Glider (Conway's Game of Life)

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The mutation and movement of a "glider". Animated glider emblem.gif
The mutation and movement of a "glider".
A three-dimensional view of a glider, with previous generations visible going down the z-axis. The c/4 period is clearly visible as "stacks" of cells that remain alive for successive generations. Glider trail.png
A three-dimensional view of a glider, with previous generations visible going down the z-axis. The c/4 period is clearly visible as "stacks" of cells that remain alive for successive generations.

The glider is a pattern that travels across the board in Conway's Game of Life. It was first discovered by Richard K. Guy in 1969, while John Conway's group was attempting to track the evolution of the R-pentomino. Gliders are the smallest spaceships, and they travel diagonally at a speed of one cell every four generations, or . The glider is often produced from randomly generated starting configurations. [1]

Contents

The name comes from the fact that, after two steps, the glider pattern repeats its configuration with a glide reflection symmetry. After four steps and two glide reflections, it returns to its original orientation. [2] John Conway remarked that he wished he hadn't called it the glider. The game was developed before the widespread use of interactive computers, and after seeing it animated, he feels the glider looks more like an ant walking across the plane. [3]

Importance

Gliders are important to the Game of Life because they are easily produced, can be collided with each other to form more complicated objects, and can be used to transmit information over long distances. Instances of this second advantage are called glider syntheses. For instance, eight gliders can be positioned so that they collide to form a Gosper glider gun. [4] Glider collisions designed to result in certain patterns are also called glider syntheses. Patterns such as blocks, beehives, blinkers, traffic lights, even the uncommon Eater, can be synthesized with just two gliders. It takes three gliders to build the three other basic spaceships, and even the pentadecathlon oscillator.

Some patterns require a very large number (sometimes hundreds) of glider collisions; some oscillators, exotic spaceships, puffer trains, guns, etc. Whether the construction of an exotic pattern from gliders can possibly mean it can occur naturally, is still conjecture.

Gliders can also be collided with other patterns with interesting results. For example, if two gliders are shot at a block in just the right way, the block moves closer to the source of the gliders. If three gliders are shot in just the right way, the block moves farther away. This "sliding block memory" can be used to simulate a counter, which would be modified by firing gliders at it. It is possible to construct logic gates such as AND , OR and NOT using gliders. One may also build a pattern that acts like a finite state machine connected to two counters. This has the same computational power as a universal Turing machine, so, using the glider, the Game of Life is theoretically as powerful as any computer with unlimited memory and no time constraints: it is Turing complete. [5] [6]

Hacker emblem

Eric S. Raymond has proposed the glider as an emblem to represent the hacker subculture, as the Game of Life appeals to hackers, and the concept of the glider was "born at almost the same time as the Internet and Unix". [7] The emblem is in use in various places within the subculture. [8] [9]

Related Research Articles

<span class="mw-page-title-main">Conway's Game of Life</span> Two-dimensional cellular automaton

The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is a zero-player game, meaning that its evolution is determined by its initial state, requiring no further input. One interacts with the Game of Life by creating an initial configuration and observing how it evolves. It is Turing complete and can simulate a universal constructor or any other Turing machine.

<span class="mw-page-title-main">Cellular automaton</span> Discrete model studied in computer science

A cellular automaton is a discrete model of computation studied in automata theory. Cellular automata are also called cellular spaces, tessellation automata, homogeneous structures, cellular structures, tessellation structures, and iterative arrays. Cellular automata have found application in various areas, including physics, theoretical biology and microstructure modeling.

The hacker culture is a subculture of individuals who enjoy—often in collective effort—the intellectual challenge of creatively overcoming the limitations of software systems or electronic hardware, to achieve novel and clever outcomes. The act of engaging in activities in a spirit of playfulness and exploration is termed hacking. However, the defining characteristic of a hacker is not the activities performed themselves, but how it is done and whether it is exciting and meaningful. Activities of playful cleverness can be said to have "hack value" and therefore the term "hacks" came about, with early examples including pranks at MIT done by students to demonstrate their technical aptitude and cleverness. The hacker culture originally emerged in academia in the 1960s around the Massachusetts Institute of Technology (MIT)'s Tech Model Railroad Club (TMRC) and MIT Artificial Intelligence Laboratory. Hacking originally involved entering restricted areas in a clever way without causing any major damage. Some famous hacks at the Massachusetts Institute of Technology were placing of a campus police cruiser on the roof of the Great Dome and converting the Great Dome into R2-D2.

