Since the soccer server provides a challenging environment,
the
intentions of the players cannot mechanically be deduced, there is a
need for a referee when playing a match. The included artificial
referee is only partially implemented and can detect trivial
situations,
when a team scores. However, there are several
hard-to-detect situations in the soccer server,
deadlocks, which
brings the need for a human referee. All participating teams are also
obliged to play according to a gentlemen's agreement,
not to use
loopholes.
Since the first version of the soccer server was completed in 1995, there have been four world cups and one pre-world cup event, not to mention all other RoboCup-related events. The 1996 pre-RoboCup event [#!PreRoboCup96-proceedings!#] was held in Osaka, with only seven entrants in the competition which ended with a Japanese victory by the team Ogalets from Tokyo University. In Nagoya the following year, the first formal competition was held in conjunction with the IJCAI'97 conference. The competition had 29 teams participating, and the winner was AT Humboldt [#!burkhard1997:athumboldt!#]. The RoboCup world cup of 1998 was played in conjunction with the human world cup in Paris, and the winning team was CMUnited98 [#!stone1998:td!#]. During the world cup, media was heavily covering the event, as it was public in a museum in the suburbs of Paris. The year after, the world cup was held in conjunction with IJCAI'99 in Stockholm, and the winners (once again) were CMUnited99 [#!stone1999:td!#]. An unchanged version of the champion team must participate, as a benchmark, in the next world cup. The benchmarking teams have always been able to win their group, but only in 2000 did the benchmark team advance further than the first game after group play.