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).