In a Swiss System tournament, in most score groups, the number of boards where one player or the other has to receive the "wrong" color can be reduced by making modest changes to the pairings; in a large enough score group (20 or more players), there will almost always be some way to bring that down to the minimum possible problem boards. There will typically be many ways to achieve a given improvement in color allocation, so the question is how to choose among them. Most of this page describes how the US Chess methods work and all references to rules are to those in the US Chess Rule Book. See FIDE Dutch System for a description of that.

 

For each section, in the Add/Edit a Section dialog box, you specify an High/Equalize Rating Limit, and an Low/Alternate Rating Limit for how large a pairing change you are willing to allow to improve colors. The high limit covers the cases where, without changes, some players would receive one color at least two times more than the other. For instance, if two players have had WBW, without a change one will end up with WBWW. The standard high limit is 200. This may seem quite high, but if you fail to correct equalization problems in early rounds, you might run into much more serious problems in later rounds when the score groups are smaller and there are fewer possibilities for color correction.

 

The low limit covers the cases where some players would have the less serious problem of not having color alternation. For instance, WB versus WB means someone gets WBB. The standard low limit is 80. The 80 and 200 point limits are generally appropriate for ratings generated using the Elo methods employed widely in chess.

 

There are two basic types of pairing changes to "correct" colors:

 

Transpositions switch players who are in the same half of a score group

Interchanges switch a pair of players between top and bottom halves

 

Transpositions

 

In evaluating a transposition, WinTD looks at the ratings gap between the two top half players involved and the ratings gap between the two bottom half players and values the change at the minimum of the two gaps. This can sometimes raise questions among the participants, because most players naturally look only at one side (the side opposite them). For example, consider the following situation:

 

1800 WB versus 1570 WB

1600 BW versus 1530 BW

 

The colors on both boards can be corrected by transposition. The 1530 player might be very upset at now playing the 1800 rather than the 1600. But it's only a 40 point change in the bottom half, which is well inside the 80 point limit. The reasoning behind looking at the minimum gap is quite simple: in the "natural" pairings, the 1570 ends up playing the 1800 and the 1530 the 1600 because of the relatively small pre-tournament difference of 40 rating points. The color situation in the current tournament clearly favors the 1800-1530 and 1600-1570 pairings, so we go with those.

 

Interchanges

 

Interchanges are evaluated at the gap between the two players who are switched, which means the lower ranked top half player and the higher ranked bottom half player.

 

Because interchanges "violate" the top half vs. bottom half part of the Swiss System pairing rules, some TD's prefer not to allow them to correct colors. This doesn't conform to current US Chess rules, but WinTD offers you the option with the Avoid Interchanges item in the Color Allocation Rules group in the Pairing Rules tab in the Preferences. This puts the penalty for interchanges high enough that WinTD will not allow them simply to correct colors. You can still end up with an interchange to fix a more serious problem (duplicate pairing or teammate conflict, for instance).

 

A second preference item, Limit Interchanges, can also be used to discourage interchanges. With Limit Interchanges, an interchange will not be used to fix an alternation problem, though it can be used for fixing equalization. We think this is closer to what TD's would do in practice. The standard treatment of interchanges (that is, if you don't choose either Avoid Interchanges or Limit Interchanges) is to use an interchange only if there is no adequate transposition below the low limit.

 

What WinTD Does

 

In a large score group, WinTD is likely to find a way to correct colors which is a bit more complex than a few transpositions. For instance, in the following situation:

 

1800 W versus 1500 W

1780 B versus 1480 W

1760 B versus 1460 W

1730 B versus 1400 B

 

one way to correct the colors would be to switch the 1500 and 1400. This is a 70 point change in the top half and a 100 point change in the bottom. But another way to do this is to pair 1800-1400, 1780-1500, 1760-1480, 1730-1460. This cuts down on the number of players who have very large changes in the ratings of their opponents. Instead of switching the 1500 and 1400, this puts the 1400 at the top and pushes everyone else down a slot. WinTD evaluates the pairing changes by looking at the boards as now paired and taking the minimum of the gap between the new opponent and the natural opponent. For instance, the 1800-1400 is evaluated at 70 (1800-1730=70, 1500-1400=100), the 1780-1500 at 20 (1800-1780=20, 1500-1480=20), etc.

 

Swaps Involving Unrateds

 

The rule book unfortunately does not indicate how to value changes involving unrated players. As default behavior, WinTD values a switch of a rated with an unrated at 1/2 the lower limit. This means that a swap involving a rated and an unrated will always be acceptable, though it will not be chosen over a swap between two unrateds or between two rated players who have ratings very close together. For instance, in the following situation

 

1800 WB versus 1500 WB

1730 BW versus 1400 BW

1600 WB versus nnnn WB

 

the preferred correction is to switch the 1400 and the unrated. While this is probably correct technically (the rule book does indicate, in effect, that swaps to and from unrateds should always be acceptable), we have provided a preference item Avoid Swap w/ Unrated in the Color Allocation group if you don't agree. If you choose this, WinTD will value a swap to or from an unrated only on the other side. Thus, in this example the 1400-unrated switch would be evaluated at 130 (the difference on the top half) while the 1400-1500 switch would be evaluated at 70 (the minimum of 1800-1730 and 1500-1400).

 

Three in a Row

 

The preference item Avoid Three in a Row conforms with Rule 29J6. With this turned on, WinTD will do anything it can to avoid giving one player a color three times in a row, short of dropping extra players out of their score group. The only exception to this is where the player needs three in a row in order to equalize colors. For instance, WWBWWBB still needs another Black in order to get to four of each color.

 

Copyright © 2026 Thomas Doan