OCA:Marine
| Marine | |
| Rulestring | R2,C2,S4,6-9,B6-8,N@03ddef |
|---|---|
| Character | Chaotic |
|
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Marine is a higher-range outer-totalistic cellular automaton (abbreviated HROT) with weighted neighbourhood. It was devised by MathAndCode in September 2020.[1]
Rule definition and simulation
Like many outer-totalistic Life-like cellular automata, Marine has two states, runs on a 2d square grid, and the new state of a cell is a function of both the total number of live cells surrounding the cell, and the state of the cell itself. However, its neighbourhood is a 4×4 square, which does not have a cell exactly at the geometric center. To circumvent this issue, Moosey proposed to use a 5×5 square (equivalent to a range-2 neighbourhood of the center c) and assign different weights to the cells instead:
| 0 | 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 1 | 1 |
| 0 | 1 | c | 1 | 1 |
| 0 | 1 | 1 | 1 | 1 |
| 0 | 1 | 1 | 1 | 1 |
Concatenating the rows without c gives 000000111101110111101111 in binary, which equals to 03ddef in hexadecimal. Meanwhile, MathAndCode wrote the rulestring in the usual format for Life-like cellular automata as "B678S46789". Combining neighbourhood and transition function, the valid HROT specification becomes R2,C2,S4,6-9,B6-8,N@03ddef.
In the original introduction, Marine was simulated in a custom website (that made the discovery of a rule using a shifted square neighborhood more intuitive). As LifeViewer began supporting HROT rules in August, later patterns can be shared and viewed easily on the forum thread. Before Golly's support of HROT in version 4.0+ that started in October, CAViewer and Java Square Cell were two means of exploring the rule. For soup-searching, a ruletable (or "apgtable") was written to run this rule in apgsearch, and the results from which are uploaded to Catagolue under the name of "xmarine"; this is linked in External Link below.
Patterns
With the anisotropic neighbourhood definition above, patterns tend to evolve southeastwards; this direction is called downstream.
Still lives, oscillators, and guns
Many still lives, oscillators, and guns have two-cell-thick lines of cells on the north side and the west side that meet at a rounded corner. There are several strong composite sparkers, but their sparks are not as accessible as they otherwise would be because the sparks tend to go downstream instead of sidestream. However, it is still possible to combine sparkers to make guns of various periods.
Spaceships
There are three basic types spaceships known in Marine. Specifically, there are the squid, two types of minnow, and the bubble.
References
- ↑ MathAndCode (September 2, 2020). Re: Thread for your unsure discoveries (discussion thread) at the ConwayLife.com forums
External links
- Larger Than Life rule: Marine (discussion thread) at the ConwayLife.com forums