Extended Sonneborn-Berger for Teams

Extended Sonneborn-Berger for Teams, abbreviated ESB, rewards points earned against teams that finish strongly. In team competition, Match Points or MP represent winning, drawing, or losing the overall match, while Game Points or GP add the individual board results.

ESB is not one fixed formula. For every opponent, one measure of that opponent's final score is multiplied by one measure of what the tied team scored against it. The contributions are then added. The regulations provide four combinations:

• EMMSB: opponent's final MP multiplied by MP scored against that opponent.
• EMGSB: opponent's final MP multiplied by GP scored against that opponent.
• EGMSB: opponent's final GP multiplied by MP scored against that opponent.
• EGGSB: opponent's final GP multiplied by GP scored against that opponent.

A competition may choose one variant or combine several in a published order. Under the current rules of FIDE, the International Chess Federation, each ESB calculation also excludes the contribution associated with the opponent having the lowest MP in variants using opponent MP, or the lowest GP in variants using opponent GP. If several opponents share that minimum, the lowest contribution among them is removed.

ESB measures the quality of results through opponents' final strength. It differs from EDE, which first concentrates on matches played inside the tied group.