# Glossary

**A-square**: Any edge square which is separated from the nearest corner by one other edge square (see Diagram 1-2).

**Anchor**: One or more edge pieces which cannot easily be eliminated by the opposition, offering protection against a wipe-out.

**B-square**: Any edge square which is separated from the nearest corner by two other edge squares (see Diagram 1-2).

**Balanced edge**: An edge occupied by six adjacent discs of the same color, both corners being vacant.

**Blackline**: The diagonal running from h1 to a8.

**Break a diagonal**: Establish a disc on a diagonal controlled by the opponent.

**C-square**: Any edge square which is adjacent to a corner (see Diagram 1-2).

**Control the center**: Having discs bunched in the center of the board while the opponent’s discs are on the outside.

**Diagonal control**: Having a line of several discs of the same color on a diagonal line while the opponent has no discs on the same line.

**Even number theory**: When there is a region with an even number of empty squares, it is usually better to have your opponent initiate play in the region.

**Extract**: Flip an interior disc that was valuable for the opponent.

**Feeding the opponent**: Intentionally giving the opponent options in a region.

**Forced move**: A move on which a player has only one legal play.

**Free move**: A move available to only one player which can be deferred until later in the game and which, when taken, does not create any safe responses for the opponent.

**Frontier disc**: A disc which borders one or more empty squares.

**Gain a tempo**: To achieve an advantage of timing by deriving one more viable move than the opposition from play within a limited area of the board and thereby in effect transferring to the opposition the burden of initiating play elsewhere.

**Hyper even-number theory**: A player can force his opponent to initiate play in an even-numbered region if the player does not have access to any of the squares in the region.

**Interior disc**: A disc which is completely surrounded by other discs.

**Interior sweep**: A strategy by which one side creates a large number of stable interior discs, usually sacrificing edge discs in the process.

**Internal disc**: Same as interior disc.

**Loud move**: A move which creates many new frontier discs.

**Main diagonal**: One of the two eight-square diagonals running between two corners (see Diagram 6-16).

**Pair**: Two empty squares such that if a player moves to one of the squares, his opponent will want to play in the other.

**Parity**: The ability to get the last move in every or almost every region.

**Poison disc**: A disc which turns what would otherwise be a quiet move into a loud move.

**Poisoned move**: A potentially quiet move which is a loud move because of a poison disc.

**Quiet move**: A move which does not create many new frontier discs.

**Run out of moves**: A position in which the player to move has no safe moves available.

**Safe move**: A move which does not concede a corner.

**Semi-forced move**: A move which is forced not by the rules of the game but rather by tactical considerations.

**Stable disc**: A disc which cannot be flipped no matter what moves are made throughout the rest of the game.

**Stoner trap**: A sequence of moves forcing the capture of a corner by first controlling a main diagonal with an X-square move, then attacking a corner so that if the opponent defends the corner, he flips the X-square. See Diagram 9-25.

**Swindle**: A situation where one player gets both moves in a pair because, following the first move into the pair, the opponent does not have a legal move to the other square in the pair.

**Tesuji**: A good move or sequence of moves that can be used in certain frequentlyoccurring positions.

**Unbalanced edge**: An edge occupied by five adjacent discs of the same color, one C-square and both corners being vacant.

**Wall**: A connected group of frontier discs of the same color.

**Wedge**: A disc or line of several discs of the same color on an edge which is abutted on both sides by opposition discs, or playing a move which creates a wedge.

**Whiteline**: The diagonal running from a1 to h8.

**Wing**: An unbalanced edge.

**Wipe-out**: A game which ends with all the discs on the board the same color.

**X-square**: Any square which is diagonally adjacent to a corner (see Diagram 1-2).