DIAGRAM 8

Interposing the Rook on g2 would not help either as the Queen would simply take him at the same time checkmating the King. White's only move is, therefore, to play the King into the corner, and Black then mates by first taking the Knight and then moving the Queen to g2 or h2.

Perpetual Check

If a player is able to check the opposing King continually and he indicates his intention to do so the game is considered a draw.

In the following position, for instance, White on the move can draw the game by giving a perpetual check on e8 and h5. Black cannot help himself as he has to go back and forth with the King on h7 and g8. Without the possibility of this perpetual check White would be lost, for he cannot prevent the Pawn a2 from queening and with two Queens against one Black would easily win as will be seen later from the discussion of elementary endings.

Exchange

To exchange means to capture a hostile man when it allows a man of the same value to be captured by the opponent.

It is rather confusing that the term "exchange" is also used for the difference in value between a Rook and a Bishop or a Knight. To win the exchange, in this sense, means to capture a Rook and to lose for it only a Bishop or a Knight.

Double Pawn

Two Pawns of the same player standing in one file are called a double Pawn. Three Pawns in one file are called a triple Pawn.

Passed Pawn

A Pawn whose advance to the eighth rank is not blocked by an opposing Pawn in the same file and who does not have to pass one on an adjoining file is called a passed Pawn.

Isolated Pawn

A Pawn is called isolated if there are no Pawns of the same player on the adjoining files.

Backward Pawn

A Pawn is called backward if he cannot advance far enough to be protected by fellow Pawns in an adjoining file.

Fork

A Pawn is said to fork two pieces if he attacks them simultaneously.

Minor Piece

The Bishops and the Knights are called minor Pieces as compared with the Rooks and the Queen.

Sacrifice

To sacrifice means to give up a man without obtaining for him a man of the opponent or to give up a man for one of lesser value.

Discovered Check and Double Check

A discovered Check is an attack on the King caused by a man moving out of the line of a piece which he was obstructing. If the man discovering the Check also attacks the King the Check is called a double Check.