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Rock-paper-scissors (also known as paper-scissors-rock, scissors-paper-stone, jan-ken-pon, rochambeau (sometimes spelled roshambo) and many derived terms^[1]), is a popular two-person hand game.

The game is often used as a selection method in a similar way to coin flipping, drawing straws, or throwing dice to randomly select a person for some purpose. However, unlike truly random selections, it can be played with skill if the game extends over many sessions, as a player can often recognize and exploit the non-random behavior of an opponent.

Sportspeople often use the game (both officially and unofficially, in place of a coin toss) to decide on opening plays. Similarly, uncertain calls, or even the whole game in case of rain, may be so decided.^{[citation needed]} It is also often used as a method for creating appropriately non-biased random results in live action role-playing games, as it requires no equipment. It is also used in some online gambling sites as a form of novelty betting.

Game play


Each of the three basic hand-signs ( from left to right: rock, paper and scissors ) beats one of the other two.

The players both count aloud to three, or speak the name of the game (e.g. "Rock! Paper! Scissors!" or "Ro! Cham! Beau!"), each time raising one hand in a fist and swinging it down on the count. On the third count (saying "scissors!" or "Beau!" ), the players change their hands into one of three gestures, which they then "throw" by extending it towards their opponent. A variation on this version (played in the United States) involves a fourth count—"SHOOT"—before players throw their gesture.

Rock, represented by a clenched fist.
Paper, represented by an open hand, with the fingers connected.
Scissors, represented by the index and middle fingers extended and separated.

The objective is to select a gesture which defeats that of the opponent. Gestures are resolved as follows:

Rock blunts or crushes scissors; rock wins.
Paper covers or captures rock; paper wins.
Scissors cut paper; scissors win.

If both players choose the same gesture, the game is tied and the players throw again. If the gestures chosen on each throw were truly random, the average number of throws required to decide a winner would be 1.5. ^[2]

In some variations of the game, the winner of each round "uses" the weapon on the opponent's weapon, to demonstrate that they have won. Otherwise the game is settled.

Rock-paper-scissors (RPS) is frequently played in a "best two out of three" match, and tournament players often prepare sequences of three gestures ahead of time.^[3]^[4]

Jason Simmons, a competitive RPS champion, claims that women tend to start with scissors,^[5] while the World RPS Society states that males have a tendency to lead with rock. At World RPS tournaments, scissors is statistically the least common throw.^[6]

Mathematics: intransitivity

RPS is also often used as an example of the mathematical concept of non-transitive relations. A transitive relation R is one for which a R b and b R c implies a R c. A reflexive, antisymmetric, and transitive relation on a set is known as a partial ordering, from which notions of "greater" and "less" follow. A game option which is "greater" than another is closer to being optimal, but such a notion does not exist in RPS: The relation used to determine which throws defeat which is non-transitive. Rock defeats scissors, and scissors defeat paper, but rock loses to paper. In fact, RPS could be called "intransitive" because A is greater than B, and B is greater than C, yet A is not greater than C. The game is thus an example of a Strange loop, or apparent hierarchy that returns to an earlier level.

In knot theory and braid theory, the Borromean rings and the standard braid exhibit rock-paper-scissors ordering. This gives rise to what is called the Brunnian property: any pair of Borromean rings is unlinked, and any two strands of a standard braid are not braided around each other, so if any one ring or strand is removed they will come apart, but the overall link or braid does not come apart.

Red is over yellow, yellow is over blue, blue is over red
Blue is over red, red is over black, black is over blue

Variations

Players have developed numerous cultural and personal variations on the game, from simply playing the same game with different objects, to expanding into more weapons.

Substitution of weapons

In Indonesia, particularly Central Java, children play a variation that has the same rules but entirely different weapons and gestures. As in the Japanese RPS game, they say jan-ken-pon while pumping the fist before selecting a weapon.

An extended thumb is called "elephant". An extended forefinger is called "human being". An extended little finger is called "ant".

