Swiss System Tournament Project

This is a class project for Intro to Relational Databases. It is not intended for practical use.

A Swiss system tournament is a tournament consisting of two-player matches, such that every player plays in every round, against another player who is adjacent in the standings. This project facilitates a Swiss system tournament by storing player names and match results, displaying standings, and determining which players should meet in each round. Names and results are stored in a database, so they are saved automatically, and persist even if the computer is rebooted.

Prerequisites

To use this software, you must have Python and PostgreSQL on your system.

Installation

Copy all files into a folder.

Suggested usage

Before starting a tournament, be sure you have an even number of players.

You will interact with the database primarily by executing Python functions. Refer to tournament.py to see which arguments should be passed to each function.

I recommend using two command-line windows.

1. Browse to the folder that contains the project files. In the first window, type psql.
2. At the psql prompt, type \i tournament.sql to create the database.
3. In the second window, type python.
4. At the Python prompt, call registerPlayer() once for each player.
5. At the Python prompt, call swissPairings() to see which players should play each other. This function outputs a list of tuples. Each tuple contains the names and IDs of two players.
6. Play the matches output in step 5. For each match, record the results by calling reportMatch() from the Python prompt.
7. If a match is recorded incorrectly, use unreportMatch() to erase it.
8. From the psql prompt, type select * from records; to view the standings. (This is more readable than the output of playerStandings()).
9. Repeat steps 5 through 8 as many times as desired. Note that if you have 2ⁿ players, then after n rounds there will be a single undefeated player. If the number of players is between 2ⁿ and 2ⁿ⁺¹, it may take n or n+1 rounds until there is only one undefeated player.
10. If you wish to reuse the database for another tournament, call deleteMatches() from the Python prompt. This will delete all matches, but keep all players.
11. From the Python prompt, call deletePlayer() for each player that will not be playing in the next tournament, and call registerPlayer() for each new player. Again, make sure you have an even number of players.
12. Go back to step 5.

Limitations

The limitations are due to the structure of the database:

• There is no way to record a match that results in a tie.
• There is no way to deactivate a player who drops out of the tournament early. In order to delete a player from the database, you must also delete all matches that player has played, and that will affect the win-loss records of the remaining players.
• For each match, only the winner and loser is stored; there is no way to store other data such as the date, time, or score of the match.

Nonstandard usage

The software does not enforce the rules of the Swiss system. In particular,

• It is possible to have an odd number of players. In this case, swissPairings() will omit the player who is last in the standings.
• It is possible to start another round (i.e. call swissPairings() again) before recording all matches specified by the last call to swissPairings().
• It is possible to record matches that were not specified by swissPairings().
• It is possible to add or remove players during the tournament.

Ordering the standings

The order of the standings is important, because it determines the pairings. This project orders the standings by number of wins, descending, as specified by the instructor. Players with the same number of wins are order by number of losses, ascending.

Nonstandard usage makes it possible for different players to have very different numbers of matches. For example, Robin could have 3 wins and 7 losses at the same time that Taylor has 2 wins and 0 losses. In this case Robin will appear above Taylor in the standings. This will look strange if you are used to standings that are ordered by win percentage. This problem will not arise if you follow the suggested usage, because the number of matches played by two players will differ by at most 1. In this case, a player with a higher win percentage will always appear higher in the standings.