Rock paper scissors



Rock, Paper, Scissors is a two-person hand game. It is often used as a selection method in a similar way to coin flipping, Odd or Even, throwing dice or drawing straws to randomly select a person for some purpose. Though, unlike truly random selections it can be played with skill if the game extends over many sessions, because one can often recognize and exploit the non-random behaviour of an opponent. It is reported by statisticians that most females and teenagers start with Scissors, while males and adults usually start with rock.

It is also known by many other names such as:Janken (Japan),　Jiandao Shítou Bu (China), Rochambeau, Paper Scissors Stone (UK), Steen, Papier, Schaar (Netherlands),Scissors, Paper, Rock (Australia), Paper Scissors Rock (NZ), Ching Chong Cha (South Africa), Chi Ku Ba (Tamil - India), Even Niyar Umisparayim (Israel), Schnick, Schnack, Schnuck (Germany), Schere, Stein, Papier (Swiss German), Morra Cinese (Italy), Piedra, Papel o Tijeras (Latin America), Kamień, papier, nożyczki (Polish), Pedra, Papel, Tesoura (Portugal), Chin chan pu (Mexico), Ca Chi Pun (Chile), Bao Sing Soum (Cambodia), Sten, sax, påse (Sweden), Pierre, Papier/Feuille, Ciseaux or chifoumi (French), Roche, Papier, Ciseaux (Quebec),  Petra, Psalidi, Charti (Greece) and Kgauwi-bauwi-bo (Korea), Kivi, Paperi, Sakset (Finnish), Pao, Ying, Choop (Thai), Jack en Poy (Philippines), Камень, ножницы, бумага (Russia), Kameň, Papier, Nožnice (Slovak), Kő, papír, olló (Hungarian), Bercus (Brunei), Scissors, Paper, Stone (Singapore).

Various sports may use Rock, Paper, Scissors to determine which team gets the opening play (rather than a coin toss). Similarly, uncertain calls, or even the whole game in case of rain, may be decided by the game. 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 gambling sites as a novelty betting.

Game play
The players both count aloud to three, or speak the name of the game (e.g. "Rock! Paper! Scissors!" or "Reaux! Sham! Beaux!"), each time raising one hand in a fist and swinging it down on the count. On the third count, or on a further beat after the third count, the players change their hands into one of three gestures, which they then "throw" by extending it towards their opponent.


 * Rock: represented by a closed fist.
 * Scissors : represented by the index and middle fingers extended.
 * Paper: represented by an open hand.

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


 * Rock blunts/smashes Scissors: Rock wins.
 * Scissors cut Paper: Scissors wins.
 * Paper wraps Rock: Paper wins.

If both players choose the same gesture, the game is tied and played again.

In some styles of play, the winner of each round "uses" the weapon on the opponent's weapon, to demonstrate that they have won.

Frequently, the game is played in a "best two out of three" match.

Cheating
One of the first tricks learned by a Rock-Paper-Scissors novice is to hold back a throw of paper until the last possible moment to dupe an opponent into believing that one may actually be throwing a rock. Both paper and scissors have this ability; however, unless one is employing a "double-back" strategy, cloaking a paper throw is likely to draw an instinctive paper from one's opponent. If the throw is accidentally revealed too late, that is, not revealed until the thrower's arm breaks the plane where the thrower's arm is perpendicular to the thrower's torso (at a 90 degree angle), this is considered a foul. In such a case the referee will assign a throw of rock, even if this is not what the thrower intended. This is known as a "forced rock."

A common variation on the opening ritual is to have both players hold their hands behind their backs and reveal their already formed throws after the count of three. The intention is to prevent any sort of timing based cheating.

Another way to cheat is to prime three times instead, if the opponent primed twice only, the other could see his opponent's throw without revealing his own, claiming that he thought "I thought we are doing three primes". This form of cheating usually does not get the cheater anywhere, as the round will be most likely replayed. In many cases, participants will bounce three times (while saying "rock, paper, scissors") and then revealing the throw while saying something else (such as "shoot"). Note: 'priming' is the number of bounces one does before revealing the throw.

Variations
There are many different variations of Rock, Paper, Scissors which range from simple changes in the names of the objects to increasing the number of players or objects. While interesting, most rule variations suffer from one problem or another, making them less interesting games. It is sometimes called Paper, Scissors, Stone.

A simple American variation is Pirate, Cowboy, Ninja (Cowboy beating Ninja, Pirate beating Cowboy, Ninja beating Pirate). This version is performed with the players starting standing back to back, taking three paces in opposite directions and then turning and revealing their choice.