Elephant crushes human, human crushes ant, and ant kills elephant by entering its trunk.

Additional weapons

With an odd number of choices, each beats half the weapons and loses to half the weapons. No even number of weapons can be made balanced, unless some pairs of weapons result in a draw; there will always be some weapons superior to others. These also lose some of the aesthetic elegance of the game, which is otherwise one of the simplest possible games of skill.

An example of an unbalanced four-weapon game adds "dynamite" as a trump. Dynamite, expressed as the extended index finger or thumb, always defeats rock, but is defeated by scissors. The paper-dynamite relationship is disputed; using it as a trump generally implies that "dynamite shreds paper," but there are those who claim that the paper would supposedly smother the wick. Because of this dispute (and the potential unfair advantage that would result), organized rock-paper-scissors contests never use dynamite.^[7]

The official roshambo rules of the Ultimate Players Association add "fire" and "water" as potential trumps. Fire will beat any of the standard weapons (rock, paper, scissors), but a player may only throw it once in his entire lifetime. Water may be played as many times as one wishes, but loses to any throw except fire. (Those who adopt this trump depend on good sportsmanship to enforce the once-per-lifetime rule.)^[8]

One popular balanced five-weapon expansion, invented by Sam Kass,^[9] adds "Spock" and "lizard" to the standard three. "Spock" is signified with the "live long and prosper" hand gesture, while "lizard" is shown by forming the hand into a sock-puppet-like mouth. Spock crushes scissors and vaporizes rock; he is poisoned by the lizard and disproved by the paper. Lizard poisons Spock and eats paper; it is crushed by the rock and decapitated by the scissors. This variant was covered in a 2005 article of The Times,^[10] and appeared in an episode of the sitcom The Big Bang Theory in 2008.^[11]

"The Ultimate Rock, Paper, Scissors Chart", contains no fewer than 25 possible hand shapes.^[12]

A new "most terrifyingly complex" game of RPS was posted online in 2006 that has 101 different gestures and 5050 possible non-tie outcomes.^[13] All information on playing is available online but a poster and a booklet outlining the gestures and outcomes were also made available for purchase. A notable difference from the 25 hand shape version is that now nuke beats wolf rather than the other way around.

Different weapons

A variation found in Indonesia is composed of an earwig, a human, and an elephant. The earwig is able to climb into the elephant's ear and drive it insane, while the human crushes the earwig and the elephant crushes the human.^[14]

The popular television series That '70s Show mentions a nuclear war-like version. The cockroach survives the nuclear bomb, the nuclear bomb destroys the foot (or human as it may apply), and the foot/human crushes the cockroach.

The Discovery Kids television series Endurance uses an elimination scheme that involves wood, water and fire. (The operating premise is that fire "burns", and therefore defeats, wood; wood "floats on" and defeats water; and water extinguishes fire.)

Rock-paper-scissors analogies in computing

Combat or strategy-based video games often feature RPS-like cycles in their characters' or units' effectiveness against others. These often attempt to emulate cycles in real-world combat (such as where cavalry are effective against archers, archers have an edge over spearmen, and spearmen are strongest against cavalry.) Such game mechanics can make a game somewhat self-balancing, by preventing any one simple strategy from dominating gameplay.

Many card-based video games in Japan use the RPS system as their core fighting system, with the winner of each round being able to carry out their designated attack. (A popular game involving an extended RPS strategy is Pokémon, in which attacks have varied effectiveness based on 17 elemental types.)

Some class-based first person shooter games, such as Team Fortress 2, use the same self-balancing mechanism. Certain classes are designed with clear strength or weaknesses against other classes, which encourages players to respond to the changing battlefield and coordinate their efforts.

Rock-paper-scissors analogies in nature

Lizard mating strategies

The common side-blotched lizard (Uta stansburiana) exhibits a RPS pattern in its mating strategies. Of its three color types of males, "orange beats blue, blue beats yellow, and yellow beats orange" in competition for females, which is similar to the rules of rock-paper-scissors.

