo4bo$11bo2bo6bo2b
o$12bo3bo2bo3bo$12bob3o2b3obo3$14bo6bo$15b6o$12bob3o2b3obo$11bob
ob2o2b2obobo$11bob2o6b2obo$11b2o10b2o$11bo12bo2$8bobo14bobo$9bo16b
o$9bo16bo!

However it would be interesting for me to know exactly what that "similar way" was)

The overall strategy was to start with small width (6) and then to increase the width and revert to some previous search stage (but not the very beginning) each time the search completes. (which means I certainly miss patterns with wide rows in the leading edge)

It is thus rather tedious to describe exactly the area covered by the search; by the moment the width has been made 9 at depth around 250 (roughly corresponding to the patterns above).

ps. "afind" has been made available some time ago at http://plife.sf.net/programs/afind.cc (use gcc to compile).

Subject: Re: c/7 ship search status

On Monday 17 May 2004 12:36, Hartmut Holzwart wrote:
> Mostly to Eugene:
>
> I really liked your partial results, especially the left one which looks
> similar to the dragon. Maybe one way to effectively restrict the search for
> slow ships is to additionally require that they have a "stable head" that
> only moves in the last few generations.
>
> Did you ever try 3c/7 by the same method? You might need a bigger width for
> a start, but I expect the search to be much faster for two reasons:
>
> 1. There a fewer heads that move that fast, so this restricts the start of
> the search
> 2. Garbage has less time to catch up when there is a gap, so it is more
> likely to find a working rear end
>
> This is also supported by close observation of many searches (2c/4 vs c/4,
> 2c/5 vs. c/5), although never formally proven.
>
> I think that odd symmetric 3c/7 ships must be at least 23 cells wide, but
> do not know of results in terms of "effective width".
>
> Cheers,
> Hartmut

Yes, I have an uncompleted search for odd-symmetrical 3c/7 ships started in this way.

It hasn't run for too long so far; all I can say right now is that with current "effective" half-width 9 there occur rows with "actual" half-width up to 14 (corresponding to width 27). I guess you meant post #1767 by Paul Tooke when speaking of the minimal width 23 for the ships - if these results are still up-to-date, my search seems to do something new.

The "stable head" is pretty common when searching for slow ships, cf. this c/6 head:

Code: Select all

x = 9, y = 16, rule = B3/S23
6b2o$7bo$7bo$5bo2bo$3b5o$3bo$2bobo2$4b2o$obo2b2o$3o2$3b2o$2bo2bo$
2bobo$3bo!

So restricting the start of the search as you propose may be worth trying though technically tricky.

Eugene

[Ian07]

Now, it's a separate question whether everyone agrees that that's the right policy! It does seem reasonable to me that statements about the period from 1992 to 2009 can generally be assumed to be accurate, until and unless there's some internal inconsistency with other such statements elsewhere.

This is certainly a bit of a compromise, but it seems like the best we can do because of the highly awkward privacy policy of the old LifeCA mailing list. LifeCA was where 99% of new Conway's Life discoveries were recorded and discussed during that period (and 99% of Life-like CA and early OCA discoveries, for that matter). There was an agreement that, while the patterns themselves and the technical information in the emails were to be considered public domain, the emails themselves were not supposed to be republished or quoted without permission from the authors.

I tried at one point to get permission to republish from everyone active on LifeCA. But I never got responses back from a fairly large subset of the group -- and of course some LifeCA participants from the 1990s have since passed away. It used to be possible for interested people to get official access to the archives by joining the group (which required a nomination and a second). Now that LifeCA is defunct that's not really an option any more either.

-- All very unsatisfactory. By this time, many of the useful details have been extracted from the LifeCA archives and made available on the LifeWiki, but we can't easily add citations that really get back to the original source material.

...

Probably Best to Request LifeCA Citations Only When Necessary
I'm open to suggestions for what we could do differently here, but it's a slightly tricky situation. It takes a fair amount of fiddling around to convert an individual email message like the one above into a forums-friendly format, so dozens or hundreds of repost requests wouldn't work very well.

No doubt we could write something to bulk-convert the posts for everyone who has given blanket permission for republication... but that's also quite a bit of work, so I'm not necessarily volunteering to take on that task either. Meanwhile, a workable alternative seems to be to switch to a "citation NOT needed" policy for most information from the 1992-2009 era, as Book has done here.

Would a citation without a link be acceptable? e.g. something like:

References
1. David Bell (June 13, 1998). "The c/5 pre-pulsar ships can store a bit of information". LifeCA. Reproduced with permission of the author.

with the last part being an optional parameter.

