On 21 March 2004 3:59pm, dvgrn wrote:Subject: Grabbers, shovers, and highway robbers
Recently I've been trying to put together a special-purpose glider reflector that can reflect a glider on a given glider lane, but let gliders on neighboring lanes get past -- in the minimal case, the separation between lanes might be just a single cell (orthogonally, not diagonally).
The only way I know how to do this is to set up a grazing shot with some small still life, and then duplicate the resulting signal and set up an appropriate collision to rebuild the still life. Not too difficult, but there are so many possible designs that it's hard to figure out which way is best.
So I looked for a "bait" still life that could be dangled at the edge of the glider lane, and which would produce a tameable signal after a grazing shot. It also needed to be rebuildable with a minimum number of synchronized signals.
In the process, I ran into an interesting catalysis by a boat -- anyone know if it's been seen before?
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.oo......
o.o......
.o.......
.........
.........
.........
......oo.
.....o..o
.....o.o.
......o..
.........
.........
.........
.....ooo.
.....o...
......o..
There was also a nice glider-plus-boat -> two-gliders converter, though it wasn't quite what I wanted in this case. Probably already known, or generally useless, or both...
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.oo.......
o.o.......
.o........
..........
..........
......oo..
ooo...o...
o......ooo
.o.......o
This beehive -> LOM conversion might possibly be useful, but I haven't figured out how to reduce the amount of junk it leaves behind:
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.o....................
o.o...................
o.o...............oo..
.o................o...
...................ooo
..............oo.....o
..............oo......
ooo...................
o.....................
.o....................
Paul Chapman's Glue project has turned up a few patterns that are extremely good at this kind of sneaky glider-highway robbery [to mix my fishing and criminal metaphors unforgivably.]
For example, this pattern grabs a glider from the edge of the highway without disturbing a second glider following at the minimum distance:
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.oo....
o.o....
.o.....
.......
.o.....
o.o....
o.o....
.o.....
.......
.......
.......
ooo....
o......
.o.....
....oo.
....o.o
....o..
This one works with a following distance of 16:
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.oo.....
o..o....
.oo...o.
.....o.o
......o.
........
........
.ooo....
.o......
..o.....
........
.....ooo
.....o..
......o.
But these are both relatively expensive to reconstruct, I think.
This simple two-beehive constellation throws a glider in the other direction -- it's a "shover" instead of a "grabber". Having the glider cross the highway ruins the following-distance rating, of course, but I didn't really need it anyway:
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.oo.............
o..o....oo...ooo
.oo....o..o..o..
........oo....o.
If that's not enough, this one throws _two_ gliders across the highway, and is even easier to rebuild:
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.oo...ooo
o..o..o..
.oo....o.
.........
.........
.........
.........
.........
.........
.........
....oo...
....oo...
All of these constellations take nine or ten slow gliders to rebuild, starting from a single block. And since there's no single block left over after the glider-turning reactions, the Glue recipe doesn't seem like an efficient way to rebuild the bait.
Also the slow gliders would all come in along the highway, in the same direction as the input glider -- so most of them would have to be put in with glider inserters of one kind or another.
------------------------------
After some experimentation I settled on this reaction for Round One:
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x = 31, y = 59, rule = B3/S23
28bo$28bobo$28boo7$12bo$10boo$11boo$3bo$b3o$o$oo18$12bo$11boo$11bobo
21$27boo$27bobo$27bo!
Loaves take three gliders to rebuild, but only one glider to make from a blinker -- and a blinker can be made with two gliders in a couple of ways. So at least all three don't have to be simultaneously synchronized.
Because I've been working on a lot of slow-salvo-constructible Herschel circuitry in the last few months, my first-draft sample uses only well-separated small still lifes. Here's the first thing I could get Hersrch to give me -- it's just blocks and eaters, in fact, plus five beehives, a boat, a tub, and a loaf.
