A

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

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

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.

D

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.

E

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.

F

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.

G

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.

H

Hyper even nuber 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.

I

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.

L

Loude move

A move which creates many new frontier discs.

M

Main diagonal

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

P

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.

Q

Quiet move

A move which does not create many new frontier discs.

R

Run out of moves

A position in which the player to move has no safe moves available.

S

Save 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.

T

Tetsuji

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

U

Unbalanced edge

An edge occupied by five adjacent discs of the same color, one Csquare and both corners being vacant.

W

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

X-square

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

"Othello: A Minute to Learn...A Lifetime to Master" by Brian Rose © 2005