Interchange

Interchange
2b3o4b3o2b2$o12bo$o12bo$o12bo2$2b3o4b3o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 450 THUMBSIZE 3 ZOOM 30 GPS 2 LOOP 2 ]]
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Pattern type	Constellation
Number of cells	18
Bounding box	16 × 9
Static symmetry	D4_+2
Discovered by	Hugh Thompson
Year of discovery	1971
Rules Outer-totalistic rules B3/S2 – B345678/S02345678 # of rules 212 = 4096 Isotropic rules B3i/S2i – B2-an345678/S01c2345678
Glider synthesis Fewest gliders 2 Uploaded synthesis RLE interchange_synth.rle
Pattern files Plaintext interchange.cells RLE interchange.rle
Identifiers apgcode xp2_ggg07y270gggzy0ey2e

Interchange is a common constellation of six blinkers.

There are two different interchanges; the more common one is displayed to the right. The less common variant has five cells between the left and right halves instead of four.

Two gliders reflected along an axis of symmetry with an even number of rows between them form an interchange. With an odd number of rows, it becomes a bi-block instead.

x = 7, y = 4, rule = B3/S23 3bo$b2ob2o$6bo$o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 4 THUMBSIZE 2 ]]

Unlike most common sequences which require only five or six cells the minimum number of cells needed to form an interchange is seven (click above to open LifeViewer) RLE: here Plaintext: here

Hasslers

Interchanges can be hassled, although not that many are known because the interchange doesn't expand as much as several more common sequences like the R-pentomino or Pi-heptomino.

x = 38, y = 28, rule = B3/S23 25b2o$22b2o2bo$22bo3bobo$23b3obobo$27bobo$3bo17b4ob2obob2o$2bobo15bo6b obob2o$2bobo10bo3bobobo5bo$2o2b2o8bobobobo3bo3b2o$bobo6b2o2bobobo6bo$o 2b3o4bobobobob2o11b2o$obo3bo5bobobo2bo5b3o3b2o$bob3obo4bo2bo2bo6b3o4bo $3bo3bo2bob2obo3bo10b5obo$3bo3bo2bob2obo3bo11b3o3bo$bob3obo4bo2bo2bo6b 3o8bo$obo3bo5bobobo2bo5b3o$o2b3o4bobobobob2o$bobo6b2o2bobobo6bo$2o2b2o 8bobobobo3bo3b2o$2bobo10bo3bobobo5bo$2bobo15bo6bobob2o$3bo17b4ob2obob 2o$27bobo$23b3obobo$22bo3bobo$22b2o2bo$25b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 5 THUMBSIZE 2 ]]

p9, found by David Raucci on January 24, 2022 (click above to open LifeViewer) Catagolue: here

x = 22, y = 24, rule = B3/S23 3b2o12b2o$3b2o12b2o2$b6o8b6o$o6bo6bo6bo$2o3b2o8b2o3b2o$4bo12bo2$3b3o 10b3o$3b3o10b3o$2ob3o2bo4bo2b3ob2o$o2b3o2bo4bo2b3o2bo$bob3o2bo4bo2b3ob o$2ob3o4b2o4b3ob2o$3b3o10b3o$3b3o10b3o2$4bo12bo$2o3b2o8b2o3b2o$o6bo6bo 6bo$b6o8b6o2$3b2o12b2o$3b2o12b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 8 THUMBSIZE 2 ]]

p16 pre-interchange hassler, found by Carson Cheng on October 8, 2022 (click above to open LifeViewer) Catagolue: here

x = 28, y = 27, rule = B3/S23 12bob2o4b2obo$12b2o2bo2bo2b2o$10b2o3bo4bo3b2o$bo2bo4bo3b2ob4ob2o3bo$4b o5b3obobo2bobob3o$o4bo6bobob4obobo$2o2bobo7bo2b2o2bo$5bob2o6b2o2b2o3$ 5bo2bo$5b2o6b2o$12b4o$11bo4bo$12b4o$13b2o6b2o$19bo2bo3$7b2o2b2o6b2obo$ 6bo2b2o2bo7bobo2b2o$4bobob4obobo6bo4bo$2b3obobo2bobob3o5bo$bo3b2ob4ob 2o3bo4bo2bo$2b2o3bo4bo3b2o$4b2o2bo2bo2b2o$4bob2o4b2obo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 9 THUMBSIZE 2 ]]

p18, found by David Raucci on October 3, 2021 and reduced by Matthias Merzenich the next day (click above to open LifeViewer) Catagolue: here

x = 43, y = 41, rule = B3/S23 5bo32bo$5bo32bo$5bo32bo$7b2o3bo18bo3b2o$b3o3b2o3b2o16b2o3b2o3b3o$14bo 14bo$13b2o14b2o3$2b2o31b2o$3bo32bo$3o30b3o$o32bo$5bo$6b2o$4b2o6b2o$6bo 3bo4bo$10bo4bo$10bo4bo10b2o$6b2o18bo$5bobo16bobo$5bo18b2o$4b2o10bo4bo$ 16bo4bo$16bo4bo3bo$18b2o6b2o$24b2o$26bo$10bo22bo$8b3o22b3o$7bo28bo$7b 2o26b2o3$13b2o14b2o$14bo14bo$b3o3b2o3b2o16b2o3b2o3b3o$7b2o3bo18bo3b2o$ 5bo32bo$5bo32bo$5bo32bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 19 THUMBSIZE 2 ]]

p38, found by cvojan on April 20, 2022 based on a partial by David Raucci (click above to open LifeViewer) Catagolue: here