<span class="mw-page-title-main">Rule 110</span> Elementary cellular automaton

The Rule 110 cellular automaton is an elementary cellular automaton with interesting behavior on the boundary between stability and chaos. In this respect, it is similar to Conway's Game of Life. Like Life, Rule 110 with a particular repeating background pattern is known to be Turing complete. This implies that, in principle, any calculation or computer program can be simulated using this automaton.

<span class="mw-page-title-main">Highlife (cellular automaton)</span> 2D cellular automaton similar to Conways Game of Life

Highlife is a cellular automaton similar to Conway's Game of Life. It was devised in 1994 by Nathan Thompson. It is a two-dimensional, two-state cellular automaton in the "Life family" and is described by the rule B36/S23; that is, a cell is born if it has 3 or 6 neighbors and survives if it has 2 or 3 neighbors. Because the rules of HighLife and Conway's Life are similar, many simple patterns in Conway's Life function identically in HighLife. More complicated engineered patterns for one rule, though, typically do not work in the other rule.

<span class="mw-page-title-main">Spaceship (cellular automaton)</span> Type of pattern that periodically changes position

In a cellular automaton, a finite pattern is called a spaceship if it reappears after a certain number of generations in the same orientation but in a different position. The smallest such number of generations is called the period of the spaceship.

A cellular automaton (CA) is Life-like if it meets the following criteria:

<span class="mw-page-title-main">Seeds (cellular automaton)</span> 2D cellular automaton similar to Conways Game of Life

Seeds is a cellular automaton in the same family as the Game of Life, initially investigated by Brian Silverman and named by Mirek Wójtowicz. It consists of an infinite two-dimensional grid of cells, each of which may be in one of two states: on or off. Each cell is considered to have eight neighbors, as in Life. In each time step, a cell turns on or is "born" if it was off or "dead" but had exactly two neighbors that were on; all other cells turn off. Thus, in the notation describing the family of cellular automata containing Life, it is described by the rule B2/S.

<span class="mw-page-title-main">Gun (cellular automaton)</span> Cellular automaton pattern that emits spaceships

In a cellular automaton, a gun is a pattern with a main part that repeats periodically, like an oscillator, and that also periodically emits spaceships. There are then two periods that may be considered: the period of the spaceship output, and the period of the gun itself, which is necessarily a multiple of the spaceship output's period. A gun whose period is larger than the period of the output is a pseudoperiod gun.

<span class="mw-page-title-main">Block cellular automaton</span> Kind of cellular automaton

A block cellular automaton or partitioning cellular automaton is a special kind of cellular automaton in which the lattice of cells is divided into non-overlapping blocks and the transition rule is applied to a whole block at a time rather than a single cell. Block cellular automata are useful for simulations of physical quantities, because it is straightforward to choose transition rules that obey physical constraints such as reversibility and conservation laws.

In Conway's Game of Life and other cellular automata, a still life is a pattern that does not change from one generation to the next. The term comes from the art world where a still life painting or photograph depicts an inanimate scene. In cellular automata, a still life can be thought of as an oscillator with unit period.

Glider or Gliders may refer to:

<span class="mw-page-title-main">Rake (cellular automaton)</span> Type of moving pattern which periodically produces spaceships

A rake, in the lexicon of cellular automata, is a type of puffer train, which is an automaton that leaves behind a trail of debris. In the case of a rake, however, the debris left behind is a stream of spaceships, which are automata that "travel" by looping through a short series of iterations and end up in a new location after each cycle returns to the original configuration.

<span class="mw-page-title-main">Reflector (cellular automaton)</span> Type of pattern that can redirect a stream of incoming spaceships

In cellular automata such as Conway's Game of Life, a reflector is a pattern that can interact with a spaceship to change its direction of motion, without damage to the reflector pattern. In Life, many oscillators can reflect the glider; there also exist stable reflectors composed of still life patterns that, when they interact with a glider, reflect the glider and return to their stable state.

