Snark

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Snark
14b2o$14bobo$16bo4b2o$12b4ob2o2bo2bo$12bo2bobobobob2o$15bobobobo$16b2o bobo$20bo2$6b2o$7bo7b2o$7bobo5b2o$8b2o7$18b2o$18bo$19b3o$21bo7$3o$2bo$ bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ WIDTH 600 HEIGHT 600 X 4 Y -4 THUMBSIZE 3 ZOOM 21 GPS 30 LOOP 128 ]]
Pattern type Stable reflector
Number of cells 52
Bounding box 23 × 17
Angle 90°
Repeat time 43
Discovered by Mike Playle
Year of discovery 2013

The Snark is a 90° stable glider reflector discovered by Mike Playle on April 25, 2013.[1] It is made up of two eater 1s, a block and a 31.4, the "heart" of the Snark. It is currently the fastest and the smallest 90° stable glider reflector, both in terms of the population and the bounding box. Another commonly-used stabilization of the catalyst has 34 bits, and many other variants are available. For an example of a color-changing reflector, see the stable reflector article, or see bouncer for small periodic options.

#C four Snark catalyst variants #C Top: original variant by Mike Playle #C Left: Shannon Omick (better clearance on a diagonal) #C Right: Heinrich Koenig (better clearance on a different diagonal) #C Bottom: Simon Ekström (better clearance on two diagonals) x = 51, y = 52, rule = B3/S23 20b2o$20bobo$22bo4b2o$18b4ob2o2bo2bo$18bo2bobobobob2o$21bobobobo$22b2o bobo$26bo2$12b2o$13bo7b2o$13bobo5b2o$14b2o25bo$39b3o$38bo$38b2o3$46b2o $24b2o21bo$24bo22bob2o$14b3o8b3o11b2o4b3o2bo$4bo11bo10bo11b2o3bo3b2o$ 2b5o8bo5b2o21b4o$bo5bo13bo8b2o15bo$bo2b3o12bobo7bobo12b3o$2obo15b2o8bo 13bo$o2b4o21b2o14b5o$b2o3bo3b2o11bo22bo2bo$3b3o4b2o11b3o22b2o$3bo22bo$ 2obo21b2o$2ob2o3$11b2o$12bo$9b3o$9bo25b2o$28b2o5bobo$28b2o7bo$37b2o2$ 24bo$23bobob2o4b2o$23bobobobo2bo2bo$22b2obobobo3b2o$23bo2b2ob4o$23bo4b o3bo$24b3obo2bo$26bobobo$29bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBLAUNCH THUMBSIZE 2 ZOOM 8 HEIGHT 480 THEME Book GRID GRIDMAJOR 0 STARTFROM 232 ]]
Four Snark catalyst variants:
top: Mike Playle (original variant, works under the rulespace of B3/S23 - B34c8/S234c5e6n8); left: Shannon Omick (better clearance on a diagonal); right: Heinrich Koenig (better clearance on a different diagonal); bottom: Simon Ekström (better clearance on two diagonals).
The last 3 variants also work in more rules, with the transition B4q.
(click above to open LifeViewer)
RLE: here Plaintext: here
Catagoluehere

While the repeat time is 43, a continuous period-38 stream triples the period to 114, while a continuous period-41 stream quadruples the period to 164. A period-42 stream creates an extraneous honey farm, which can be deleted with a block, doubling the period to 84; this was used in a previous version of the smallest period-84 glider gun.

History

The base reaction was discovered by Dietrich Leithner about 1998, but while it successfully restored one block catalyst, it consumed another block.[2] Some attempts were made to restore the missing block using periodic sparkers; the p4 reflector is an example.

In the 1990s, two $100 bounties had been offered for the discovery of a small stable reflector that fit inside a 50x50 bounding box. The boojum reflector and rectifier, both 180-degree reflectors, were found in 2001 and 2009, so revised bounties specified 90-degree reflection and the same 50x50 bounding box, or 35x35 for a doubled bounty. A 90-degree "Snark" reflector matching those criteria remained elusive until 2013.

A catalyst that could restore the missing block in Leithner's reaction was found with Bellman, a program for searching catalytic reactions developed by Mike Playle. Given its small repeat time, the new Snark enabled adjustable glider loop oscillators of previously unknown periods of 43 and 53 to be constructed.[3] It also made most large symmetrical Herschel loop guns obsolete, since it is now possible to make use of the Herschel gliders with a shorter path of the Herschel track itself.[4]

The Snark was voted Pattern of the Year for 2013 in a belated vote held on the ConwayLife.com forums.[5]

Etymology

Like several other terms including Bandersnatch and Jubjub, the term "Snark" (and the common capitalization of these names) is taken from Lewis Carroll's poem The Hunting of the Snark, where mysterious creatures called "Snarks" were much sought after. Snarks came in more than one form -- some had feathers, some had whiskers, etc. -- and one form was dangerous and best avoided.

The name "boojum reflector", given to the first small stable 180-degree reflector, was intended to convey the idea that in a Conway's Life context, "Snarks" were small stable reflectors in general -- and that the 180-degree subcategory was the much less desirable type of Snark. By implication, then, "common Snarks" were the useful 90-degree category. Thus, up until 2013, "Snark" was occasionally used to refer to a hypothetical small 90-degree stable reflector, as yet undiscovered. Playle's search program was written specifically with stable-reflector searches in mind, and the name "Bellman" is borrowed from the leader of the Snark-hunting expedition in Carroll's poem.

The pre-2013 sense of the term "Snark" is still used occasionally, as a way to refer to any small 90-degree stable reflector, not necessarily "the" Snark discovered by Playle or its variants. In such cases an adjective usually accompanies the word "Snark", to make it clear that the reference is to (for example) a hypothetical color-changing Snark or Spartan Snark, rather than to the standard Snark which is color-preserving and non-Spartan.[6]

In other rules

Under B4z, the 31.4 recovers 1 generation faster for the first two catalysts shown in the Snark variants infobox (the other two catalyst versions in the above pattern fail, though larger stabilizations are possible), though the Snark still has RT=43 due to sparks.

See also

References

  1. Mike Playle (April 25, 2013). Just the place for a Snark! (discussion thread) at the ConwayLife.com forums
  2. Adam P. Goucher (February 17, 2010). Re: Incomplete search patterns - try to complete (discussion thread) at the ConwayLife.com forums
  3. Matthias Merzenich (April 25, 2013). Re: Just the place for a Snark! (discussion thread) at the ConwayLife.com forums
  4. Dave Greene (May 4, 2013). Re: Just the place for a Snark! (discussion thread) at the ConwayLife.com forums
  5. 77topaz (March 29, 2018). Re: Belated Pattern of the Year 2013 competition: Voting (discussion thread) at the ConwayLife.com forums
  6. Dave Greene (November 8, 2024). Re: Thread for your basic questions (discussion thread) at the ConwayLife.com forums

External links