Or, if we'd rather leave the subject line out:

References
1. Private email sent to the LifeCA mailing list by (author) on (date)

My idea here is that people who do have access to the archives will know where exactly to look to verify the information, and that people who don't will hopefully take our word for it that the info is there.

[Book]

I think we also should remember this is not Wikipedia. In many respects, our wiki has become the source of authoritative information about the earlier years if CGOL history with or without references. This, bolstered by much better referencing over the last decade, serves our community and posterity well.

I see little value in a citation needed tag that lingers in perpetuity.

[GUYTU6J]

As for the 110P62 case, it was Mattias Merzenich who added discovery information in 2018. Did it come from the oscillator collection that he is maintaining?

... And wait, I have mentioned a bunch of similar cases before:

...Many articles that Scot Ellison (Scotgot) had created a decade ago without providing a reference, and so may puzzle readers a bit about where the user had seen the patterns. Here is a list of other pages with the same issue:

• p48 pi-heptomino hassler
• p11 double-length signal injector
• Merzenich's p11
• 5blink
• Swine
• Scot's p5
• p44 traffic light hassler
• Merzenich's p18
• Voldiag
• Montana

The last two has been questioned for notability as well. So I suppose citations for pattern source will be useful for the sake of life history.

To me, the lack of response indicates how inefficient the forums communication can sometimes be.

[confocaloid]

In the book "Polyominoes" by Solomon W. Golomb, figure 151 shows a way to form a rectangle using 50 copies of a certain 11-omino. An accompanying text says

Figure 151 shows the example of order 50, found by William Rex Marshall of Dunedin, New Zealand, in 1990.*

and the footnote says

* William Rex Marshall, private communication dated 14 May 1990 and 25 November 1991.

Would this kind of reference to a private communication be helpful for referring to a certain private message without publishing the message itself?

[confocaloid]

I see little value in a citation needed tag that lingers in perpetuity.

A citation needed tag seems a good way to draw attention to unsourced non-obvious claims. I see no harm in having these tags left in articles, even for a long time. Indeed, why attempt to polish the wiki and make it look like something perfect and finished, given that the LifeWiki (as probably every alive wiki out there) is a never-ending work-in-progress made by volunteers/hobbyists? LifeWiki differs from Wikipedia in some ways, e.g. in specific notability guidelines, but as far as I can tell many other general guidelines carry over.

(This may be slightly off-topic here, but please do not remove external links even if they seem to be dead for a long time. One reason is that there are archival projects and the linked page may still be available in archived form. Another reason is that the linked website might become available later on another address. Preserving a dead link may later help someone else to fix it later. Removing a dead link just because it seems to be dead now may in practice mean that some knowledge is lost forever - even if the link is still preserved in the edit history, what's the chance that someone will actually find it there a few years later?)

[Book]

One more point on the value of raising such issues on this thread. The discussion of a claim which ensues on the forum, in which someone who knows stuff explains it and perhaps the source of it, even partially, sometimes is in and of itself a useful wiki reference.

[Book]

These assertions are from the wiki Density article:

1. The numbers in this sequence closely approximate the triangular number sequence.

(I assume this refers to max pop column)

does not seem to "closely approximate" to me.

2. For any side length of the form 3n-1, a segment of block agar can be used to reach a population of 4n². Up to n = 4 this is the optimal solution.

substantiation? resolved and noted in article 6/21/22

3. The density of a space dusty oscillator or spaceship is usually between 0.25 and 0.3.

substantiation?

4. The maximum average density of an oscillating agar is conjectured but not proven to be 1/2. The current upper bound is 8/13, proven by Hartmut Holzwart in 1992.

substantiation?

[hotdogPi]

These assertions are from the wiki Density article:
1. The numbers in this sequence closely approximate the triangular number sequence.
(I assume this refers to max pop column)
does not seem to "closely approximate" to me.

Code: Select all

0 4 8  16 18 28 36 43 54 64 76 90 104 119 136 152 171 190 210
3 6 10 15 21 28 36 45 55 66 78 90 105 120 136 153 171 190 210

As for #3, it's simply my personal observation.

[confocaloid]

I'd just like to state my own position on the "citation needed" tags, red links, and other (what I consider to be) consequences of the fact that the wiki is a work-in-progress. Specifically, I think there is no measurable harm in having these things left in articles and seen by readers for an indefinite period. I think that without having these lightweight and easy-to-use ways to specify intentions of editors, maintenance may become significantly harder. It seems much easier to delete a citation needed tag/a red link/ask for substantiation than to provide one. I do not think it is necessary to raise such issues individually - when there is no simple obvious solution and no obvious harm, it might be reasonable to leave things as they are.

