Eater 2
| Eater 2 | |||||||||
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| Pattern type | Strict still life Eater | ||||||||
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| Number of cells | 19 | ||||||||
| Bounding box | 7 × 7 | ||||||||
| Frequency class | 36.0 | ||||||||
| Discovered by | David Buckingham | ||||||||
| Year of discovery | Unknown | ||||||||
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Eater 2 (or block on hat siamese hat) is an eater that was found by David Buckingham in the 1970s.[1] Mostly it works like the standard eater (see eater 1) but with two slight differences that make it useful despite its size; it takes longer to recover from each bite and it acts like an eater in two directions. The first property means that, among other things, it can eat a glider in a position that would destroy an eater 1 due to the latter recovering too quickly before all of the sparks have cleared. This novel glider-eating action is occasionally of use in itself, and combined with the symmetry means that an eater 2 can eat gliders along four different paths.
An eater 2 variant noticed by Stephen Silver in May 1998 that is useful for obtaining smaller bounding boxes is shown below. Note that the canonical version of eater 2 and the second to fourth variants below are strict still lifes because the outside 15-cell component is not stable without the block (it is, rather, an inductee), while the latter has a table (which isn't stable by own), but the first eater 2 variant below is pseudo still life (because the it is comprised of an aircraft carrier, block and hat, each of which are stable).
| Eater 2 variant (aircraft carrier, block and hat) (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here |
| Eater 2 variant (table, block and hat) (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here |
| Eater 2 variant (systematically named 'block on hat siamese shillelagh', higher clearance than the other two) (click above to open LifeViewer) Catagolue: here |
| Edgy eater 2 variant ( even higher clearance than other two and can perform a block catalysis in addition to a eater catalysis, although it can only perform an eater catalysis from one side due to its lack of symmetry. ) (click above to open LifeViewer) Catagolue: here |
| Eater 2 can eat gliders along four paths (click above to open LifeViewer) RLE: here Plaintext: here |
Eater 2 can also be used to eat objects other than gliders. For example, one of them can eat a lightweight or middleweight spaceship, two of them can eat a 60P5H2V0, and so on. Eater 2 catalysts can be found in many stable conduits such as RNE-19T84 and boojum reflector. Its symmetry is exploited in 35P12.1 and p196 pi-heptomino hassler.
A picture of eater 2 serves as the logo of Catagolue.
Glider synthesis
On January 29, 2004 Mark Niemiec found a 9-glider synthesis of a variation of eater 2 that consists of a hat, a block, and a table shown above. On October 9th, 2014, David S. Miller found a natural eater 2 in a soup from Adam P. Goucher's apgsearch script[2], from which Tanner Jacobi derived a 6-glider synthesis.[3] Another 6-glider recipe with moderate clearance and better adjustability was found by gmc_nxtman on July 14, 2017, involving a boat, a pi-heptomino and a teardrop.[4]
Occurrence
- See also: List of common still lifes
The canonical eater 2 ranks 381st out of 45,759 in the list of 19-cell still lifes. This puts it barely in the top 1%.
See also
- Tablecloth
- Eater 3
- Eater 4
- Eater 5
- Period-44 MWSS gun
- Buckingham's p13
- 134P39.1 (LCM, uses a p3 variant of eater 2)
- 90P51 (Same as 134P39.1)
- 72P68 (LCM, uses a p4 variant of eater 2)
- 74P85 (LCM, uses a p5 variant of eater 2)
References
- ↑ Dean Hickerson's oscillator stamp collection. Retrieved on March 14, 2020.
- ↑ David S. Miller (October 10, 2014). Re: apgsearch: a high-performance soup searcher (discussion thread) at the ConwayLife.com forums
- ↑ Tanner Jacobi (November 8, 2014). Re: Soup search results (discussion thread) at the ConwayLife.com forums
- ↑ gmc_nxtman (July 14, 2017). Re: Thread for your unsure discoveries (discussion thread) at the ConwayLife.com forums
External links
- Eater 2 at the Life Lexicon
- Eater 2 at Adam P. Goucher's Catagolue
- Nineteen-Bit Life Objects at Mark D. Niemiec's Life Page
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- Patterns
- Patterns with Catagolue frequency class 36
- Natural periodic objects
- Periodic objects with minimum population 19
- Patterns with 19 cells
- Patterns found by David Buckingham
- Patterns that can be constructed with 6 gliders
- Still lifes
- Strict still lifes
- Strict still lifes with 19 cells
- Eaters
- Patterns with bilateral diagonal symmetry
- Catalysts