Synchronous Chess

Ralf Hansmann, Arnold J. Krasowsky, Andrey Krasowsky

The statistical analysis of the results of the world championship games and other tournaments shows that - apart from draws, in roughly two thirds of all games the white party wins. The two parties have different chances, depending upon the color of the figures. The reason is obviously that the right for the first move gives the white player an advantage. The desire to balance the chances of the players has led A.J. Krasowsky to the idea of removing the source of the unbalance.

For this we suggest to change the article 1.1 of the FIDE chess rules from: "The game of chess is played between two opponents who move their pieces alternately on a square board called a 'chessboard'. The player with the white pieces commences the game. A player is said to 'have the move', when his opponent's move has been made. "

To the Synchronous Chess article 1.1: " The game of chess is played between two opponents. They move their pieces synchronously, and independent of each other (i.e. without previous knowledge of the opponent's simultaneous move).

Thus both opponents make the decision for their move before revealing the own move to their opponent. When both players have decided, which move to make, the moves are mutually announced and implemented on the chess board.

Thereafter, the next turn of synchronous moves only follows directly, if the conditions for an intermediate phase as described below are not given, whereas, when the corresponding conditions are fulfilled, an intermediate phase for exchanging blows takes place, in which the figures that have just been moved can be captured, and these hits can be revenged, and so on (see below). In that latter case, the next turn of synchronous moves begins after the intermediate phase has been finalized.

This alteration of the article 1.1 achieves that the theoretical chances of the two opponents are theoretically absolutely equal. However further modifications of the conventional chess rules are necessary to define, a playable and exciting synchronous chess game. The board, the figures and their starting positions, as well as their fundamental possibilities of movement remain unchanged. However, the changed rules constitute a new form of chess

which we named "Synchronous Chess", considering the timing of the execution of the moves and "Just Chess" which considers the balanced chances of winning.

The authors specified for this play the following changes as compared to conventional chess:

In the FIDE  article 3.1 of the chess rules, one passage, namely: "If a piece moves to a square occupied by an opponent's piece the latter is captured and removed from the chessboard as part of the same move."

Was amended in the Synchronous Chess to: "

"If, in the two synchronous moves of both players ...

a) ... a figure moves on a field, which is occupied by a figure of the opposite color that has not been moved synchronously, then the latter figure is captured and removed from the board. As a result, the hitting figure occupies the field.

b) ... a figure moves on a field, which was before the synchronous moves occupied by a figure of the opposite color, that, however, has been synchronously moved from this field on another field, then both figures safely reach their new position.  Neither of the two figures is removed from the board. Thus, in some cases the synchronous moves can result in a mutual exchange of the positions of the two figures that have been moved (This is possible, even if the ways of their moves overlap with each other).

c) ... both moving figures move to one and the same field, then these figures have both been hit and as a result are removed from the board.

After the synchronous moves of both players, an intermediate phase for capturing the moved figures and a corresponding exchange of blows on one or both of the newly occupied fields takes place, if

d) ... one or both of the moved figures have moved to a field, which was already attacked (or protected) by at least one figure of the opponent before the two synchronous moves took place. In this case, the respective opponent has the right to make an additional move in order to capture the figure that has been moved to the field, which was previously attacked (protected) by him. There is however no obligation to do so. And to capture the figure is only possible, if the player is allowed to make the corresponding move according to the conventional chess rules, when applied to the situation that resulted from the two synchronous moves. In that case, concerning this field an intermediate phase occurs, in which the two players are alternately playing "according to the conventional chess rules", whereby however only the capturing of figures on the respective field is possible. The intermediate phase concerning this field is terminated, as soon as one of the two players is no longer able - or considers it inappropriate - to capture the opponent's figure on that field.

If both partners have the right to make an additional move to capture the opponent's figure on the newly occupied field, then, they have to make their decisions concerning the possible moves independent of each other. The corresponding moves are thus executed synchronously on the chess board (and/or not executed, if a player decides not to capture the respective figure of the opponent). Accordingly, if the intermediate phase for exchanging blows takes place on both fields, then it is played synchronously on these two fields, until it is terminated on one of them. Subsequently it is played on the other field till it is finished there, too. When the intermediate phase for exchanging blows is thus finished, a new turn of synchronous moves of the two players begins.

Moreover, the following rules have been defined for the Synchronous Chess:

A. During an intermediate phase for the exchange of blows, which takes place between two regular turns of synchronous moves, a figure is only allowed to move once.  A figure, which has just been moved in a regular move is however also allowed to move one time during the intermediate phase (if the conditions as defined above apply !).

B. The "en passant" rule does not exist according to our definition of the Synchronous Chess.

C. The king is not allowed to move on a field, which is attacked by a figure of the opponent before the synchronous moves take place. Neither is a player allowed to make a move, which would lead to a position in which the own king is attacked, assuming that the position of the opponent would remain unchanged.

D. If the own king is attacked (i.e., is in a Check ! - position) at the beginning of the synchronous move, then the king is obliged to move to a field which is not attacked beforehand of the execution of both synchronous moves. If there exists no possibility to perform such a move, the player is checkmate as a result of the previous turn of moves.

From these rules the following consequences arise:

1.) A synchronous checkmate position of both players is possible. In this case, the game is terminated with a draw.

2.) It is also possible, that a draw results from a stalemate position of a player.

3. !!!)  Nevertheless, and in contrast to the conventional chess, it is possible that a king is captured directly as consequence of the two synchronous moves. In this case the corresponding party has lost the game.

E. Finally, the Synchronous Chess retains all additional rules of the conventional chess game that define a draw (threefold repetition of the exactly same position, 50 consecutive pairs of moves without the movement of any pawn and without the capture of any piece etc.).

Playing the game

When played without formal time constraints, the only thing to be considered is that the decisions concerning the moves are made independently and synchronously. Thus, both players should covertly note their moves on a sheet of paper, and subsequently, when both moves have been secretly determined and documented, the notes can be uncovered and the corresponding movements can be executed on the board. Thereafter, if the corresponding conditions are given, the intermediate phase for exchanging blows takes place as described above. Then, the next turn of synchronous moves follows.

In the case of a game with formal time constraints, of course, for each player, the time till the own move has been documented on paper is to be counted, exclusively.

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