Coliform bacteria

Some bacteria also exhibit a rock-paper-scissors dynamic when they engage in antibiotic production. The theory for this finding was demonstrated by computer simulation and in the laboratory by Benjamin Kerr, working at Stanford University with Brendan Bohannan.^[15] The antibiotics in question are the bacteriocins - more specifically, colicins produced by Escherichia coli. Biologist Benjamin C. Kirkup, Jr. further demonstrated that the colicins were active as E. coli compete with each other in the intestines of mice, and that the rock-paper-scissors dynamics allowed for the continued competition between strains: antibiotic-producers defeat antibiotic-sensitives; antibiotic-resisters multiply and withstand and out-compete the antibiotic-producers, letting antibiotic-sensitives multiply and out-compete others; until antibiotic-producers multiply again.^[16]

Cultural references

Because of its widespread use, the game has received substantial references in popular culture. Many television series poke fun at particular characters' incompetence at understanding the rules, or show how mischievous characters are often able to "win" the game by inventing new objects which beat all the others.

Federal case

In 2006, Federal Judge Gregory Presnell from the Middle District of Florida ordered opposing sides in a lengthy court case to settle a trivial (but lengthily debated) point over the appropriate place for a deposition using the game of rock-paper-scissors.^[17] The ruling in Avista Management v. Wausau Underwriters stated:

Upon consideration of the Motion – the latest in a series of Gordian knots that the parties have been unable to untangle without enlisting the assistance of the federal courts – it is ORDERED that said Motion is DENIED. Instead, the Court will fashion a new form of alternative dispute resolution, to wit: at 4:00 P.M. on Friday, June 30, 2006, counsel shall convene at a neutral site agreeable to both parties. If counsel cannot agree on a neutral site, they shall meet on the front steps of the Sam M. Gibbons U.S. Courthouse, 801 North Florida Ave., Tampa, Florida 33602. Each lawyer shall be entitled to be accompanied by one paralegal who shall act as an attendant and witness. At that time and location, counsel shall engage in one (1) game of "rock, paper, scissors." The winner of this engagement shall be entitled to select the location for the 30(b)(6) deposition to be held somewhere in Hillsborough County during the period July 11-12, 2006.
— ^[18]

The public release of this judicial order, widely circulated among area lawyers, was intended to shame the respective law firms regarding their litigation conduct by settling the dispute in a farcical manner.^{[citation needed]}

Auction house RPS match

When Takashi Hashiyama, CEO of a Japanese television equipment manufacturer, decided to auction off the collection of Impressionist paintings owned by his corporation, including works by Cézanne, Picasso and van Gogh, he contacted two leading U.S. auction houses, Christie's International and Sotheby's Holdings, seeking their proposals on how they would bring the collection to the market as well as how they would maximize the profits from the sale. Both firms made elaborate proposals, but neither was persuasive enough to get Hashiyama’s business. Unwilling to split up the collection into separate auctions, Hashiyama asked the firms to decide between themselves who would hold the auction, which included Cézanne's "Large Trees Under the Jas de Bouffan", worth $12–16 million.

The houses were unable to reach a decision. Hashiyama told the two firms to play RPS, to decide who would get the rights to the auction, explaining that "it probably looks strange to others, but I believe this is the best way to decide between two things which are equally good".

The auction houses had a weekend to come up with a choice of move. Christie's went to the 11-year-old twin daughters of an employee, who suggested "scissors" because "Everybody expects you to choose 'rock'." Sotheby's said that they treated it as a game of chance and had no particular strategy for the game, but went with "paper".^[20]

Christie's won the match, with millions of dollars of commission for the auction house.