<span class="mw-page-title-main">Spark (cellular automaton)</span> Type of pattern which temporarily appears at the edge of a larger pattern

In Conway's Game of Life and similar cellular automaton rules, a spark is a small collection of live cells that appears at the edge of some larger pattern such as a spaceship or oscillator, then quickly dies off.

In Conway's Game of Life, the speed of light is a propagation rate across the grid of exactly one step per generation. In a single generation, a cell can only influence its nearest neighbours, and so the speed of light is the maximum rate at which information can propagate. It is therefore an upper bound to the speed at which any pattern can move.

<span class="mw-page-title-main">Brian's Brain</span> 2D cellular automaton devised by Brian Silverman

Brian's Brain is a cellular automaton devised by Brian Silverman, which is very similar to his Seeds rule.

<span class="mw-page-title-main">Life without Death</span> 2D cellular automaton similar to Conways Game of Life

Life without Death is a cellular automaton, similar to Conway's Game of Life and other Life-like cellular automaton rules. In this cellular automaton, an initial seed pattern grows according to the same rule as in Conway's Game of Life; however, unlike Life, patterns never shrink. The rule was originally considered by Toffoli & Margolus (1987), who called it "Inkspot"; it has also been called "Flakes". In contrast to the more complex patterns that exist within Conway's Game of Life, Life without Death commonly features still life patterns, in which no change occurs, and ladder patterns, that grow in a straight line.

<span class="mw-page-title-main">Golly (program)</span> Tool for simulating cellular automata

Golly is a tool for the simulation of cellular automata. It is free open-source software written by Andrew Trevorrow and Tomas Rokicki; it can be scripted using Lua or Python. It includes a hashlife algorithm that can simulate the behavior of very large structured or repetitive patterns such as Paul Rendell's Life universal Turing machine, and that is fast enough to simulate some patterns for 232 or more time units. It also includes a large library of predefined patterns in Conway's Game of Life and other rules.

<span class="mw-page-title-main">Critters (cellular automaton)</span>

Critters is a reversible block cellular automaton with similar dynamics to Conway's Game of Life, first described by Tommaso Toffoli and Norman Margolus in 1987.

References

  1. Flammenkamp, Achim (December 9, 1995). "Spontaneous appeared Spaceships out of Random Dust". Bielefeld University. Archived from the original on April 13, 2009. Retrieved February 27, 2009.
  2. Wainwright, Robert T. (1974). "Life is universal!". Proceedings of the 7th conference on Winter simulation - WSC '74. ACM Press. doi: 10.1145/800290.811303 .
  3. Haran, Brady (March 3, 2014). Does John Conway hate his Game of Life?. YouTube. Archived from the original on December 22, 2021. Retrieved May 9, 2014.
  4. Niemiec, Mark D. (2010). "Object synthesis in Conway's Game of Life and other cellular automata". In Adamatzky, Andrew (ed.). Game of Life Cellular Automata. Springer-Verlag. pp. 115–134. doi:10.1007/978-1-84996-217-9_8. Fig. 8.12 on p. 129 depicts a closely related synthesis with seven gliders and a block. The 8-glider synthesis combines two of the four-glider units described in this figure.
  5. Chapman, Paul (November 11, 2002). "Life Universal Computer". Igblan. Archived from the original on September 6, 2009. Retrieved July 12, 2009.
  6. Berlekamp, E. R.; Conway, John Horton; Guy, Richard K. (2004). Winning ways for your mathematical plays (2nd ed.). Natick, Mass: A K Peters. ISBN   156881142X. OCLC   560267317.
  7. Raymond, Eric S. "Frequently Asked Questions about the Glider Emblem". catb.org. Archived from the original on September 12, 2016. Retrieved November 5, 2012.
  8. "BlueHackers Logo". BlueHackers. Archived from the original on June 18, 2017. Retrieved July 17, 2017.
  9. Hinton, Andrew (May 16, 2007). "The Glider as Hacker Emblem". inkblurt. Archived from the original on July 8, 2017. Retrieved July 17, 2017.