Object

An object is defined as follows:

1. A cluster of adjacent living cells (e.g. block, tub, beacon, glider)
2. Two objects close to each other in such a way that they suppress one or more births that would occur if they were separated (e.g. aircraft carrier)
3. Two periodic objects that interact as described above in at least one of their phases (e.g. beacon, two pentadecathlons shuttling a glider)

Still-lifes are non-moving objects with a period of one. Oscillators are non-moving objects with a period greater than one. Spaceships are moving periodic objects.

Note that the word object is often use informally to mean a generic thing. The above formal definition is most useful when distinguishing among objects, pseudo-objects and quasi-objects.

Pseudo-object

A pseudo object is formed when two or more objects and/or pseudo-objects are close to each other in such a way that adjacent empty cells do not change their behaviors, but the reason births do not form is due to over-population rather than under-population, and there is at least one way that the clusters can be partitioned into disjoint sets that operate the same way (e.g. bi-block that can be partitioned into two blocks).

In most cases, this partitioning can be done into two sets, but there have been examples found that require three or even four sets (four is the maximum, given the 4-color map theorem).

Note that objects can fit this definition, but they are generally classed separately, in the same way that still-lifes are technically trivial period-1 oscillators but are not generally classified as such.

Pseudo-still-lifes, pseudo-oscillators, and pseudo-spaceships are pseudo-objects similar to the above (e.g. bi-block, beacon on block, LWSS-on-LWSS).

Quasi-object

A quasi-object is formed when two or more objects and/or pseudo-objects and/or or quasi-objects are close to each other in such a way that they share adjacent empty cells (e.g. two diagonally adjacent blocks).

Note that objects and pseudo-objects can fit this definition but are generally classed separately.

Quasi-still-lifes, quasi-oscillators and quasi-spaceships are quasi-objects similar to the above.

Gallery

Objects

x = 4, y = 3, rule = B3/S23 2b2o$o2bo$2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]] The two pre-blocks that form an aircraft carrier suppress the birth of the cell between them (click above to open LifeViewer) RLE: here Plaintext: here

2o$2o$2b2o$2b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 AUTOSTART GPS 2 ]] The two parts of a beacon suppress the birth of the cells between them every other tick (click above to open LifeViewer) RLE: here Plaintext: here

x = 35, y = 7, rule = B3/S23 2bo4bo$2ob4ob2o$2bo4bo$16bo$17b2o8bo4bo$16b2o7b2ob4ob2o$27bo4bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 AUTOSTART GPS 2 ]] Two pentadecathlons shuttling a glider (click above to open LifeViewer) RLE: here Plaintext: here

Pseudo-objects

x = 5, y = 2, rule = B3/S23 2ob2o$2ob2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]] A bi-block is a pseudo-still-life that can be partitioned into two block objects (click above to open LifeViewer) RLE: here Plaintext: here

x = 7, y = 4, rule = B3/S23 2b2ob2o$3bob2o$o$2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 AUTOSTART GPS 2 ]] Beacon on block is a pseudo-oscillator that can be partitioned into a beacon and a block (click above to open LifeViewer) RLE: here Plaintext: here

x = 11, y = 5, rule = B3/S23 b2o5b2o$3o5b3o$2obo3bob2o$b3o3b3o$2bo5bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ]] LWSS on LWSS is a pseudo-spaceship that can be partitioned into two LWSSes (click above to open LifeViewer) RLE: here Plaintext: here

Quasi-objects

2 blocks sharing a single diagonal cell (green) that is dead from underpopulation and remains so after separation

External links

• Four color theorem at Wikipedia