x = 30, y = 24, rule = B3/S23 7bo14bo$2o4bobo12bobo4b2o$obo4bo14bo4bobo$2bo24bo$2b3o20b3o$5bo18bo$2b 3o20b3o$2bo24bo$obo7bo8bo7bobo$2o7bobo6bobo7b2o$8b2ob2o4b2ob2o$8bo3bo 4bo3bo$8bo3bo4bo3bo$8b2ob2o4b2ob2o$2o7bobo6bobo7b2o$obo7bo8bo7bobo$2b o24bo$2b3o20b3o$5bo18bo$2b3o20b3o$2bo24bo$obo4bo14bo4bobo$2o4bobo12bo bo4b2o$7bo14bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[GPS 23 THUMBSIZE 2 ]]

p40 interchange which is hassled in a similar fashion to the p84 below, but with stable supports. Incorrectly named "p40 moose honey farm hassler" on Catagolue. Found by Mitchell Riley. (click above to open LifeViewer) Catagolue: here

x = 32, y = 33, rule = B3/S23 19b2o$6o8b2o2b2obo5b2o$4o10b2o3bobo5b2o$3bobo15bo$5b2o16bo$2bo2bob2o$b o3bob2o14bo$2obo3bo13bo$2obo2bo7b2o3bobo5b2o$2b2o10b2o2b2obo5b2o$3bobo 13b2o$5b4o$3b6o3$13b2o2b2o$13b2o2b2o$13b2o2b2o3$23b6o$23b4o$11b2o13bob o$3b2o5bob2o2b2o10b2o$3b2o5bobo3b2o7bo2bob2o$10bo13bo3bob2o$8bo14b2obo 3bo$23b2obo2bo$8bo16b2o$10bo15bobo$3b2o5bobo3b2o10b4o$3b2o5bob2o2b2o8b 6o$11b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 23 THUMBSIZE 2 ]]

p42 that alternates between an interchange and a pentadecathlon, found by Period1GliderGun on May 2, 2024 (click above to open LifeViewer) Catagolue: here

x = 34, y = 17, rule = B3/S23 30bo$28b3o$7b2o18bo$7b2o18b2o$bo30bo$o2bo26bo2bo$o2bo12b2o12bo2bo$2bo 12b4o7b2o3bo$6b2o6bo4bo6b2o$2bo3b2o7b4o12bo$o2bo12b2o12bo2bo$o2bo26bo 2bo$bo30bo$5b2o18b2o$6bo18b2o$3b3o$3bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 23 THUMBSIZE 2 ]]

p46, found by Carson Cheng on September 22, 2023 (click above to open LifeViewer) Catagolue: here

x = 46, y = 50, rule = B3/S23 12bo$12b3o$15bo$14bobobobo$13bob3o3bo$13bobobo2bo$14bo2b2o$15bo2bo$b2o 5b2o26b2o5b2o$2bo5bo6bo3bo12bo4bo5bo$30b3o$16b3o10bo$3b2ob2o21b2o7b2ob 2o2$2bobobobo28bobobobo$bo7bo26bo7bo$o2bo3bo2bo24bo2bo3bo2bo$3o5b3o24b 3o5b3o4$b2o5b2o26b2o5b2o$b2o5b2o7b3o6b3o7b2o5b2o$17b3o6b3o3$17b3o6b3o$ b2o5b2o7b3o6b3o7b2o5b2o$b2o5b2o26b2o5b2o4$3o5b3o24b3o5b3o$o2bo3bo2bo 24bo2bo3bo2bo$bo7bo26bo7bo$2bobobobo28bobobobo2$3b2ob2o21b2o7b2ob2o$ 16b3o10bo$30b3o$2bo5bo6bo3bo12bo4bo5bo$b2o5b2o26b2o5b2o$15bo2bo$14bo2b 2o$13bobobo2bo$13bob3o3bo$14bobobobo$15bo$12b3o$12bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 42 THUMBSIZE 2 ]]

p84, found by David Raucci on July 22, 2021 (click above to open LifeViewer) Catagolue: here

x = 43, y = 32, rule = B3/S23 12bo$11bobo$12bo12b2o$25b2o$10b5o$9bo4bo5bo$8bo2bo7bobo$5bo2bob2o8bo$ 4bobobo5bo$5bo2bo4bobo$8b2o2bo2bo$13b2o19b2o4bo$34b2o3b3o$5bo32bob3o$ 4b3o19b2o2b2o5bo3bo$3bob3o3b2o2b2o9b2o2b2o4bo3bo$2bo3bo4b2o2b2o9b2o2b 2o3b3obo$bo3bo5b2o2b2o19b3o$3obo32bo$b3o3b2o$2bo4b2o19b2o$27bo2bo2b2o $27bobo4bo2bo$28bo5bobobo$22bo8b2obo2bo$21bobo7bo2bo$22bo5bo4bo$28b5o $16b2o$16b2o12bo$29bobo$30bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 HEIGHT 500 ]]

p88, found by Nora Brown on June 6, 2023. (click above to open LifeViewer) Catagolue: here

Other interactions

x = 11, y = 13, rule = B3/S23 9bo$8bo$8bo$2o5bo$o7bo$2bob2o2bo$b2obo5bo$2bo3bo$bo2bob3o$b4o4bo$6b3o$ 3b2obo$3bobo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 8 THUMBSIZE 2 ]]

A specific and fairly common interchange predecessor, when hitting a specific catalyst, becomes a LWSS. (click above to open LifeViewer)

See also

• Blinker
• Traffic light
• Traffic stop
• Cap, one of its predecessors

External links

• Interchange at the Life Lexicon
• Small interchange at Adam P. Goucher's Catagolue (pseudo-object)
• Large interchange at Adam P. Goucher's Catagolue (pseudo-object)