Tournaments

WRPS sanctioned tournaments

Starting in 2002, the World Rock Paper Scissors Society (WRPS) standardized a set of rules for international play^[21] and has overseen annual International World Championships. These open, competitive championships have been widely attended by players from around the world and have attracted widespread international media attention.^[22]^[23]^[24]^[25]^[26] WRPS events are noted for their large cash prizes, elaborate staging, and colorful competitors.^[27] In 2004, the championships were broadcast on the U.S. television network Fox Sports Net, with the winner being Lee Rammage, who went on to compete in at least one subsequent championship.^[28]^[29]

Year	World Champion	Country
2002	Peter Lovering	Canadian
2003	Rob Krueger	Canadian
2004	Lee Rammage	Canadian
2005	Andrew Bergel	Canadian
2006	Bob Cooper	British
2007	Jamie "Landshark" Langridge	American
2008	?	?

USARPS Tournaments

USA Rock Paper Scissors League (USARPS) is a US-based rock-paper-scissors league. It is sponsored by Bud Light. Matti Leshem is the commissioner of the USARPS.

In April 2006, the inaugural USARPS Championship was held in Las Vegas, Nevada. Following months of regional qualifying tournaments held across the US, 257 players were flown to Las Vegas for a single-elimination tournament at the House of Blues where the winner received $50,000. The tournament was shown on the A&E Network on June 12, 2006.

The $50,000 2007 USARPS Tournament took place at the Las Vegas Mandalay Bay in May 2007.

In 2008, Sean Sears beat out 300 other contestants and walked out of the Mandalay Bay Hotel & Casino with $50,000.

The inaugural Budweiser International Rock, Paper, Scissors Federation Championship was held in Beijing, China after the close of the 2008 Summer Olympic Games. A Belfast man won the competition.^[30]

National XtremeRPS Competition 2007-2008

The XtremeRPS National Competition^[31] is a US nationwide RPS competition with Preliminary Qualifying contests that started in January 2007 and ended in May 2008, followed by regional finals in June and July 2008. The national finals were to be held in Des Moines in August 2008, with a chance to win up to $5,000.

Guinness Book of World Records

On April 3 2009, Colonel By Secondary School in Ottawa, Canada, held the largest recorded rock-paper-scissors tournament, with approximately 1150 participants. The contest was throughout all the Grade 9-12s, and included teachers. The winner, Cody Lombardo, took home a trophy, and had his name in the Guinness Book of World Records.^[32]

