Eater 2

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Eater 2
x = 7, y = 7, rule = B3/S23 3bob2o$b3ob2o$o$b3ob2o$3bobo$3bobo$4bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 ZOOM 21 HEIGHT 400 SUPPRESS ]] [[ ZOOM 39 ]]
Pattern type Strict still life
Eater
Number of cells 19
Bounding box 7 × 7
Frequency class 36.0
Discovered by David Buckingham
Year of discovery Unknown

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).

x = 6, y = 9, rule = B3/S23 2o$o$2bob2o$b2ob2o2$b2ob2o$2bobo$2bobo$3bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]]
Eater 2 variant (aircraft carrier, block and hat)
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RLE: here Plaintext: here
Catagoluehere
x = 7, y = 7, rule = B3/S23 o2bob2o$4ob2o2$2b2ob2o$3bobo$3bobo$4bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]]
Eater 2 variant (table, block and hat)
(click above to open LifeViewer)
RLE: here Plaintext: here
Catagoluehere
x = 6, y = 8, rule = B3/S23 2o$obob2o$2bob2o$bo$b2ob2o$2bobo$2bobo$3bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]]
Eater 2 variant (systematically named 'block on hat siamese shillelagh', higher clearance than the other two)
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Catagoluehere
x = 7, y = 8, rule = B3/S23 3b2o$3b2o2$b3obo$o3b2o$b2o$3b2obo$3bob2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]]
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)
Catagoluehere
x = 21, y = 22, rule = B3/S23 18bo$18bobo$18b2o3$16bo$16bobo$16b2o$11bo$11bobo$11b2o2$8bo$8bobo$8b2o $3bob2o$b3ob2o$o$b3ob2o$3bobo$3bobo$4bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]]
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

References

  1. Dean Hickerson's oscillator stamp collection. Retrieved on March 14, 2020.
  2. David S. Miller (October 10, 2014). Re: apgsearch: a high-performance soup searcher (discussion thread) at the ConwayLife.com forums
  3. Tanner Jacobi (November 8, 2014). Re: Soup search results (discussion thread) at the ConwayLife.com forums
  4. gmc_nxtman (July 14, 2017). Re: Thread for your unsure discoveries (discussion thread) at the ConwayLife.com forums

External links