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TwinFeats Simple Swiss Pairing Engine - TDX

Updated September 20, 2005, v1.8

Section combining bug fixed
Fixed bug in BYE not being undone when using Undo Pairings
Withdrawn players no longer are included in Round Pairing printouts
Assigning a player a forfeit loss now withdraws the player automatically
Player grade levels can now be entered on the registration page for easier award assignments

TDX v1.8 is now available! This simple application should suffice for most small to medium chess tournaments. Features include:

Multiple player databases, including USCF supplement imports
Up to 10 sections per tournament
Any number of players per section
Prints crosstables, wallcharts, and round pairing sheets
Imports USCF dbase3 files, or USCF tab-delimited files
Manual pairing override
Exports USCF DBase3 files for tournament reports

Description of pairing algorithm

TDX follows the basic Swiss-system pairing rules, and tries to adhere to the core 5th edition USCF Swiss-system pairing rules as well. In each round, players are divided into "score-groups" based on their standing in the tournament. Score groups are then split into two halves, the top half and the bottom half. Players are considered for pairing, in rating order, from the top half against the corresponding player in the bottom half, according to these rules:

Players must not have already played in a prior round
Players cannot be on the same team
Both players must not have had the same color in the previous two rounds
Both players must not have had the same color two times more than the other color

If any of the rules indicates the players cannot be paired, then the next lower person in the scoregroup is considered for pairing. If all players in the bottom half of the score group have been tried, then start with the bottom player in the top half of the score group and work backwards. If the current player cannot be paired, then ignore rule 4 (if configured to do so) and repeat the pairing process. If still no pairings possible, ignore rule 3 (if configured to do so) and repeat the pairing process. If still no pairings possible, ignore rule 2 (if configured to do so) and repeat the pairing process. If still no pairings possible, the current player must be moved to the next lower score group.