Notes

^ "Ready, set ... Roshambo! Contestants vie for $1,000 purse in Rock, Scissors, Paper contest". San Francisco Chronicle. Retrieved 2007-11-20.
^
This is based on a infinite series with three of nine possible outcomes being a tie. That is:
- On the first throw, there is a 1/3^rd chance of a tie and a 2/3^rds chance of a winner.
- There is only a 1/3^rd chance of a second throw being necessary, but if there is one, there is again a 2/3^rds chance of a winner for a 2/9^ths chance of two throws being necessary.
- There is only a 1/3^rd times 1/3^rd chance of a third throw and a 2/3^rds chance of a winner for a 2/27^ths need for three throws.
- And so on that when summed produces a value of 1.5 at the limit, thus the average number of throws required.
^ Steve Vockrodt, "Student rivals throw down at rock, paper, scissors tournament", Lawrence Journal-World, April 8, 2007, retrieved April 13, 2007.
^ Michael Y. Park, "Rock, Paper, Scissors, the Sport", Fox News, March 20, 2006, retrieved April 13, 2007.
^ Steve Inskeep, "In the News and On the Air: Iraq, Paper, Scissors", Morning E-dition, NPR.org, November 10, 2006. Retrieved April 13, 2007
^ Graham Walker, "How to beat anyone at Rock Paper Scissors", World RPS Society, 2006, Retrieved April 13, 2007.
^ World RPS Society (2002). "The Myth of Dynamite Exposed". Retrieved 2007-11-09.)
^ Ultimate Players Association (2004-09-04). "Ro-Sham-Bo (The Official UPA Rules)". Retrieved 2007-11-09. {{cite web}}: Check date values in: |date= (help)
^ Sam Kass. "Original Rock-Paper-Scissors-Spock-Lizard Page". Retrieved 2009-03-11.
^ http://www.timesonline.co.uk/tol/comment/leading_article/article1080425.ece
^ Officially released Youtube video
^ http://baseballbatyouth.com/Rock_Paper_Scissors.html
^ http://www.umop.com/rps101/rps101chart.html
^ Iona and Peter Opie. "Children's Games in Street and Playground". Retrieved 2008-03-10.
^ Nature. 2002 Jul 11;418(6894):171-4
^ Nature. 2004 Mar 25;428(6981):412-4
^ "Exasperated judge resorts to child's game". Associated Press. 2006-06-26. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)
^ Presnell, Gregory (June 7, 2006). "Order of the court: Avista Management vs. Wausau Underwriters Insurance Co". CNN.com. Retrieved 2006-06-08.
^ Art/Auctions logo, Impressionist & Modern Art, Christie's, 7PM, May 4, 2005, Sale 1514.
^ Vogel, Carol (April 29 2005), "Rock, Paper, Payoff: Child's Play Wins Auction House an Art Sale", New York Times {{citation}}: Check date values in: |date= (help)
^ "Game Basics". World Rock Paper Scissors Society. Retrieved 2006-08-20.
^ Hruby, Patrick (2004-12-10). "Fists fly in game of strategy". Washington Times. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)
^ "2003 World Rock Paper Scissors Championship". All Things Considered. National Public Radio. 2003-10-24. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)
^ "Rock, Paper, Scissors A Sport?". CBS News. 2003-10-23. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)
^ "Rock Paper Scissors contest being held". Associated Press. 2003-10-27. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)
^ Park, Michael Y. (2006-03-20). "Rock, Paper, Scissors, the Sport". Fox News. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)
^ "Gallery". World RPS society. 2005-11-13. Retrieved 2006-08-20. {{cite web}}: Check date values in: |date= (help)
^ http://money.cnn.com/magazines/fortune/fortune_archive/2005/06/13/8262549/index.htm
^ http://www.stanley-paul.com/index.php?option=com_gallery2&Itemid=30&g2_view=core.ShowItem&g2_itemId=16
^ http://www.examiner.ie/breaking/ireland/mhqlojkfidsn/
^ "XTreme RPS Competition by Showtime Entertainment". Retrieved 2007-01-07.
^ Sherwin, Fred. "Colonel By sets new World Record for largest rock, paper, scissors tournament". Orleans Online. Retrieved 2009-04-04.

References

Alonzo, Suzanne H. & Sinervo, Barry (2001): Mate choice games, context-dependent good genes, and genetic cycles in the side-blotched lizard, Uta stansburiana. Behavioral Ecology Sociobiology 49(2-3): 176–186. doi:10.1007/s002650000265 (HTML abstract)
Culin, Stewart (1895): Korean Games, With Notes on the Corresponding Games at China and Japan. (evidence of nonexistence of rock-paper-scissors in the West)
Gomme, Alice Bertha (1894, 1898): The traditional games of England, Scotland, and Ireland, 2 vols. (more evidence of nonexistence of rock-paper-scissors in the West)
Opie, Iona & Opie, Peter (1969): Children's Games in Street and Playground Oxford University Press, London. (Details some variants on rock-paper-scissors such as 'Man, Earwig, Elephant' in Indonesia, and presents evidence for the existence of 'finger throwing games' in Egypt as early as 2000 B.C.)
Sinervo, Barry (2001): Runaway social games, genetic cycles driven by alternative male and female strategies, and the origin of morphs. Genetica 112-113(1): 417-434. doi:10.1023/A:1013360426789 (HTML abstract)
Sinervo, Barry & Clobert, Jean (2003): Morphs, Dispersal Behavior, Genetic Similarity, and the Evolution of Cooperation. Science 300(5627): 1949-1951. doi:10.1126/science.1083109 (HTML abstract) Supporting Online Material
Sinervo, Barry & Lively, C. M. (1996): The Rock-Paper-Scissors Game and the evolution of alternative male strategies. Nature 380: 240-243. doi:10.1038/380240a0 (HTML abstract)
Sinervo, Barry & Zamudio, K. R. (2001): The Evolution of Alternative Reproductive Strategies: Fitness Differential, Heritability, and Genetic Correlation Between the Sexes. Journal of Heredity 92(2): 198-205. PDF fulltext
Sogawa, Tsuneo (2000): Janken. Monthly Sinica 11(5). [Article in Japanese]
Walker, Douglas & Walker, Graham (2004): The Official Rock Paper Scissors Strategy Guide. Fireside. (RPS strategy, tips and culture from the World Rock Paper Scissors Society).

