Pentadecathlon
Pentadecathlon | |||||||||||
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Pattern type | Oscillator | ||||||||||
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Number of cells | 12 | ||||||||||
Bounding box | 16×9 | ||||||||||
Frequency class | 18.6 | ||||||||||
Period | 15 | ||||||||||
Mod | 15 | ||||||||||
Heat | 22.4 | ||||||||||
Volatility | 1.00 | ||||||||||
Strict volatility | 1.00 | ||||||||||
Discovered by | John Conway | ||||||||||
Year of discovery | 1970 | ||||||||||
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Pentadecathlon (or PD; plural pentadecathlons[note 1]) is a period-15 oscillator that was found in 1970 by John Conway[2] while tracking the history of short rows of cells (see one-cell-thick pattern); indeed, an orthogonal row of 10 cells evolves into this object. It is the only known oscillator that is a polyomino in more than one phase (besides the blinker).
Commonness
Pentadecathlon is the most natural oscillator of period greater than 3 (and indeed, the second most natural oscillator of period greater than 2) in Achim Flammenkamp's census. In fact, it is the fifth or sixth most common oscillator overall in this census, being about as frequent as the clock, but much less frequent than the blinker, toad, beacon or pulsar.[3][4] It is also the most common oscillator with a volatility of 1. The pentadecathlon is also the fifty-second most common object on Adam P. Goucher's Catagolue and by far the most common period 15 oscillator, with all other natural oscillators of that period featuring it combined with some other object.[5]
The second-most common period-15 oscillator, bi-pentadecathlon 1, consists of two pentadecathlons placed next to each other so that their sparks cancel out. This oscillator first appeared naturally in March 2015,[6] and the reaction which produced it later led to a 7-glider synthesis of a bi-pentadecathlon.[7] Additionally, a pulsar-on-pentadecathlon is the largest object to have occurred in the B3/S23/C1 census as of September 2020, with 100 cells in its maximum phase.[8][5]
Uses of the pentadecathlon
The pentadecathlon is so called because it has a period of 15 generations. This, being a factor of 30, means that it can be elegantly used in combination with period 30 devices (based on the queen bee shuttle). Firstly, it can reflect a glider 180° as in p60 glider shuttle, and a pair of perpendicular pentadecathlons can rotate a glider 90°.
Hassling capabilities
The pentadecathlon is classified as a pulsating oscillator, since it undulates throughout its cycle. During this process, the pentadecathlon throws off multiple accessible sparks. More specifically, the oscillator produces horizontal T-nose sparks, horizontal V sparks and vertical domino sparks. Two copies of these domino sparks can be used to hassle toads in two distinct ways. The V sparks elegantly convert blocks into gliders, which forms the basis of the p30 *WSS => glider converter and aforementioned glider reflectors. This property is also exploited in numerous oscillators.
Hassling an object in the butterfly sequence; p15 (click above to open LifeViewer) |
Hassling a toad (toadsucker); p60 (click above to open LifeViewer) |
Synthesis
On April 11, 1997, Heinrich Koenig found a three-glider collision that produced a clean pentadecathlon. This was a surprising result at the time. Four-glider pentadecathlon recipes had been known and used for many years, so this was an unlooked-for improvement, very similar to Luka Okanishi's discovery of a three-glider synthesis of a switch engine almost twenty years later. This also makes the pentadecathlon the rarest object in Catagolue for which a 3-glider synthesis is known.
Other rules
See also
- Jolson
- Karel's p15
- Loaflipflop
- Mold on pentadecathlon
- Pentadecathlon on 37P7.1
- Pentadecathlon on thumb 1
- PD-pair reflector
Notes
References
- ↑ "ἆθλον". English Wiktionary. Retrieved on 2016-06-16.
- ↑ Dean Hickerson's oscillator stamp collection. Retrieved on March 14, 2020.
- ↑ Achim Flammenkamp (September 7, 2004). "Most seen natural occurring ash objects in Game of Life". Retrieved on January 15, 2009.
- ↑ "Census Results in Conway's Game of Life". The Online Life-Like CA Soup Search. Retrieved on July 12, 2009.
- ↑ 5.0 5.1 Adam P. Goucher. "Statistics". Catagolue. Retrieved on September 22, 2020.
- ↑ gameoflifeboy (March 8, 2015). Re: Soup search results (discussion thread) at the ConwayLife.com forums
- ↑ gmc_nxtman (October 29, 2015). Re: Soup search results (discussion thread) at the ConwayLife.com forums
- ↑ gameoflifeboy (April 20, 2015). Re: Soup search results (discussion thread) at the ConwayLife.com forums
External links
- Pentadecathlon at the Life Lexicon
- 12P15.1 at Heinrich Koenig's Game of Life Object Catalogs
- Patterns
- Patterns with Catagolue frequency class 18.6
- Natural periodic objects
- Oscillators with 12 cells
- Patterns with 12 cells
- Patterns found by John Conway
- Patterns found in 1970
- Patterns that can be constructed with 3 gliders
- Oscillators
- Periodic objects with minimum population 12
- Oscillators with period 15
- Oscillators with mod 15
- Oscillators with heat 22
- Oscillators with volatility 1.00
- Oscillators with strict volatility 1.00
- Patterns with rectangular orthogonal symmetry
- Sparkers
- Sparkers with period 15
- Domino sparkers
- Strong sparkers
- Weak sparkers