Talk:Dependent reflector
Revision as of 20:01, 4 July 2023 by Dvgrn (talk | contribs) (→"Dependent glider shuttle" proposal: signals, loops, and cycle length)
More periods
- p29 - https://conwaylife.com/forums/viewtopic.php?f=2&t=1177&p=8877&hilit=p29+dependent+reflector#p8860
- p37 - https://conwaylife.com/forums/viewtopic.php?p=145205#p145205
- p57 (or is it p114?) - https://conwaylife.com/forums/viewtopic.php?f=2&t=1437&p=148077&hilit=Dependent+reflector#p148077
- p94? - https://conwaylife.com/forums/viewtopic.php?f=2&t=3886&p=72957&hilit=Dependent+reflector#p72957 (may also be some other material to work with in that thread)
Chris857 (talk) 16:06, 3 July 2023 (UTC)
- I also saw https://conwaylife.com/forums/viewtopic.php?f=7&t=533&p=3682&hilit=reflector#p3625 which is a p59 reflector made of herschel tracks, which seems less interesting (and vary unwieldy) to include since the herschel spacing can be adjusted, so it seems less period dependent than the other examples here. Chris857 (talk) 20:08, 3 July 2023 (UTC)
"Dependent glider shuttle" proposal
Just to give my two cents here, "dependent reflector loop" seems to me like a much better name for this article than "dependent glider shuttle". Mainly this is because the patterns being referenced, p26 glider shuttle and p31 glider shuttle, are not actually shuttles and badly need to be renamed. Shuttles go back and forth, not round and round.
The first name was invented by codeholic back in 2014, and the second was just a copycat use of the same term by hotdogPi. Once those naming errors are repaired, it doesn't seem like there's going to be any reason to rename this article. These things really are loops made out of dependent reflectors, and that's a term that's been in use for a long time and is well recognized.
I'll probably give this a day to collect any other thoughts, then go ahead and rename those two non-glider-shuttles and patch up this article appropriately (unless I hear objections). Dvgrn (talk) 19:36, 3 July 2023 (UTC)
- The LifeWiki currently has articles for p60 glider shuttle, p71 glider shuttle, p165 glider shuttle, p49 glider shuttle, p42 glider shuttle, p50 glider shuttle, p26 glider shuttle, p31 glider shuttle, and p59 glider shuttle, and there's a p88 shuttle shown in the Shuttle article.
- The p60, p165, p42, p50, and p88 patterns really are shuttles. The p71, being a 180-degree dependent reflector, is maybe kind of an arguable case. But p49 and p59 just don't look right, any more than the p26 or p31 ones do -- those are clearly glider loops, not back-and-forth shuttles.
- The "p49 glider shuttle" doesn't even use dependent reflectors, so "p49 glider loop" would seem to be a much more appropriate name for that case. Dvgrn (talk) 20:36, 3 July 2023 (UTC)
- I'm the one who proposed the move, so here are my thoughts. The article describes oscillators that are made of dependent reflectors reflecting continuous streams of gliders. The glider streams are not signal streams, and the gliders are not signals, at least not with the "natural" interpretation where the information is encoded by presence or absence of a glider. Of course "dependent reflector" is an established useful term. However, as far as I know "dependent reflector loop" is a newly coined term, and I think it's confusing. I agree with forum posts that the gliders are not actually "looping" -- the dependent reflector does periodically produce new gliders as long as gliders come in, but a "hole" in the input stream doesn't become a "hole" in the output stream so the output stream is not really a continuation of the "loop". The oscillator does look like a loop geometrically, but I'm not sure the proposed term "dependent reflector loop" carries that meaning (without suggesting the wrong picture of a signal loop).
Personally, I like the alternative term "dependent glider shuttle", and (regarding other articles for existing oscillators of this type) I would prefer p26 glider shuttle and p31 glider shuttle to keep their current names. (Likewise for other oscillators of the same type that use dependent reflectors.) Confocal (talk) 20:55, 3 July 2023 (UTC)
- We might need a few tie-breaker opinions to sort this one out, then. I'm still thinking that the application of the word "shuttle" to things that go round and round and not back and forth, was a small mistake by codeholic back in 2014, that got duplicated a few times. It seems like it was a terminological accident, and it's not too late to correct it.