External links

USA Rock Paper Scissors League
World Rock Paper Scissors Society
Abrams, Michael (2004-07-05). "Throwing for The Gold". Pursuits. Forbes FYI. Retrieved 2007-04-09. {{cite web}}: Check date values in: |date= (help); Italic or bold markup not allowed in: |publisher= (help)
Hegan, Ken (2004-01-07). "Hand to Hand Combat: Down and dirty at the World Rock Paper Scissors Championship". Rolling Stone Feature Article. Retrieved 2009-03-30. {{cite web}}: Check date values in: |date= (help); Italic or bold markup not allowed in: |publisher= (help)

[1] "Ready, set ... Roshambo! Contestants vie for $1,000 purse in Rock, Scissors, Paper contest". San Francisco Chronicle. Retrieved 2007-11-20.

[2] This is based on a infinite series with three of nine possible outcomes being a tie. That is:
On the first throw, there is a 1/3^rd chance of a tie and a 2/3^rds chance of a winner.

There is only a 1/3^rd chance of a second throw being necessary, but if there is one, there is again a 2/3^rds chance of a winner for a 2/9^ths chance of two throws being necessary.

There is only a 1/3^rd times 1/3^rd chance of a third throw and a 2/3^rds chance of a winner for a 2/27^ths need for three throws.

And so on that when summed produces a value of 1.5 at the limit, thus the average number of throws required.

[3] On the first throw, there is a 1/3^rd chance of a tie and a 2/3^rds chance of a winner.

[4] There is only a 1/3^rd chance of a second throw being necessary, but if there is one, there is again a 2/3^rds chance of a winner for a 2/9^ths chance of two throws being necessary.

[5] There is only a 1/3^rd times 1/3^rd chance of a third throw and a 2/3^rds chance of a winner for a 2/27^ths need for three throws.

[6] And so on that when summed produces a value of 1.5 at the limit, thus the average number of throws required.

[Lawrence_Journal-World-3] Steve Vockrodt, "Student rivals throw down at rock, paper, scissors tournament", Lawrence Journal-World, April 8, 2007, retrieved April 13, 2007.

[Fox_News-4] Michael Y. Park, "Rock, Paper, Scissors, the Sport", Fox News, March 20, 2006, retrieved April 13, 2007.

[Morning_E-dition-5] Steve Inskeep, "In the News and On the Air: Iraq, Paper, Scissors", Morning E-dition, NPR.org, November 10, 2006. Retrieved April 13, 2007

[How_to_beat_anyone-6] Graham Walker, "How to beat anyone at Rock Paper Scissors", World RPS Society, 2006, Retrieved April 13, 2007.

[7] World RPS Society (2002). "The Myth of Dynamite Exposed". Retrieved 2007-11-09.)

[8] Ultimate Players Association (2004-09-04). "Ro-Sham-Bo (The Official UPA Rules)". Retrieved 2007-11-09. {{cite web}}: Check date values in: |date= (help)

[9] Sam Kass. "Original Rock-Paper-Scissors-Spock-Lizard Page". Retrieved 2009-03-11.