Versions of Rock, Paper, Scissors are also observed in many different cultures. It is usually known by direct translations of "Rock, Paper, Scissors" although some cultures have slightly different names or even entirely different elements representing the different objects. For example in Japan there is a variation which uses a tiger, a chief and the chief's mother as the three elements (the tiger beating the chief's mother, the chief beating the tiger and the chief's mother beating the chief). In Indonesia another version is played with the elements as an elephant, a man and an ant (the elephant crushing the man, the man crushing the ant and ant humorously defeating the elephant by crawling into the animal's ear and making it go insane).

In Glasgow, Scotland, the game has also been further developed and is proving very popular amongst the dance community. There are three variants - drum and bass/ballroom dancing/techno. Techno, in which you wave your hands above your head and make techno noises, beats drum and bass. Drum and bass, in which you move your hands down low and make fast drum and bass sounds, beats ballroom. Ballroom, in which you put both arms out in the middle as if waltzing whilst saying 'with you have this dance with me' beats techno. The game has an interesting variant by having no count of 1-2-3-4 between actions, as they merge from one to the other after performing each action for a count of four. A seperate referee is necessary to keep score. Because the game is best to music it is very popular in Glasgow clubs, and certain venues have even held live competitions in which contestants can win free drinks and tickets to select nights.

Malaysians use water instead of paper, and in place of scissors is a bird, made by holding the fingertips together, forming the shape of a beak. The bird drinks up the water, the water sinks the rock, and the rock kills the bird.

The Chinese and Koreans use Cloth along with Rock and Scissors, while the Japanese have adopted Paper. Minor variation is also observed in the standard game play.

The Tamils in India play a variant called Chi-Ku-Ba with slightly different hand formations. Ku is rock formation, held the same; Chi is a scissors with the two fingers closed instead of open; Ba is paper but held vertically with all fingers open like a full hand, with the fingers separated from each other. Chi-Ku-Ba is played with two hands instead of one; after you lose one hand, only the other hand remains in the game. Unlike the rock-scissors-paper rule, there is no asymmetric cycle. One has to play exactly what the other player plays to stay in the game. It is very tough to maintain a draw with two hands, as you get combinations like this, Chi-Chi, Chi-Ku or Ku-Chi, Chi-Ba or Ba-Chi, Ku-Ku, Ku-Ba or Ba-Ku, & Ba-Ba.

Singaporeans play the Indian variant with a slight twist; everything stays the same except that one has to play what the other player did not play. So if the opponent plays Ku-Chi, one have to have Ba-Ku, Ba-Ba, Chi-Ku or Chi-Ba in order to have both hands "alive".

Also the use of another figure in the game is used as a cheat but can only be used when playing under international rules. For example, if a bomb were included in the game, it beats all players but can only be used once in a game of rock paper scissors.

Non-transitivity
Rock, Paper, Scissors is also often used as an example of the mathematical concept of non-transitivity. 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 Rock, Paper, Scissors: 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, Rock-Paper- Scissors could be called "antitransitive" because if A strictly defeats B, and B strictly defeats C, A necessarily loses against C.

Commutativity and non-associativity
Rock, Paper, Scissors also provides an example of a magma that is commutative but not associative, by defining a binary operation on the set {rock, paper, scissors} in which the product of a pair is defined to be the "winner".

Concurrent game (not turn-based)
Rock, Paper, Scissors is also an example of a concurrent game, i.e., one which is not turn-based. In a turn-based game, such as chess, only one player moves at a time. In a concurrent game, all players make their moves at the same time.

Computer play
A large effort has gone into developing successful computer strategies for Reaux Sham Beaux. The results of competition between the different programs is shown at http://chappie.stanford.edu/cgi-bin/roshambot.

Many video games contain an elemental attack and defense system that is very similar to rock-paper-scissors. For example, in Pokemon, a fire-type Pokemon will be stronger against a grass-type, a grass-type will usually beat a water-type, and a water-type Pokemon will almost always defeat a fire-type (in other words, fire>grass, grass>water, water>fire.) RPGs are the most common type of video game to use these rock-paper-scissors inspired battle systems.

Cultural references
Because of its widespread use, Rock Paper Scissors has received substantial references in popular culture. Many television series poke fun at particular characters' incompetence at understanding the game 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. 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.

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. Willing to split up the collection into separate auctions, Hashiyama asked the firms to decide between themselves who would get the 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 Rock, Paper, Scissors, 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 admitted that they treated it as a game of chance and had no particular strategy for the game, but went with "paper".

