If it were Black’s move he would easily win.  In fact he has two different ways of checkmating White in three moves.  One of them would be to take the Knight with the Rook, attacking the King and forcing White’s Rook to recapture as the King has no square to go to; then to give check with the Queen on g3 forcing White’s King to h1 and enabling the mate with the Queen on g2 or h2.

The other way would be to start with the check on g3.  As White’s Knight is pinned he cannot capture the Queen.

+---------------------------------------+
8 |    |    |    |    |    |    | #K |    |
|---------------------------------------|
7 |    |    |    |    |    |    | #P |    |
|---------------------------------------|
6 |    |    |    |    |    |    |    |    |
|---------------------------------------|
5 |    |    |    |    |    |    |    |    |
|---------------------------------------|
4 |    |    |    |    | ^Q |    |    |    |
|---------------------------------------|
3 |    | #Q |    |    |    |    | ^P |    |
|---------------------------------------|
2 | #P |    |    |    |    |    |    | ^P |
|---------------------------------------|
1 |    |    |    |    |    |    |    | ^K |
+---------------------------------------+
a    b    c    d    e    f    g    h

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.