[TimesSpockLizard-10] ttp://www.timesonline.co.uk/tol/comment/leading_article/article1080425.ece

[11] Officially released Youtube video

[12] ttp://baseballbatyouth.com/Rock_Paper_Scissors.html

[13] ttp://www.umop.com/rps101/rps101chart.html

[14] Iona and Peter Opie. "Children's Games in Street and Playground". Retrieved 2008-03-10.

[15] Nature. 2002 Jul 11;418(6894):171-4

[16] Nature. 2004 Mar 25;428(6981):412-4

[17] "Exasperated judge resorts to child's game". Associated Press. 2006-06-26. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)

[18] Presnell, Gregory (June 7, 2006). "Order of the court: Avista Management vs. Wausau Underwriters Insurance Co". CNN.com. Retrieved 2006-06-08.

[CityReview-19] Art/Auctions logo, Impressionist & Modern Art, Christie's, 7PM, May 4, 2005, Sale 1514.

[20] Vogel, Carol (April 29 2005), "Rock, Paper, Payoff: Child's Play Wins Auction House an Art Sale", New York Times {{citation}}: Check date values in: |date= (help)

[21] "Game Basics". World Rock Paper Scissors Society. Retrieved 2006-08-20.

[22] Hruby, Patrick (2004-12-10). "Fists fly in game of strategy". Washington Times. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)

[23] "2003 World Rock Paper Scissors Championship". All Things Considered. National Public Radio. 2003-10-24. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)

[24] "Rock, Paper, Scissors A Sport?". CBS News. 2003-10-23. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)

[25] "Rock Paper Scissors contest being held". Associated Press. 2003-10-27. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)

[26] Park, Michael Y. (2006-03-20). "Rock, Paper, Scissors, the Sport". Fox News. Retrieved 2006-08-20. {{cite news}}: Check date values in: |date= (help)

[27] "Gallery". World RPS society. 2005-11-13. Retrieved 2006-08-20. {{cite web}}: Check date values in: |date= (help)

[28] ttp://money.cnn.com/magazines/fortune/fortune_archive/2005/06/13/8262549/index.htm

[29] ttp://www.stanley-paul.com/index.php?option=com_gallery2&Itemid=30&g2_view=core.ShowItem&g2_itemId=16

[30] ttp://www.examiner.ie/breaking/ireland/mhqlojkfidsn/

[31] "XTreme RPS Competition by Showtime Entertainment". Retrieved 2007-01-07.

[32] Sherwin, Fred. "Colonel By sets new World Record for largest rock, paper, scissors tournament". Orleans Online. Retrieved 2009-04-04.

