Competition systems: “Swiss system”

Competition Algorithm

It is desirable that an even number of players participate in the competition, but an odd number is also allowed. All participants are divided into two equal groups either by rating (group of strong and group of weak), or by lot.

In the 1st round, the pairs of opponents are divided according to the principle: the strongest from the first group versus the strongest from the second, second strongest from the first group versus the second strongest from the second, etc. (In the table, each pair of opponents is highlighted in either black or blue). If, for example, there are 32 participants in the tournament, then the first (by rating) plays from the 17th, the second from the 18th, etc. With an odd number of players, the player with the last number gets a point in the 1st circle without a game (in the table the participant at number 17).

In the following circles, all participants are divided into groups in which participants usually have the same number of points scored. The table in bold indicates the numbers of the participants who won their matches. So, after the 1st round, there will be two groups: with 1 point (winners) and with 0 points (losers). If the group contains an odd number of players, then one player is transferred to the next lower scoring group (in the table the participant is numbered 17).

Pairs of rivals for the next round are made up of one point group according to the same as in the 1st round, rating principle: the best player from the upper half of the group whenever possible meets the best player from the lower half of this group. But it is not allowed that the same participants meet more than once.

Seats in the tournament are distributed according to the number of points scored. Places for participants with the same number of points are usually allocated:

according to the progress coefficient – a higher place is given to a player who, during the course of the tournament, stayed longer in a higher place (occupied places in each circle are calculated).
by Buchholz coefficient, which is defined as the sum of points scored by all rivals of a given player in a tournament;
according to the average rating of rivals. Therefore, those who have rivals with a higher average rating are awarded a higher place.
Advantages of the system:

the selection of pairs in each circle is organized in such a way as to ensure a reliable distribution of places in accordance with the points accumulated;
when a rating is not applied or does not exist, it has advantages over the Olympic system and its variants. Even completely random seeding (draw) in the spectacle group (taking into account the restrictions on the non-repeatability of pairs) does not matter much. The participant, if in the first rounds loses the strongest, then continues to play and can gain points. This is especially important in tournaments with the participation of players of various levels, in which the weakest obviously do not get to the first places, but gain tournament experience;
in each circle (except for the first: one or two) there are players of approximately equal strength, moreover, it provides a significant improvement in the position in the tournament, and defeat sensitively lowers the player down. This creates a tense and interesting fight;
no groups, nets, first and second finals.
Disadvantages:

the winner, winners and outsiders are determined, but in the middle of the tournament table there is no clear distribution of seats;
sometimes it happens that two winners with the same number of points did not meet each other during the tournament. The winner must be determined by additional factors, which, of course, is not as interesting as the final match of applicants in other systems;
the actual implementation is quite complicated, which requires either the use of a computer program or a very experienced judge. In the latter case, as a rule, errors are inevitable. True, they do not greatly affect the final result;
in the case of a computer implementation of the system, in case of failure of one or several participants, you have to make pairs manually, which also requires more experience. In the Swiss system, it is impossible to act as a round robin, where the result of a retired player is canceled if he played less than half of the prescribed circles, and otherwise, a point is awarded to those with whom he has not played. That is, it is impossible to cancel the results of previous matches, because in this case, some participants will lose one game.
with an odd number of participants in each round, one technical victory is awarded (though having the least number of points);
participants cannot predict who they will meet in the following circles, as is possible in varieties of the Olympic system.