# Deduction (chess)

A deduction in the game of chess is a move of a piece by which it steps out of the line of action of a long-stepped piece (bishop, tower, queen), which indirectly activates it and makes an attack. Often a trigger is used to realize a double attack . The trigger is an important element of chess tactics .

## Trigger chess

A special form of the trigger is the trigger chess, in which an indirectly activated piece offers chess. Since this chess command must be parried, the withdrawing piece has a wider range of movement than with a normal move, since an additional attack originating from it cannot usually be countered in the next move. The result is an effect as if the withdrawing figure is allowed to make two successive moves. This gives every trigger a high level of penetration. The pulling stone is also referred to in chess jargon as a desperado , as it can behave “lawlessly” if the withdrawal threat is strong enough.

The case in which the moved piece offers check, while another, long-stepped piece activated by the move poses a secondary threat, has a similar effect.

## Demonstration of a trigger chess

 a b c d e f G H 8th 8th 7th 7th 6th 6th 5 5 4th 4th 3 3 2 2 1 1 a b c d e f G H

Diagram 1: The lady is threatened.

White to move: If the rook moves, the bishop offers check to the black king . Therefore, the rook can move to the squares a7 or f5 controlled by the queen and attack the black queen with impunity. After a king move, the rook captures the queen on a5. Black could also move Qd5, but then the bishop simply captures the queen. With a suitable rook deduction, the queen is inevitably lost.

Black to move: The impending loss of queens can only be prevented by avoiding the check with the move Kh8. Even a checkmate by the queen on the first row is parried by the deduction chess Rf1 +. Without the white pawn on b3, the queen would have three more parades on the threat by attacking the bishop with Qa4, Qb4 or Qc3. An attack on the bishop by Qc5, on the other hand, would also lead to the loss of the queen due to the answer Rc7 +.

## opening

Some opening traps are associated with a withdrawal chess. An example is the variant of the Russian Defense :

 a b c d e f G H 8th 8th 7th 7th 6th 6th 5 5 4th 4th 3 3 2 2 1 1 a b c d e f G H

Diagram 3: Black to move.

After the moves
1. e2 – e4 e7 – e5
2. Ng1 – f3 Ng8 – f6
3. Nf3xe5 Nf6xe4? (better d7 – d6)
4. Qd1 – e2 Ne4 – f6 ?? (better Qd8 – e7)
5. Ne5 – c6 +

White offers chess through the queen, at the same time the white knight attacks the black queen. The lady is lost.

## Double chess

If in a withdrawal chess the withdrawing piece also offers chess, then one speaks of a double chess . Since in this case there is a check from two directions, the threatened king must move. The chess commandments cannot be fended off in any other way. The double chess often plays a decisive role in combinations to the suffocated mate . The " en passant capture" gives another interesting possibility to create a double chess.

Here are two examples of double chess that came about through a queen sacrifice :

## Dilemma

In rare cases, you can cause a dilemma with the withdrawal check. An example can be found in the article about Hans Peter Rehm .

## battery

In chess composition , the constellation in which one side can give a withdrawal chess is called a battery .