1. A (=/+]-Position


The following position is from Mark I. Dvoreckij´s book Recognizing Your Opponent´s Resources - Developing Preventive Thinking (Exercise 2-98, D. Gurgenidze).


Diagramm 1


Diagram 1


It is White to move. Oops magnifying glass (5-pieces database!) shows: Remis, i.e. =. But Black threatens to win, i.e. +. Therefore the position is a (=/+)-position, and it is White to move, i.e. (=/+]. If Black could reach this position with the right to move reversed, the position would be of type [=/+), i.e. Black wins!.


Positions of this type are called - don´t worry - Nullzugspositions with advantage for Black. But there is a problem for Black in diagram 1. He can not get the right to move. There is no winnig maneuver as stated in Dvoreckij´s book. Winning maneuver do only exist in won positions, and Black can not win because he can not force White to make an error.


After White´s move


1 Ra3+


- the only not loosing move out of 22 possible moves - Black has to decide where to move his King: b1 or b2. Dvoreckij says 1... Kb1 is an error. But it isn´t. He chooses 1... Kb2, which holds the ballance. After the moves


1...Kb2 2 Rg3 e3 3 Kd5 Kc2 4 Ke4 Kd2 5 Rh3


the position in diagram 2 is reached (the meaning of the colored squares are explained in diagram Color codes for the Representation of Positional Types: There are 9 color codes for positions without taking care of the right to move, and 3 codes - the german traffic light code green-yellow-red for won, remis and lost positions - when taking care of the right to move. All pieces except the white king are thought to be fixed. If you put, for example, the white king in diagram 2 on a green square, black to move wins. The squares marked with a cross are forbidden squares for the white king!):


Diagramm 2


Diagram 2


Diagramm 3


Diagram 3


Farbcode


Color codes for the Representation of Positional Types without taking care of the right to move


Diagram 3: If it is White to move he only can reach a draw with his king on one of the yellow squares. Starting with his king from any other position, for example e4, is lost. If it is Black to move, he can keep no more than balance: The position is of type (-/=), i.e. one sided zugzwang for White. Therefore Dvoreckijs commentary is wrong. There is no reciprocal or mutual zugzwang.


Back to Diagram 1: If White plays


1 Ra3+ Kb2 2 Rh3?


instead of 2 Rg3!, then after


2...e3 (or 2...Kc2) 3 Kd5 Kc2 4 Ke4 Kd2


then we get the same position as in diagram 2, but with White to move (s. diagram 3):


Now Black wins - because he is winning since White´s second move Rh3. Now Dvoreckij remarks:


We should point out that the winning maneuver became possible only because the white rook had to leave the h-file. Bearing in mind the absence of other dangerous ideas for Black, we can come to the conclusion that in the diagram we have a position of mutual zugzwang.


That is not true. It sounds as if Black only has to figure out the correct plan to win: No, White´s move 2 Rh3 is an absolute error and gave Black the chance to win!


Errors in drawn or won positions are always half moves, not plans!


(-/=)


Diagram 4: A zugzwang position for White: (-/=). Farbcode: Pink



Diagram 4 shows the results of diagram 2 and 3 in one diagram. The white king finds himself on e4 in an extraodinary position: White to move is lost, Black to move can hold the balance. The position is of type (-/=), not of type (-/-). In a position with a white king on one of the grey squares we have a (-/+)-position: Black wins whether he has the right to move or not!


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