Pin (chess)

In chess, a pin is a situation brought on by an attacking piece in which a defending piece cannot move without exposing a more valuable defending piece on its other side to capture by the attacking piece. "To pin" refers to the action of the attacking piece inducing the pin, and the defending piece so restricted is described as pinned.

Only pieces that can move an indefinite number of squares in a horizontal, vertical, or diagonal line, i.e., bishops, rooks and queens, can pin opposing pieces. Kings, knights, and pawns cannot pin. Any piece may be pinned except the king, as the king must be immediately removed from check under all circumstances.

Types

An absolute pin is one where the piece shielded by the pinned piece is the king. In this case it is illegal to move the pinned piece out of the line of attack, as that would place one's king in check. A relative pin is one where the piece shielded by the pinned piece is a piece other than the king, but typically more valuable than the pinned piece. Moving such a pinned piece is legal, but may not be prudent as the shielded piece would then be vulnerable to capture. (See diagram at right.)

Chess

Chess is a two-player board game played on a chessboard, a checkered gameboard with 64 squares arranged in an eight-by-eight grid. Chess is played by millions of people worldwide, both amateurs and professionals.

Each player begins the game with 16 pieces: one king, one queen, two rooks, two knights, two bishops, and eight pawns. Each of the six piece types moves differently. The most powerful piece is the queen and the least powerful piece is the pawn. The objective is to 'checkmate' the opponent's king by placing it under an inescapable threat of capture. To this end, a player's pieces are used to attack and capture the opponent's pieces, while supporting their own. In addition to checkmate, the game can be won by voluntary resignation by the opponent, which typically occurs when too much material is lost, or if checkmate appears unavoidable. A game may also result in a draw in several ways.

Chess is believed to have originated in India, some time before the 7th century; the Indian game of chaturanga is also the likely ancestor of xiangqi and shogi. The pieces took on their current powers in Spain in the late 15th century; the rules were finally standardized in the 19th century.

Chess annotation symbols

When annotating chess games, commentators frequently use widely recognized annotation symbols. Question marks and exclamation points that denote a move as bad or good are ubiquitous in chess literature. Some publications intended for an international audience, such as the Chess Informant have a wide range of additional symbols that transcend language barriers.

The common symbols for evaluating the merits of a move are "??", "?", "?!", "!?", "!", and "!!". In these cases, the corresponding symbol is juxtaposed in the text immediately after the move (e.g. Re7? or Kh1!?, see algebraic chess notation).

Use of these annotation symbols is subjective, as different annotators use the same symbols differently. Moreover, an annotator's use of symbols is often influenced by the player's strength: a positional misjudgment that an annotator might give a "??" if played by a strong grandmaster might pass unremarked if played by a beginner.

Annotators' use of punctuation also may possibly be influenced by the result of the game (regardless of the actual quality of the move); one possible example came in the 11th game of the 1972 World Championship, when Spassky played an unexpected move, 14.Nb1, retreating the knight to its initial square. Spassky won the game, and several annotators gave the move two exclamation points. Edmar Mednis asserted that if Spassky had lost the game, the move would likely have been given two question marks instead.

Computer chess

Computer chess is computer architecture encompassing hardware and software capable of playing chess autonomously without human guidance. Computer chess acts as solo entertainment (allowing players to practice and to better themselves when no sufficiently strong human opponents are available), as aids to chess analysis, for computer chess competitions, and as research to provide insights into human cognition.

Current chess engines are able to defeat even the strongest human players under normal conditions. Whether computation could ever solve chess remains an open question.

Availability

Chess-playing computers are now accessible to the average consumer. From the mid-1970s to the present day, dedicated chess computers have been available for purchase. There are many chess engines such as Stockfish, Crafty, Fruit and GNU Chess that can be downloaded from the Internet for free. These engines are able to play a game that, when run on an up-to-date personal computer, can defeat most master players under tournament conditions. Top programs such as the proprietary Shredder or Fritz or the open source program Stockfish have surpassed even world champion caliber players at blitz and short time controls. In October 2008 Rybka was rated top in the CCRL,CEGT, CSS,SSDF, and WBEC rating lists and has won many recent official computer chess tournaments such as CCT 8 and 9, the 2006 Dutch Open Computer Championship, the 16th IPCCC, and the 15th World Computer Chess Championship. As of February 03, 2016, Stockfish is the top rated chess program on the IPON rating list.

Pin (computer program)

Pin is a platform for creating analysis tools. A pin tool comprises instrumentation, analysis and callback routines. Instrumentation routines are called when code that has not yet been recompiled is about to be run, and enable the insertion of analysis routines. Analysis routines are called when the code associated with them is run. Callback routines are only called when specific conditions are met, or when a certain event has occurred. Pin provides an extensive application programming interface (API) for instrumentation at different abstraction levels, from one instruction to an entire binary module. It also supports callbacks for many events such as library loads, system calls, signals/exceptions and thread creation events.

Pin performs instrumentation by taking control of the program just after it loads into the memory. Then just-in-time recompiles (JIT) small sections of the binary code using pin just before it is ran. New instructions to perform analysis are added to the recompiled code. These new instructions come from the Pintool. A large array of optimization techniques are used to obtain the lowest possible running time and memory use overhead. As of June 2010, Pin's average base overhead is 30 percent (without running a pintool).

Pin (bridge)

In bridge and similar trick-taking games, the term pin refers to the lead of a higher card from one hand to capture a singleton of lower rank in an opponent's hand.

Example

South wants five tricks from this suit. If the opponents' cards split 3-2 and they defend rationally, South must lose at least one trick – dropping a singleton king won't help South. However, if East holds the singleton jack then South can begin by lead the queen and pinning the jack. Provided declarer can re-enter his hand at least once, he can then take up to two finesses to capture the king.

The tactic is also available to the defense, but it is more difficult to find when declarer holds the singleton.

References

Art Angels

Art Angels is the fourth studio album by Canadian singer and songwriter Claire Boucher, professionally known as Grimes. It was digitally released on November 6, 2015 by 4AD, and in physical formats on December 11. Boucher began planning the record in 2013 as the follow-up to her third studio album Visions, however she scrapped most of the material from these sessions and began a new set of recordings in 2014. The track "Realiti", which came from the earlier recordings, was released as a demo in early 2015.

Art Angels has been described as being more accessible than Grimes' previous albums while retaining her experimental influences. The album features guest vocals from Taiwanese rapper Aristophanes and American recording artist Janelle Monáe. Two singles, "Flesh without Blood" and "Scream", were released ahead of the album and a single music video was made for the tracks "Flesh without Blood" and "Life in the Vivid Dream". Art Angels sold 11,000 copies in the first week of its release and became Boucher's highest charting album at the time. The album was released to widespread critical acclaim and was ranked by several publications as one of the best albums of 2015.