Traffic light
| Traffic light | |||||||||
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| Pattern type | Constellation | ||||||||
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| Number of cells | 12 | ||||||||
| Bounding box | 9 × 9 | ||||||||
| Static symmetry | D8_1 | ||||||||
| Discovered by | JHC group | ||||||||
| Year of discovery | 1969 | ||||||||
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The traffic light is a common formation of four blinkers and is the most common member of the familiar fours, also being the only one made from oscillators. A common predecessor is the T-tetromino. Although it behaves in the same way in a number of Life-like rules as it does in Conway's Game of Life, it does not appear nearly as frequently in many of those rules (e.g. HighLife and Pedestrian Life) due to its common predecessors being unstable.[1]
Drawing a single cell in the middle of the traffic light while it is in its "+" phase will eat the whole traffic light, leaving nothing behind. Drawing a cell a knight's move away in the same ("+") phase results in a clean fishhook instead.
Approximately two thirds of blinkers are formed from traffic lights.
Two common evolutionary sequences that result in traffic lights are shown below. The one on the top, which is found in the intermediate stages of the bumper, takes 27 generations to complete, while the one on the bottom takes 28.
| (click above to open LifeViewer) RLE: here Plaintext: here |
Common formations that result in a traffic light are shown below. Patterns in the same row are in the same generation. To follow an evolutionary sequence, start from the bottom and move up; if there is nothing immediately above a pattern (even if there is something farther above), its evolutionary sequence converges with the closest column inward that has a pattern until they all reach the top. The two long sequences have sets of three dots, indicating skipped generations. Sparks that do not affect evolution are ignored.
| (click above to open LifeViewer) RLE: here Plaintext: here |
Traffic light hasslers
Similar to honey farm hasslers, a large number of traffic light hasslers have been discovered. A full list can be found at the traffic light hasslers page.
Partial traffic lights
After a traffic light is formed, or as it's being formed, some of its blinkers can be hit. Partial traffic lights can often be useful. Half and three quarters traffic lights require three gliders to form, although the 3G collision of two blinkers on opposite sides rather than adjacent is not via traffic light. Examples of formations and uses are below:
Two adjacent blinkers
- The first semi-natural p30 glider gun to appear in Catagolue was a queen bee shuttle with one side being capped normally with a block and the other side being half a traffic light plus D4 symmetrical support. It can be monomerised. (yl30_1_20, also works if the two halves are one cell closer)
Three blinkers
- An interchange is two groups of 3/4 traffic lights. Similarly, a U-turner generates a 3/4 traffic light plus a lone blinker and a block.
- The traffic stop relies on three out of four blinkers from a traffic light.
- The typical formation of twin hat involves a pi-heptomino hitting two opposite blinkers in the correct position and timing. As two opposite blinkers are rare, it usually forms from the centre blinker from the three out of four being hit and forming a pi-heptomino.
See also
References
- ↑ HighLife - An Interesting Variant of Life by David Bell (.zip file)
External links
- Traffic light at the Life Lexicon
- Traffic light at Adam P. Goucher's Catagolue (pseudo-object)
- 6 easily-constructible twelve-bit constellations at Mark D. Niemiec's Life Page (download pattern file: 12/12tl.rle)