Dubov system

Recently, the most used swiss systems in the chess tournaments give priority to the rating and put the color allocation to the second place. This is performed by sorting the players in a score group by their rating and then pairing the top half vs the bottom half (1 vs n/2+1, 2 vs n/2+2, etc...). Let's call the resultant pairing as the natural pairing. After this first procedure the arbiter try to improve the colors.

The consequence of this procedure is that the players in a scoregroup have a quite different ARO (Average Rating Opponent). It means that they are playing different tournaments: one is facing a stronger opponent than another one. So their performance rating will be different although they have the same score. As a result the tiebreak criteria will be almost automatically in favour of the highest rated player. Usually he can win the tournament simply by a quick draw in the last round because all tiebreaks tend to favor him.

This situation is almost the rule in the nowadays swiss tournaments. In fact the pairing system is designed to delay the most important games toward the end of the tournament, but the players "refuse" to play in the last rounds in order to not risk after having defeated weaker players in the first rounds.

This is very unfair from all point of view. From other side the professional players are there not for pleasure but for work, i.e. money and they do not want to risk. This situation is determined even by the pairing system.



The Dubov System

The Dubov system aims to maximise the fair treatment of the players. This is done trying to equalise the average rating of the opponents of the players of a score group. In this manner the players will face in average opponent of the same strength (rating).

In contrast with other swiss system the highest rated player will have no special treatment during the tournament and the eventual tye break will be not automatically in his favour.

When all the players are treated in the same manner the only way for the strongest player to emerge is that to score more points than others.

Moreover the game between strong players may take place in advance and not at the end of the tournament when frequently they accept a draw without to play. Thus such a system in some manner force the players to play each game as very important for the final standing.

From point of view of the arbiter the Dubov system has several advantages: the colour assignation is automatic in that the players are immediately divided in white and black depending by their due colour; the treatment of the standard case is extremely simply with no complicated transposition or exchange to perform; the floaters treatment is easy too. Only the ARO (Average Rating Opponent) calculation is little cumbersome for the arbiter. At the end of round n, the player that met an opponent having rating R will have an ARO equal to

AROc = [AROp * (n-1) + R ] / n

where AROc is the current ARO at round n, AROp is the ARO at previous round n-1, R is the rating of the current opponent. So the preliminary tasks done by an arbiter before to produce a pairing using such a system are the following:

1. Calculate the Average Rating Opponent (ARO) of each player;
2. Determine the due color of each player as in chapter 1 of the FIDE Dubov System;
3. Put each player in a score group according to his score and subgoup according the due color.

For further details please have a look to the appendix B of the Vega's user manual.