Boojum reflector: Difference between revisions
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The '''boojum reflector''' is a 180° [[glider]] [[reflector]] found by [[Dave Greene]] in April {{year|2001}}, winning $100 bounties offered by [[Alan Hensel]] and [[Dieter Leithner]]. The name is taken from Lewis Carroll's ''The Hunting of the Snark'', referring to the fact that a small 90-degree stable reflector was really what was wanted.{{refn|group=note|180-degree reflectors are relatively undesirable and have limited use in larger circuitry constructions because they cannot get a glider to wherever it needs to be.}} | The '''boojum reflector''' is a 180° [[glider]] [[reflector]] found by [[Dave Greene]] in April {{year|2001}} as a modification of [[Herschel receiver|Paul Callahan's Herschel receiver]],<ref>{{LinkForumThread | format = ref | title = Re: History Of ConwayLife | p = 115054 | author = dvgrn | date = December 9, 2020 }}</ref> winning $100 bounties offered by [[Alan Hensel]] and [[Dieter Leithner]]. The name is taken from Lewis Carroll's ''The Hunting of the Snark'', referring to the fact that a small 90-degree stable reflector was really what was wanted.{{refn|group=note|180-degree reflectors are relatively undesirable and have limited use in larger circuitry constructions because they cannot get a glider to wherever it needs to be.}} | ||
The boojum reflector was both the smallest and fastest known [[stable reflector]], until it was superceded by the [[rectifier]] in {{year|2009}} and the [[Snark]] in {{year|2013}}. | The boojum reflector was both the smallest and fastest known [[stable reflector]], until it was superceded by the [[rectifier]] in {{year|2009}} and the [[Snark]] in {{year|2013}}. | ||
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==External links== | ==External links== | ||
{{LinkLexicon|lex_b.htm#boojumreflector}} | {{LinkLexicon|lex_b.htm#boojumreflector}} | ||
==References== | |||
<references /> | |||
Revision as of 01:46, 15 December 2020
| Boojum reflector | |||||||||
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| Pattern type | Stable reflector | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Number of cells | 60 | ||||||||
| Bounding box | 44 × 32 | ||||||||
| Angle | 180° | ||||||||
| Repeat time | 202 | ||||||||
| Discovered by | Dave Greene | ||||||||
| Year of discovery | 2001 | ||||||||
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The boojum reflector is a 180° glider reflector found by Dave Greene in April 2001 as a modification of Paul Callahan's Herschel receiver,[1] winning $100 bounties offered by Alan Hensel and Dieter Leithner. The name is taken from Lewis Carroll's The Hunting of the Snark, referring to the fact that a small 90-degree stable reflector was really what was wanted.[note 1]
The boojum reflector was both the smallest and fastest known stable reflector, until it was superceded by the rectifier in 2009 and the Snark in 2013.
The boojum reflector produces an unwanted beehive, which is then deleted by a later glider. If the beehive is removed before the latter glider hits it, the glider will leave the reflector. This reaction can be seen in this p226 glider shuttle:
| (click above to open LifeViewer) RLE: here Plaintext: here |
A different type of Boojum shuttle is possible by switching the output gliders and the beehive deleting gliders. The corresponding beehive-glider collision does not become nothing by itself, so a catalyst is required to delete it, but the block from that boojum suffices.
| (click above to open LifeViewer) RLE: here Plaintext: here |
Notes
- ↑ 180-degree reflectors are relatively undesirable and have limited use in larger circuitry constructions because they cannot get a glider to wherever it needs to be.
External links
- Boojum reflector at the Life Lexicon
References
- ↑ dvgrn (December 9, 2020). Re: History Of ConwayLife (discussion thread) at the ConwayLife.com forums