Famous quotes

"Happiness can be defined, in part at least, as the fruit of the desire and ability to sacrifice what we want now for what we want eventually" - Stephen Covey

Friday, May 25, 2012

A really weird Soccer Match

Another great post by Presh Talwalkar on a really weird soccer match where both the teams used Game Theory

Yesterday I wrote about a weird World Cup game where nobody tried to score.
There is amazingly an even weirder game on record. The infamous game is about a team advancing in a tournament by scoring an own goal.
In the 1994 Shell Caribbean Cup, Barbados needed two clear goals to advance against Grenada. Losing or winning by one goal meant not advancing. The wrinkle was a rule that goals in overtime would count double to reward a team winning a close game.
The stage was set for an unusual match. Professor Mike Shor of Vanderbilt University writes about the resulting craziness where scoring an own goal was rational:
Barbados needed to win by two goals. With less than ten minutes left in the match, Barbados led by exactly two goals and began to play very defensively. In the 83rd minute, Grenada finally scored, making the score 2-1. Barbados tried to answer but, with only three minutes remaining, was unable to score. Members of the Barbados team contemplated their options. To advance, they needed either to score one more goal in the last three minutes (winning by two), or force the game to extra time where a goal would count as if they won by two. Barbados scored on their own net, tying the game at 2-2.
This is not yet the odd part of the match. The Grenada players, initial shock abating, developed their own strategy. If they could score on Barbados in the waning minutes, they would win the match and advance. But, if they could score a goal on themselves, they would lose by one goal which was still enough to advance. For two minutes, Grenada tried to score on either goal, with Barbados players split between defending their own goal and that of their opponents!
Normal time ended in a tie and the game did go to overtime, in which Barbados scored a game winner and advanced
[emphasis mine]
Professor Shor’s cleverly dubbed the game “which goal is mine.”
Barbados managed to advance but it was eliminated in the next round. No penalties were given to either team since they were both trying to win (albeit in an odd way akin to the puzzle about fixing a broken bet).
The lesson is that simple and seemingly smart rules can have a devastating impact on competition and good play. And much of this can be anticipated if one uses game theory to consider the incentives by thinking ahead and reasoning backwards.
There is a video which shows highlights and the own goal (sadly it omits the chaos where Grenada tried to score on either goal)

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