Pattern naming

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Patterns in Conway's Game of Life and related cellular automata may be named in a variety of ways.

There are three ways to refer to a pattern:

  • A name designates the pattern.
  • A description provides information about the pattern and its parameters.
  • A code allows reconstruction of the pattern.

Proper names

Many common or notable patterns have proper names assigned to them, either by their discoverer or the Life community at large. Names are usually based on either the visual appearance of the pattern, its behavior, its extended Wechsler format, its parameters or other traits; examples include:

Composite patterns

House on house siamese table-on-table weld hat-siamese-hat

When a pattern is composed of two or more named parts, these are often said to be on or at each other; and is also used, especially when one object is an induction coil which depends on the other for stabilization without touching it. The composite pattern can also be referred to as a tie, especially if the two constituent objects are identical, or as a bridge if the objects are joined edge-to-edge.

For a more in-depth breakdown of induction coil-based naming, see the induction coil page.

Examples include:

In some cases, a combination of two identical patterns is called a bi-pattern, a mirrored pattern or a rotated pattern. Examples include:

Two fused objects are said to be siamese if unmodified, or weld if modified. Examples include:

Alignment

Main article: Isomer

Since the constituent parts of a pattern may sometimes be arranged in different ways, prefixes such as cis-, trans-, ortho-, meta-, para-, shift- and postfixes such as up and down are used to distinguish the possible alignments.

Cis- and trans- are used when two different, asymmetric induction coils align; they function as in organic chemistry. Cis- denotes a pattern where the "heavy" parts are on the same side, closer to each other, while trans- denotes a pattern where the "heavy" parts are on opposite sides; compare e.g. cis-loaf with tail and trans-loaf with tail.[1]

When two different, asymmetric induction coils disalign, ortho-, meta-, shift- and para- are used instead. If the constituent patterns point in opposite directions and their "heavy" parts align, ortho- is used; if their light parts align, meta- is used. If the patterns point in the same direction, and the first's heavy part aligns with the second's light part, shift- is used, while if the first's light part aligns with the second's heavy part, para- is used.[1]

Finally, up means that the stabilizer is pointing toward the "heavy" part of the induction coil, while down means the stabilizer is pointing away from it.[1]

Infinite families

Main article: Long

Many patterns can be extended arbitrarily in a systematic manner; the members of the family are then referred to as long, very long, extra long etc.

Other infinite families defying easy description exist, e.g. lakes; these are largely unnamed.

Systematic names (descriptions)

Patterns may be given systematic names based on their behavior and/or traits.

Shuttles, loops and oscillators may be named according to their period; for example, the p26 glider shuttle, p42 glider shuttle and p50 glider shuttle are all glider shuttles of various periods.

Conduits are named according to their step, direction, input and output objects; e.g. Fx176, HF110B and CL48C.

Sawtooths are often named according to their minimum recurring population, e.g. sawtooth 177, sawtooth 201 and sawtooth 1212.

Codes

See also Category:File formats.

Various encodings for patterns exist.

  • RLE is easy to encode and decode, but can grow fairly large, and does not uniquely identify a pattern.
  • Extended Wechsler codes (apgcodes) uniquely identify a periodic pattern, while also encoding its behavior in a given rule (assumed to be Conway Life unless otherwise specified).

Unnamed patterns are often encoded for communication using apgcodes or single-line headerless RLEs (e.g. 4bo$5b2o$obobo$obo!).

Indices in pattern collections

Patterns can also be referred to by their indices in pattern collections; for example, the hat is object 9.1 on Heinrich Koenig's Game of Life Object Catalogs. For stamp collections such as jslife, the file the object is contained in and its position on the grid can be used.

Pentadecathlon ID

Unnamed patterns may be referred to using a descriptor called "Pentadecathlon ID". It has been extensively used by Heinrich Koenig on his website, Game of Life Information.

For oscillators, the format of the descriptor is #p# (e.g. 30P3). The first number denotes the minimum population; second denotes the period. For spaceships, this is extended to #p#h#v# (e.g. 29P3H1V0); third and fourth number are the horizontal and vertical displacement of the spaceship relative to its initial position. Third number must be bigger than or equal to the fourth.

In either case, objects that would ordinarily be assigned the same descriptor may be distinguished by appending a period and an index, e.g. 28P7.1 and 28P7.2.

For unnamed methuselahs, the descriptor format is #M, with the number giving the number of generations until the pattern settles down, e.g. 40514M.

There are also descriptors for linear growth patterns, although these have not been used elsewhere in practice. For guns, the format is #p#a#, where the third number denotes how many cells the pattern grows by every period. For puffers and rakes, the format is #p#h#v#a# based on the spaceship notation.

References

  1. ↑ 1.0 1.1 1.2 EricABQ (2015-10-25 / 2015-11-11). "Comments on xp6_w8o0uh224a4z32". Catagolue. Retrieved on 2016-06-20.
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