It looks positively primeval, since all the pieces are several years old -- most of them are borrowed from Paul Callahan's constructions, from back before Herschel conduits with eater2's and custom eaters had come into common use:
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#C Highway robber: snags a glider travelling at the edge of a
#C 'glider highway' and reflects it or produces an output Herschel;
#C no effect on (most) other gliders travelling in the highway.
x = 395, y = 366, rule = B3/S23
304bo$304b3o$307bo23boo$306boo23bo$329bobo$287bo37boobboo$287b3o35boo$
290bo$273boo14boo11boo$273boo27boo3$267boo$267boo$271boo$271boo$$331b
oo$313boo16bobo$266boo44bobo18bo$266boo44bo20boo$311boo4boo$316bobo$
316bo$303boo10boo7boo$303bobo18boo$305bo$305boo4$273boo$274bo59boo$
271b3o60bo$271bo60bobo$286boo44boo$286bobo28bo$288bo28b3o$288boo30bo$
319boo5$341bo9bo$278boo61b3o5b3o$269boo7boo64bo3bo13boo$270bo72boo3boo
13bo$270bobo89bo$271boo89boo$312boo$312boo79bo$289boo101bobo$289bo102b
obo$287bobo103bo$287boo28boo46boo$317boo46boo$313boo$273boo38boo$272bo
bo$272bo$271boo46boo$319boo13boo$333bobo11boo6bo$333bo13boo6b3o$332boo
24bo$357boo$$276boo$277bo$274b3o$274bo4$292boo$292bobo$294bo$294boo4$
265bo$263b3o$239bo22bo$227bo11b3o20boo20boo$225b3o14bo32boo7boo$209bo
14bo16boo33bo$209b3o12boo50bobo$212bo58boo4boo$211boo59bo20boo$272bobo
18bo$273boo16bobo$212boo77boo$212boo17boo$231boo6$228boo32boo$228bo20b
oo11boo$164bo64b3o18bo$162b3o66bo15b3o35boo$136boo23bo63boo20bo37boobb
oo$137bo23boo62bo63bobo$137bobo86b3o62bo$138boobboo37bo46bo62boo$142b
oo35b3o15bo9bo$178bo18b3o5b3o$165boo11boo20bo3bo$165boo32boo3boo$$234b
oo$234bo$215boo15bobo$215boo15boo3$136boo52boo$135bobo16boo34boo$135bo
18bobo45boo$134boo20bo44bobbo95bo$150boo4boo44boo4boo90b3o$150bobo55bo
bo92bo$152bo57bo91boo$143boo7boo56boo105boo$143boo20boo33boo115bo$166b
o34bo12boo99bobo$163b3o32b3o12bobo88bo10boo$163bo34bo14bo89bobo$212boo
89bobo$193boo103boo4bo$193bo103bobo15boo$133boo59b3o100bo17bobo$134bo
61bo99boo19bo$134bobo180boo$135boo154boo$292bo$292bobo$224boo67boo$
224boo$153boo151boo$153bo152boo$151bobo$151boo$$213boo$214bo19boo$214b
obo17bo$215boo15bobo$227bo4boo$226bobo89boo$226bobo89bo$215boo10bo88bo
bo$214bobo99boo$214bo$133boo15boo61boo$132bobo15boo76boo$132bo95bo$
131boo96b3o$231bo3$19boo$12boo5boo$12boo124bo86bo$48boo88b3o82b3o72boo
15boo$48bo92bo80bo74bobo15boo$14boo17boo14bo11bo57boo19boo80boo73bo25b
oo$14boo17bo14boo9b3o57bo15bo160boo25bo$8boo21bobo24bo58bobo15b3o183bo
bo$8boo21boo25boo10boo45boo19bo102bo79boo$70bo19boo45boo102b3o$68bobo