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v t e Topics of game theory
Definitions	Congestion game Cooperative game Determinacy Escalation of commitment Extensive-form game First-player and second-player win Game complexity Graphical game Hierarchy of beliefs Information set Normal-form game Preference Sequential game Simultaneous game Simultaneous action selection Solved game Succinct game Mechanism design
Equilibrium concepts	Bayes correlated equilibrium Bayesian Nash equilibrium Berge equilibrium Core Correlated equilibrium Coalition-proof Nash equilibrium Epsilon-equilibrium Evolutionarily stable strategy Gibbs equilibrium Mertens-stable equilibrium Markov perfect equilibrium Nash equilibrium Pareto efficiency Perfect Bayesian equilibrium Proper equilibrium Quantal response equilibrium Quasi-perfect equilibrium Risk dominance Satisfaction equilibrium Self-confirming equilibrium Sequential equilibrium Shapley value Strong Nash equilibrium Subgame perfection Trembling hand equilibrium
Strategies	Appeasement Backward induction Bid shading Collusion Cheap talk De-escalation Deterrence Escalation Forward induction Grim trigger Markov strategy Dominant strategies Pure strategy Mixed strategy Strategy-stealing argument Tit for tat
Classes of games	Auction Bargaining problem Global game Intransitive game Mean-field game n-player game Perfect information Large Poisson game Potential game Repeated game Screening game Signaling game Strictly determined game Stochastic game Symmetric game Zero-sum game
Games	Go Chess Infinite chess Checkers All-pay auction Prisoner's dilemma Gift-exchange game Optional prisoner's dilemma Traveler's dilemma Coordination game Chicken Centipede game Lewis signaling game Volunteer's dilemma Dollar auction Battle of the sexes Stag hunt Matching pennies Ultimatum game Electronic mail game Rock paper scissors Pirate game Dictator game Public goods game Blotto game War of attrition El Farol Bar problem Fair division Fair cake-cutting Bertrand competition Cournot competition Stackelberg competition Deadlock Diner's dilemma Guess 2/3 of the average Kuhn poker Nash bargaining game Induction puzzles Trust game Princess and monster game Rendezvous problem
Theorems	Aumann's agreement theorem Folk theorem Minimax theorem Nash's theorem Negamax theorem Purification theorem Revelation principle Sprague–Grundy theorem Zermelo's theorem
Key figures	Albert W. Tucker Amos Tversky Antoine Augustin Cournot Ariel Rubinstein Claude Shannon Daniel Kahneman David K. Levine David M. Kreps Donald B. Gillies Drew Fudenberg Eric Maskin Harold W. Kuhn Herbert Simon Hervé Moulin John Conway Jean Tirole Jean-François Mertens Jennifer Tour Chayes John Harsanyi John Maynard Smith John Nash John von Neumann Kenneth Arrow Kenneth Binmore Leonid Hurwicz Lloyd Shapley Melvin Dresher Merrill M. Flood Olga Bondareva Oskar Morgenstern Paul Milgrom Peyton Young Reinhard Selten Robert Axelrod Robert Aumann Robert B. Wilson Roger Myerson Samuel Bowles Suzanne Scotchmer Thomas Schelling William Vickrey
Miscellaneous	Alpha–beta pruning Bounded rationality Combinatorial game theory Confrontation analysis Coopetition Evolutionary game theory Glossary of game theory List of game theorists List of games in game theory No-win situation Topological game Tragedy of the commons

v t e Gestures
Friendly gestures	Aegyo Air kiss Applause Cheek kiss Dap Elbow bump Eskimo kiss Finger heart Fist bump Forehead kiss Hand heart Handshake Hand wave High five Hongi ILY sign Kiss Liberian snap handshake Lip kiss Namaste OK Pinky swear Pound hug Shaka Thumb signal
Gestures of respect	Adab Añjali Mudrā Bow Canonical digits Curtsy Fist-and-palm Gadaw Genuflection Hand-kiss Hat tip Kowtow Kuji-in Mano Mudra Namaste Ojigi Orans Pranāma Prostration Sampeah Sembah Schwurhand Wai Zolgokh
Salutes	Bellamy salute Nazi salute Raised fist Roman salute Scout sign and salute Three-finger salute (Serbian) Three-finger salute (pro-democracy) Two-finger salute Vulcan salute Wolf salute Zogist salute
Celebratory gestures	Applause Crossed hands Fist pump High five Low five Victory clasp V sign
Finger-counting	Chinese number gestures Chisanbop Finger binary
Obscene gestures	Anasyrma Bras d'honneur Fig sign Middle finger Mooning Mountza Nazi salute Reversed V sign Shocker Sign of the horns Thumb/index-finger ring Wanker
Taunts	Akanbe Loser Talk to the hand
Head motions	Head bobble Head shake Nod
Other gestures	Air quotes Allergic salute Aussie salute Awkward turtle Che vuoi? Crossed fingers Distress signal Duterte fist Eyelid pull Facepalm Finger gun Gang signal Hand-in-waistcoat Hand rubbing Jazz hands Laban sign Merkel-Raute Pointing Pollice verso Shrug Sign of the cross
Related	List of gestures Articulatory gestures Hand signals Manual communication Mudras Nonverbal communication Sign language