Traffic light

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Traffic light
Pattern type Constellation
Number of cells 12
Bounding box 9 × 9
Period 2
Mod 2
Heat 16
Volatility 0.80
Strict volatility 0.80
Discovered by JHC group
Year of discovery 1969

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 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.

x = 7, y = 13, rule = B3/S23 2b2o$2bobo$5b2o9$2b4o$2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 8 THUMBSIZE 2 ]]
(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.

x = 194, y = 175, rule = B3/S23 112bo$112bo$112bo2$108b3o3b3o2$112bo$112bo$112bo3$111b3o2$109bo5bo$ 109bo5bo$109bo5bo2$111b3o4$112bo$111b3o$110bobobo$109b3ob3o$110bobobo$ 111b3o$112bo5$111b3o$110bo3bo$110bo3bo$110bo3bo$111b3o6$12bo9b2o88bo$ 11b3o7b2obo86b3o$10b5o5b2ob2o85b2ob2o$10bob2o6bob2o87b3o$11b2o8b2o89bo 6$12bo9b2o88bo$11bobo7bo2bo86bobo$10bo3bo5bo3bo85bo3bo$10bo2bo6bo2bo 87bobo$11b2o8b2o89bo6$22b2o$b3o7b3o7bo2bo16b3o67b3o77b3o$b3o7b3o6bob2o 17b3o67bobo77b3o$o2bo6bob2o6bob2o17b3o67b3o77bobo$b2o8bo9bo170bo6$22b 2o18bo69bo79bo$21bo2bo7bo9bo69bo69bo9bo$20bob2o7b3o8bo68bobo67b3o8bo$ 20bobo7bo3bo7bo69bo69bo8bobo$21bo20bo69bo79bo6$22b2o18bo69bo$21bo2bo 16bobo67bobo$20bo2bo157b3o$20bobo18bo69b3o66bobobo$21bo20b2o6$23bo$21b 2obo16b3o67b3o17b3o37b3o$21bobo17b3o67b3o17b2o38b2o$20bobo19bo69bo19b 2o38bo$21bo21bo129bo$43bo5$122bo39bo$52b2o58bo9bo7bo3bo17b2o8bo$51b2o 7b5o46b3o8bo8b3o17b2obo7bo7bobobo$62bo58bobo38b2o$53bo99bo4$130bo3bo$ 129bobobobo$82bo47b5o$82bo28bobo17b3o$71b3o6b2ob2o27bo19bo8bobobo24bob obo$72bo39bo$72bo4$130b2ob2o$93bo35bo5bo$82bo8bo2bo6bobo8bo17bo3bo$70b o3bo6bobo47b3o$91b3o7b3o7b3o27bobobo24bobobo$71b3o6b2ob2o5$72bo57b2ob 2o$72bo20bo36b2ob2o$71b3o17b3o16bobobo15b2ob2o$71b3o7b3o7b3o17b3o18bo$ 71b3o7bobo8bo19bo57bobobo$72bo7b2ob2o58bo$143bo$142bo$141bo$141b2o$93b 2o$71b3o36bo3bo$82bo9bo17bo3bo$70bo3bo7bo8b3o17b3o$71b3o7bobo87b2o$81b obo89b4o$81bobo5$72bo$71b3o$70bobobo$71bobo7$62bo$61bobo7b3o$60bo3bo5b o3bo$60bobobo5bo3bo$72bo8$70b5o$71b3o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 1 THUMBSIZE 2 ZOOM 4 WIDTH 800 HEIGHT 800 ]]
(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


External links