Periodic catalyst

A periodic catalyst is an oscillator that can act as a catalyst. An example of a periodic catalyst is toad, which can catalyse an octomino 2 like so:

2bo$3bo$3bo$2b2o$bo$o3bo$4b2o$4b2o$5bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 4 THUMBSIZE 2 AUTOSTART T 0 PAUSE 2 T 16 PAUSE 2 LOOP 17 ]]

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If, in the interaction between an active object and an oscillator, only the sparks of the oscillator (if any) are directly influencing the birth and/or death of the active object's cells, then the oscillator cannot be called a periodic catalyst.

Sometimes, custom period-3 or period-4 catalysts are found using a search program to complete an oscillator, as shown in this p69 pi-heptomino hassler.

x = 64, y = 42, rule = B3/S23 35b2o$35bobob2obo$37bobob2o$37b2o3$35b2o9b2o$35b2o9bo$44bobo$44b2o$18b o30bob3obobo3b2o$18b3o27bo7bobobobo$21bo26bo3bo2bo2bobo$20b2o28b4o3bo bobo$46b2o4bobo3b2obo$36b3o10bo4b2o2bo3b2o$36bo9bo8b2o3bobo$36b3o8bob 3o2b2o4bobo$48b4o2b3o4bo$51bo3$12bo$2bo4b3o2b4o$bobo4b2o2b3obo8b3o$bo bo3b2o8bo9bo$2o3bo2b2o4bo10b3o$2bob2o3bobo4b2o$2bobobo3b4o28b2o$3bobo 2bo2bo3bo26bo$bobobobo7bo27b3o$b2o3bobob3obo30bo$18b2o$17bobo$17bo9b2o $16b2o9b2o3$25b2o$21b2obobo$21bob2obobo$27b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 35 ZOOM 6 THUMBSIZE 2 ]]

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The term "periodic catalyst" can also refer to a catalyst which uses an oscillator that restores a transparent still life, rather than interacting with an active object, like with this pattern:

6b2o$3o2bo2bo$obo3b2o4bo$3o10b2o$11b2o$13bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 8 THUMBSIZE 2 ZOOM 14 AUTOSTART T 0 PAUSE 2 T 24 PAUSE 2 T 48 LOOP 49 ]]

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Some periodic catalysts can also function as stable catalysts: an example of this is Coe's p8 being used to convert a beehive to a block. This trick is exploited in p8 glider reflector and HRx74B. Other examples include test tube baby being used as an eater weld or the periodic Eater 2 replacements in 90P51 or 134P39.1.

x = 14, y = 7, rule = B3/S23 11b2o$2o8bo2bo$2o2b2o5b2o$5b2o$4bo2bo$7bo2b2o$5bobo2b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 4 THUMBSIZE 2 ZOOM 14 AUTOSTART T 0 PAUSE 2 T 8 PAUSE 2 LOOP 9 ]]

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See also

• Toad reaction
• Mazing, Antiphase why bother, traffic stop, 42P38, killer toads and killer candlefrobras, Fox+Clock catalyst - for more examples of oscillators acting as catalysts