- I'm sympathetic to the idea of these things not being loops either -- at least, not signal loops. They're loops in the sense that a glider in spacetime location X allows (rather than directly causes) a glider to exist somewhat later in time in spacetime location Y ... and there's a chain of locations X, Y, Z, P, D, Q, etc. that lead right back around to X-plus-one-cycle again (after one full trip of the not-quite-signal around the not-exactly-loop). Instead of "glider at Y if and only if glider was at X", we have "glider at Y if glider was at X" but not the converse. Still seems pretty loopy to me. EDIT: Oops, that's not the converse, that's the inverse, right? "no glider at Y if no glider was at X (and no other differences)" is true for regular glider loops but not for these "dependent reflector loops".
- Agree that this can be transformed into an article about dependent reflectors, with the resulting oscillators shown as applications.
I think about a dependent reflector as a "source+sink" device that consumes an infinite glider stream and produces another infinite stream. It could be described as "a glider gun supported by a glider stream". So it is still possible to adjust the size (minimum population, bounding box) by moving parts. But it becomes impossible to say how many gliders are in the circuit. Similarly, one cannot tell how many ticks are needed for "one full trip". When there are no dependent reflectors in the closed chain, it is always possible to leave just one glider in the circuit, and divide the period of the resulting oscillator by the period of the original "fully packed" circuit to get the number of circulating gliders. With dependent reflectors that does not work.
If I had to invent a new term for such oscillators, maybe something with the word "chain" in it -- if there are "segments" of glider streams joined at ends, the whole oscillator becomes a "closed polygonal chain". But that's yet another new term.
For example forum search for "p26 glider shuttle" (link) gives a number of relevant results, so I'd prefer to keep the name as is, to follow existing usage. People were referring to that oscillator as "p26 glider shuttle" in discussions. Confocal (talk) 03:22, 4 July 2023 (UTC)
- Agree that this can be transformed into an article about dependent reflectors, with the resulting oscillators shown as applications.
- I'd be happy with a redirect from "p26 glider shuttle" to "p26 whatever we decide to call it instead" -- "p26 reflector chain" or whatever. But "p26 glider shuttle" doesn't really make any sense as a descriptive name, given the definition in the first section of shuttle. The second section was added relatively recently by Book, to try to make sense after the fact of the nonsensical use of "glider shuttle" that had crept in over the last decade.
- To me, using "shuttle" when you mean something that doesn't go back and forth like a weaver's shuttle is ... well, a fairly easy mistake to make, but basically just an obvious mistake, worth correcting as soon as it gets noticed. Why does "shuttle" seem like a good word to apply? -- especially in the case of the p49 glider shuttle? It seems like just plain the wrong word to be using.
- You won't find any use of "shuttle" to mean "something that lets lots of things travel around in a cyclical pattern" in, for example, the Life Lexicon. It's supposed to be just one active object traveling back and forth. Dvgrn (talk) 18:37, 4 July 2023 (UTC)
- Also, I don't think I agree with another statement a few paragraphs up:
But it becomes impossible to say how many gliders are in the circuit. Similarly, one cannot tell how many ticks are needed for "one full trip".
- It actually seems fairly straightforward in most cases to figure out how many active objects are making the rounds in one of these contraptions -- and, really, they can perfectly well still be called "signals", and it's not wrong to call one of these things a "loop", with the signals taking a well-defined amount of time (the "cycle length"?) going around the loop. There's nothing in the definition of signal that says that it has to be possible to remove the signal without damaging the circuit. Information is still flowing around the loop, it's just that the information for each glider is just the one-way implication that "there was an input glider in the right place N ticks ago because, well, I'm here now and the whole loop hasn't blown up yet".
- For example, there are eight signals in (what is currently called) the p31_glider_shuttle, cycling every 248 ticks. You can see them all in the phase shown below, though half the time one of them will be hidden in the dependent reflector. That's not really any different from a glider getting temporarily hidden in a Snark's reflection mechanism.
| cycle length of p31 dependent reflector loop (click above to open LifeViewer) |
The cycle length is the time it takes the white glider to travel from the pink marked location around the loop and back to the marked location again. If there are any cases where the number of signals or the cycle length can't be unambiguously defined, I'd like to see them. Dvgrn (talk) 20:01, 4 July 2023 (UTC)