Tie-breaking in Swiss system tournaments

Tie-break systems are used in chess Swiss system tournaments to break ties between players who have the same total number of points after the last round. If the players are still tied after one tie-break system is used, another system is used, and so on, until the tie is broken. Most of the methods are numerical methods based on the games that have already been played or other objective factors, while some methods require additional games to be played, etc. The idea behind the methods based on the games already played is that the player that played the harder competition to achieve the same number of points should be ranked higher.

Harry Golombek points out deficiencies in most of the tie-break systems and recommends a playoff if there is time. If not, he recommends Sonneborn-Berger and then the player who has the most wins. For Swiss tournaments, he recommends the Buchholz system and the Cumulative system harvcol|Golombek|1977|p=322.

Median

The Median system is also known as the "Harkness System", after its inventor Kenneth Harkness. For each player, this system sums the number of points earned by the player's opponents, but discarding the highest and lowest. If there are nine or more rounds, the top two and bottom two scores are discarded. Unplayed games by the opponents count ½ point. Unplayed games by the player count zero points. This is also known as the Median-Buchholz System harvcol|Just|Burg|2003|pp=199-200.

Modified Median

The Modified Median system is similar to the Median system, except:
* Players with exactly 50 percent score are handled as in the regular Median system
* Players with more than 50 percent score have only their lowest-scoring opponent's score discarded
* Players with less than 50 percent score have only their highest-scoring opponent's score discarded harvcol|Just|Burg|2003|pp=199-200.

olkoff

This system is the same as the Median system, except that no scores are discarded harvcol|Just|Burg|2003|p=200. Ephraim Solkoff did not invent this system. He introduced it to the United States in 1950, but it was used in England prior to that harvcol|Harkness|1967|p=138.

Cumulative

To calculate this, sum the running score for each round. For example, if a player has (in order) a win, loss, win, draw, and a loss; his round-by-round score will be 1, 1, 2, 2½, 2½. The sum of these numbers is 9. This system places more weight on games won in the early rounds and the least weight on games won in the final rounds. The rationale for this system is that a player who scored well early in the tournament has most likely faced tougher opponents in later rounds and should therefore be favored over a player who scored poorly in the start before subsequently scoring points against weaker opponents harvcol|Just|Burg|2003|pp=200-201.

Cumulative opponent's score

This sums the cumulative scores of the player's opponents harvcol|Just|Burg|2003|p=202.

Result between tied players

If the tied players played each other, if one of them won then he finishes higher on tie-break harvcol|Just|Burg|2003|p=201.

Most games with the black pieces

The player that had the black pieces the most times finishes highest on tie-breaks harvcol|Just|Burg|2003|p=201.

Kashdan

Invented by Isaac Kashdan, this system awards four points for a win, two for a draw, one for a loss, and zero for an unplayed game. If players with no unplayed games tie, the one with fewer draws finishes higher on the tie-break (i.e. a win and a loss is better than two draws) harvcol|Just|Burg|2003|p=201.

onneborn-Berger (Neustadtl score)

Add the scores of every opponent the player beats and half of the score of every opponent the player draws harvcol|Just|Burg|2003|p=201. The system was named after William Sonneborn and Johann Berger, but it was invented by Oscar Gelbfuhs harvcol|Harkness|1967|p=137. The system is the main tie-breaking system in round robin tournaments, but is also used in Swiss tournaments. It is also called the Neustadtl score.

History of the Sonneborn-Berger system

What we call the Sonneborn-Berger system was not invented by Sonneborn or Berger, and it was not originally designed for tie-breaking. It was invented by Oscar Gelbfuhs about 1873 to be used as a weighted score in round-robin tournaments. It would be used instead of the raw score for final places. In 1886 Sonneborn criticized the system and suggested an improvement that would give a better weighted score. His suggestion was to add the square of the player's points to the amount calculated as above. In 1887 and 1888 Berger studied Gelbfuhs' system and the suggestion of Sonneborn. This improvement became known as the Sonneborn-Berger system.

When the system is used to break ties between equally-scoring players, adding in the square of the player's raw score does no good, so the Sonneborn improvement is omitted. However, the system has retained the Sonneborn-Berger name harvcol|Harkness|1967|pp=136-37.

Opponent's performance

This method uses the average performance rating of the player's opponents. The "performance rating" of a player is basically the rating he would receive if he had started the tournament without a rating harvcol|Just|Burg|2003|p=202.

Average rating of opposition

The average rating of the player's opponents harvcol|Just|Burg|2003|p=202.

Time of Loss

Among tied players, the player whose first loss came last gets priority.If player A’s first loss was in round 4 and player B’s first loss was in round 2, player A gets priority. This was a tiebreaker used by POP in 2004-2005.

Tardiness

If a player arrives after the first round is paired, the player loses priority. This tiebreaker is currently used by POP.

peed play-off games

The tie is broken by one or more games played with fast time control, or Fast chess.

ingle fast game

FIDE rules provide for a single fast decisive game. Black gets five minutes on the clock whereas White gets six minutes but must win (i.e. a draw counts as a win for Black). The player who wins the draw of lots may choose which color he wants.

Coin flip

As a last resort, ties are broken by a random process such as a coin flip harvcol|Just|Burg|2003|p=203.

USCF recommended order

The U.S. Chess Federation (USCF) recommends these as the first four to be used: harvcol|Just|Burg|2003|p=199
# Modified Median
# Solkoff
# Cumulative
# Cumulative opponent's score. The USCF recommends having a comprehensive list of the systems to be used in order, such as this one used by a state organization:
# Modified Median
# Solkoff
# Cumulative
# Result between players
# Most games with the black pieces
# Kashdan
# Sonneborn-Berger
# Coin flip.

ee also

* Tiebreaker

References

* Citation
surname1=Golombek|given1=Harry|authorlink1=Harry Golombek
title=Golombek's Encyclopedia of Chess
year=1977
publisher=Crown
ID=ISBN 0-517-53146-1
* Citation
surname1=Harkness|given1=Kenneth|authorlink1=Kenneth Harkness
title=Official Chess Handbook
year=1967
publisher=McKay
* citation
last1=Hooper | first1=David | author1-link=David Vincent Hooper
last2=Whyld | first2=Kenneth | author2-link=Kenneth Whyld
year=1992 | title=The Oxford Companion to Chess | edition=second
publisher=Oxford University Press
isbn=0-19-280049-3
*Citation
surname1=Just|given1=Tim
surname2=Burg|given2=Daniel B.
year=2003
title=U.S. Chess Federation's Official Rules of Chess
edition=fifth
publisher=McKay
ID=ISBN 0-8129-3559-4