A claim with a "citation needed" tag might be a simple lightweight way to preserve some knowledge while making it sufficiently clear that it may not be sufficiently well-sourced. I do not see an obvious immediate implication that such tags must be dealt with as soon as possible.

Similarly, a red link to a (currently) non-existent article may be a simple lightweight way to specify that that article is intended to be created later, or that it would be nice to have that article. Another useful consequence is that when there are links (red or not), it becomes possible to use the "What links here" tool to know contexts where a certain term or idea is mentioned/discussed, which may further help to understand how/if to write a dedicated article. Without red links, "What links here" does not work.

TL,DR: I think red links and "citation needed" tags may be useful in wiki.

[wwei47]

These assertions are from the wiki Density article:
1. The numbers in this sequence closely approximate the triangular number sequence.
(I assume this refers to max pop column)
does not seem to "closely approximate" to me.

Code: Select all

0 4 8  16 18 28 36 43 54 64 76 90 104 119 136 152 171 190 210
3 6 10 15 21 28 36 45 55 66 78 90 105 120 136 153 171 190 210

As for #3, it's simply my personal observation.

Well, is it really that surprising? Both sequences are O(n^2).

[Book]

As GUYTU6J has noted on the Tempest page: where did the name Tempest come from? Not in DRH's stamp collection nor mentioned searching any of the usual suspects. Note the recentness of this article's creation.

[dvgrn]

As GUYTU6J has noted on the Tempest page: where did the name Tempest come from? Not in DRH's stamp collection nor mentioned searching any of the usual suspects. Note the recentness of this article's creation.

Ahem. I'm embarrassed to admit that that was my fault -- calcyman picked up an injudicious naming suggestion of mine and put it into Catagolue.

I can usually resist trying to apply names to things, but I wanted to call that one "tempest", because there's a ship-shape in the middle of it getting tossed wildly around.

[Book]

As GUYTU6J has noted on the Tempest page: where did the name Tempest come from? Not in DRH's stamp collection nor mentioned searching any of the usual suspects. Note the recentness of this article's creation.

Ahem. I'm embarrassed to admit that that was my fault -- calcyman picked up an injudicious naming suggestion of mine and put it into Catagolue.

I can usually resist trying to apply names to things, but I wanted to call that one "tempest", because there's a ship-shape in the middle of it getting tossed wildly around.

So shall we move it to xp4_04qkc1qqz1606621? And let it seek its teapot (whatever that means)....

[hotdogPi]

So shall we move it to xp4_04qkc1qqz1606621? And let it seek its teapot (whatever that means)....

Keep it where it is. By now, it's an established name.

[Book]

This is from the F116 article:

After 116 ticks, it produces a Herschel at (32, 1) relative to the input. Its recovery time is 138 ticks; this can be reduced to 120 ticks by adding extra mechanisms to suppress the internal glider.

Can we substantiate the bold text?

[dvgrn]

This is from the F116 article:

After 116 ticks, it produces a Herschel at (32, 1) relative to the input. Its recovery time is 138 ticks; this can be reduced to 120 ticks by adding extra mechanisms to suppress the internal glider.

Can we substantiate the bold text?

Yeah, there's a 120-tick version possible by adding a galaxy, for example:

Code: Select all

x = 99, y = 55, rule = LifeHistory
C$.2C$2C16$50.C2.C$54.C$55.2C$49.C.2C6.C$49.C2.C3.C$48.C3.C.3C$47.C
11.C2.A$50.3C.C3.C3.3A$50.C3.C2.C7.A$47.C6.2C.C6.2A4.2B$29.B20.2C8.B
3.8B$28.3B21.C5.4B4.7B$28.2BC22.C2.C6B.9B$29.2B2C10.A13.6B.10B$30.2C.
B7.3A12.19B$31.4B5.A14.19B$32.4B4.2A13.17B$25.2A6.9B14.15B26.C$26.A7.
6B14.17B25.C.C$26.A.2A5.6B3.B2.2B2.22B23.C.C$27.A2.A4.19BD21B3.2B2.2B
12.C$28.2AB3.6BD13BDBD4B.24BC$29.9BDBD2B2A9B3D4B2.23BCBD$30.9B2D2B2A
11BD4B2.23B3CB$31.29B4.24BC$31.17B.4B10.24B$32.15B17.16B.B$32.15B17.
12B$33.13B5.A3.2A7.9B$35.13B2.A.A3.A6.11B5.2A$34.8B4.2A.A.A3.A8.7B.B
2A5.A$34.6B6.2ABA4.A11.4B2.BA.A.3A$34.5B8.B2.5A.A8.B2A2B5.A.A$34.B.B
5.2A.A.2A.A4.A.A8.2A7.2A$35.3B4.A.2A.A2.A.2A2.A$34.B2AB11.2A.A.2A$35.
2A!