18bobo152bo$68boo19bo153boo$45boo41boo138boo73bo$45boo181boo73b3o$306b
o$134boo98boo48bo20boo$134boo17boo79bo47b3o15bo$113boo38boo77bobo46bo
18b3o$85boo26boo117boo34boo11boo20bo$85boo181boo32boo$35boo117boo$5boo
28bo18boo98bo$6bo29b3o16bo85boo12b3o$6bobo29bo13b3o69boo16bo14bo$7boo
43bo71bo14b3o$115boo8b3o11bo159boo$75boo38bobo9bo79boo90boo17boo$75bo
41bo90bo34boo73boo$76b3o11boo25boo86b3o35boo11boo$78bo11boo113bo50bo$
257b3o59boo$215boo42bo59bo$104boo109boo89boo12b3o$104bo134boo66bo14bo$
105b3o131bo64b3o$107bo132b3o25boo34bo$8boo84boo146bo26bo$8boo14boo69bo
170b3o$oo22bo67b3o171bo$bo23b3o64bo$bobo23bo$bboo216boo$221bo$218b3o$
218bo$21bo$19b3o$18bo$18boo$24bo74boo$22b3o74boo5boo$21bo84boo$21boo
50bo$71b3o$70bo14boo17boo$70boo14bo17boo$86bobo21boo$87boo21boo220boo$
24boo306boo$5boo17boo311bo$5boo38boo288b3o$45boo26boo259bo$73boo259boo
$4boo306boo$5bo306boo$bb3o12boo$bbo14bo$18b3o$20bo22boo$42bobo38boo29b
o$42bo41bo27b3o209boo$41boo25boo11b3o27bo212boo$68boo11bo29boo225boo$
338boo$342boo$54boo60boo224boo$55bo60boo$52b3o$52bo$64boo60boo$64bo61b
o$65b3o56bobo$67bo56boo$87boo$86bobo$86bo$85boo$$97boo$97boo219boo$
318bobo$319bo5$102boo$101bobo$101bo214boo$100boo213bobo$315bo$314boo7b
oo$323boo6$334bo$332b3o$331bo$331boo6$313boo$242boo70bo$243bo70bobo$
243bobo69boo$244boo3$236boo48bo$221boo13bo47b3o15bo$221boo11bobo46bo
18b3o6boo$234boo34boo11boo20bo6bo$135bo53bo80boo32boo6bobo$133b3o53b3o
121boo$132bo59bo$132boo57boo21boo$204bo9boo110boo$202b3o121bobo$201bo
99boo25bo$201boo98boo25boo$245boo$148boo95boo11boo$149bo25bo11boo69bo$
149bobo21b3o11boo25boo43b3o$66bo83boo20bo41bo46bo62boo$64b3o105boo38bo
bo93boo14bo$63bo148boo27boo48boo16bo15b3o$63boo176bo49bo14b3o6bo11bo$
242b3o25boo20b3o11bo7bobo$145bo98bo26bo22bo20bo$143b3o122b3o$142bo125b
o$142boo38boo$182boo26boo13boo$210boo13boo3boo$230boo$65boo39bo$64bobb
o38b3o$64bobo42bo121boo$65bo42boo41boo32boo38boo4bo$151boo11boo20bo38b
oo5b3o$164bo18b3o48bo$165b3o15bo$167bo$$139boo6boo$139bo7bo$140b3o5b3o
$103boo37bo7bo$103boo$$93bo$93b3o35boo$96bo34boo3boo$95boo39boo3$137b
oo$131boo4bo$131boo5b3o$140bo$$120boo$120bobo$122bo$122boo$$116boo$
116boo7$110boo$110bo$111b3o$113bo$99b3o$99bo$100bo$103b3o$103bo$104bo!
Obviously this is nowhere near optimal -- it takes over 3000 generations to recover. Basically I just wanted to get something working without getting bitten too badly by the combinatorial dragons that lurk in these parts. As usual, the Herschel-circuit connections are thanks to Hersrch.
Somebody must have an idea for at least a factor-of-two improvement on this...
Keep the cheer,
Dave Greene