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

Evolutionary strategy
Biologist Barry Sinervo from the University of California, Santa Cruz has discovered a Rock-Paper-Scissors evolutionary strategy in the mating behaviour of the side-blotched lizard species Uta stansburiana. Males have either orange, blue or yellow throats and each type follows a fixed, heritable mating strategy: This can be summarized as "orange beats blue, blue beats yellow, and yellow beats orange", which is similar to the rules of rock, paper, scissors. The proportion of each male type in a population is similar in the long run, but fluctuates widely in the short term. For periods of 4-5 years, one strategy predominates, after which it declines in frequency as the strategy that manages to exploit its weakness increases. This corresponds to the stable pattern of the game in the replicator dynamics where the dynamical system follows closed orbits around the mixed strategy Nash equilibrium (Sinervo & Lively, 1996; Sinervo, 2001; Alonzo & Sinervo, 2001; Sinervo & Clobert, 2003; Sinervo & Zamudio, 2001).
 * Orange-throated males are strongest and do not form strong pair bonds; instead, they fight blue-throated males for their females. Yellow-throated males, however, manage to snatch females away from them for mating.
 * Blue-throated males are middle-sized and form strong pair bonds. While they are outcompeted by orange-throated males, they can defend against yellow-throated ones.
 * Yellow-throated males are smallest, and their coloration mimics females. Under this disguise, they can approach orange-throated males but not the stronger-bonding blue-throated specimens and mate while the orange-throats are engaged in fights.

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 (Nature. 2002 Jul 11;418(6894):171-4.). 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 antibiotic producing and antibiotic sensitive strains, because antibiotic resistant strains would out-compete the producing strains, providing an environment in which sensitive strains could successfully become established again (Nature. 2004 Mar 25;428(6981):412-4.).

Tournaments
The World RPS Society has been holding the world championships in Canada for the past 5 years. Hundreds of competitors from all over the world come to compete in these championships and during the first 4 years, home grown Canadian talent won the coveted trophy.

The latest winner is Bob 'The Rock' Cooper, from London, UK. He defeated 496 competitors to take the title, winning with a pair of scissors.

Bob is quickly gaining cult status now in the UK, and has his own fansite:

Bob's great popularity has insprired his fans to be petitioning the BBC to re-open the nominations for the Sports Personality of the Year Awards 2006.

WRPS sanctioned tournaments
Starting in 2002, the World Rock Paper Scissors Society (WRPS) standardized a set of rules for international play 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. WRPS events are noted for their large cash prizes, elaborate staging, and colourful competitors. In 2004, the championships were broadcast on the U.S. television network Fox Sports Net.

Professional poker player Phil Gordon conducted what he called "The World Series of Rock-Paper-Scissors" during the 2005 World Series of Poker in which 64 contestants of the WSOP competed in a tournament similar to the NCAA tournament.

Tour events
In addition to the International World Championships the WRPS also endorses or sanctions a year-round series of tournaments world wide. "Endorsed" tournaments agree to abide by the WRPS standardized international rules of play and code of conduct, while "Sanctioned" tournaments will net the winner a trip to compete at the International World Championships. Some of the major events of this tour include:


 * Roshambo Winery RPS Championships, Healdsburg, California
 * RPS Keystone Classic, Philadelphia, Pennsylvania
 * RPS Philadelphia City League Championship Series, Philadelphia, Pennsylvania
 * Rocksdam RPS Charity Tournament, Potsdam, New York
 * Atlantic Yards Smackdown, Brooklyn, New York
 * RPS Australian Championships
 * RPS New Zealand Championships
 * Norwegian RPS Championships

World Series of Roshambo
Professional poker player, Phil Gordon, hosts the annual World Series of Roshambo during the World Series of Poker every year. In 2006, Annie Duke outlasted a field of 64 players who paid $500 each to enter the tournament. First place prize was $10,000. This is the largest buy-in Roshambo event in the world.

USARPS Tournaments
USARPS League is the official Rock Paper Scissors League of the United States. It is sponsored by Bud Light. Matti Leshem is the co-commissioner of the USA Rock Paper Scissors League

In April 2006, the inaugural USA Rock Paper Scissors League 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.

At the first USA Rock Paper Scissors League Championship, Dave "The Drill" McGill defeated Robert "Fast Twitch" Twitchel to win the tournament. In addition, Jason "King of the Morning" Wood won a best-of-500 marathon to earn a brand new car.

The 2007 USARPS Tournament qualifiers are currently underway across America, and the $50,000 national tournament will take place at the Las Vegas Mandalay Bay in May.

National XtremeRPS Competition 2007-2008
The XtremeRPS National Competition is a Nationwide RPS competition with Preliminary Qualifying contests starting in January 2007 and ending in May 2008, followed by regional finals in June and July 2008. The national finals will be held in Des Moines in August 2008, with a chance to win up to $5,000.