Looks like it might be possible to cut that down a few more ticks with the correct sparker, but at p8 the minimum repeat time will be 120.

[Book]

Two unsubstantiated claims from the Fly-by deletion article:

1. The deletion of a pond appears to require a convoy which is 89 cells in width containing a very unusual p4 spaceship which has 273 cells.

2. There are small objects which have no known fly-by deletion reactions. (I know, tough to prove "no known" but still...)

[GUYTU6J]

Two unsubstantiated claims from the Fly-by deletion article...

I have linked to dvgrn's previous answer above.

---
This is a forums post rather than a LifeWiki statement, but I think it counts:

...
And a beautiful skew-symmetric constructible p33 also exists:

Code: Select all

x = 75, y = 75, rule = B3/S23
29bobo$28boo11bobo$27b3o13boo$29bo13b3o$43bo$29bo$29bo13bo$28bobo12bo$
29boo11bobo$29bo12boo$43bo$$26bo$25boo19bo$25bobo18boo$26bo18bobo$26bo
19bo$46bo$26bo$26b3o17bo$25b3o16b3o$45boo$46bobo3$54bo5boo$22bo31b3ob
ooboo$14boo38boo4bo11bo$13booboob4o32bo11bo4boo$3bo11bo4boo43booboob4o
$bboo4bo11bo45boo$b4obooboo63bo$8boo$bo8$73bo$65boo$o63booboob4o$7boo
45bo11bo4boo$4obooboo43boo4bo11bo$boo4bo11bo32b4obooboo$bbo11bo4boo38b
oo$12booboob3o31bo$13boo5bo3$26bobo$28boo$28b3o16b3o$28bo17b3o$48bo$
28bo$28bo19bo$27bobo18bo$27boo18bobo$28bo19boo$48bo$$31bo$31boo12bo$
30bobo11boo$31bo12bobo$31bo13bo$45bo$31bo$29b3o13bo$30boo13b3o$31bobo
11boo$43bobo!

A smaller variant of this can reflect gliders.

Can someone find this "smaller variant"? I am curious whether it is strictly volatile, and if yes, whether it is smaller than FractalFusion's solution.

[calcyman]

This is a forums post rather than a LifeWiki statement, but I think it counts:

A smaller variant of this can reflect gliders.

Can someone find this "smaller variant"? I am curious whether it is strictly volatile, and if yes, whether it is smaller than FractalFusion's solution.

It's this one, and it's far from strictly volatile (it's not even statorless).

Code: Select all

x = 51, y = 59, rule = B3/S23
4bo31b3o$3bobo32bo$3b2o32bo$3b2o$2b2o$2bo$2bo7bo$2b2o5bo$3b2o4bo3bo14b
2o$2b3o3b2o19b2o$3b2o4b2ob3o13bo$10bob2obobo$2o10bo2bob3o$3o9bo2bo4bo$
2o15bob3o$b2o13bo$2bo7bo6b4o3b2o$2bo6b4o6bo4bobo$b2o10bo10bo$2o6b3obo$
3o6bo4bo2bo$obo7b3obo2bo$bo10bobob2obo$15b3ob2o$20b2o3b2o6bo$16bo3bo4b
2o5b2o$20bo11bobo$19bo4$19bo$18bo$12b2o4bo3bo17b3o$12b2o3b2o21bo$18b2o
b3o17bo$19bob2obobo10bo$21bo2bob3o7bobo$21bo2bo4bo6b3o$26bob3o6b2o$25b
o10b2o$19bo6b4o6bo12b2o$18b4o6bo7bo11b2o$22bo13b2o12bo$17b3obo15b2o$
18bo4bo2bo9b3o$19b3obo2bo10b2o$21bobob2obo$24b3ob2o4b2o$29b2o3b3o$25bo
3bo4b2o$29bo5b2o$28bo7bo$36bo$35b2o$34b2o$34b2o$33bobo$34bo!