EGF Official ratings system

• The event took place not earlier than January 1, 1996.
• The tournament is recognized as EGF classified event.
• Both handicap and even games are accepted.

The rating list includes all "European" players who participated at tournaments that are in the database. An average 1 dan should have Go Rating about 2100 and the difference between grades is set to 100 (6 dan = 2600, 1 kyu = 2000, 20 kyu = 100 etc.). These values are also used to initialize the rating of a new player. The scale of professional grades is set provisionally to 1p = 7d = 2700, 2p = 2730, ... , 9p = 2940. If player's rating drops below 100, it is reset to GoR=100 which is fixed as the bottom value.

Example 1: The ratings of top European amateur players Guo Juan and Lee Hyuk fall in the region of 3p-4p.

Example 2: The player with GoR = 2050 can be regarded as either a weak 1d or a strong 1k.

Depending on players' tournament results and on the various ranking systems used in different countries, the correspondence between grades and GoR may not work quite well especially for lower kyu grades. However, it gives a relatively good measure of player's strength provided that he/she has participated in at least 3-5 tournaments.

If a player has not participated at any considered tournament for some time (this period is set to 2 years for dan players, 12 months for 1-10 kyu, and 6 months for 11-20 kyu; the actual year/month is not counted), he/she drops out from the current rating list. However, the player's rating is kept in the database of players and it is used once he/she appears again at any tournament in the future.

The rating system is derived from ELO rating system used by International Chess Federation (FIDE). It is based on the idea that one can define a probability of winning a game (so called winning expectancy S_E) depending on the difference of opponents ratings D=R_B-R_A. For the player with lower rating (let us call him "player A") the quantity is given by

(1)      S_E(A) = 1 / [e^D/a + 1] - ε/2

The winning expectancy of his higher (or evenly) ranked opponent ("player B") is obtained from the equation

(2)      S_E(A) + S_E(B) = 1 - ε

If ε=0, Eq.(2) simply states that the sum of both winning expectancies should be normalized to one. However, such setting suffers from long term deflation as the new improving players take points from already established players. This is countered by various instruments like an existence of rating bottom, winning expectancy setting, rating resets in some specific cases and finally by introduction of a small parameter ε > 0.
At the moment, we use ε=0.016, a value fitted to balance rating variations in dan region. Although such small value has negligible effect on variation of player's rating at one tournament, the parameter ε allows to tune the long term system behaviour in a desired way.

A typical behaviour of S_E is shown in Table I where the quantity was calculated with the parameters fixed at the values: a=115, ε=0. This setting gives about 30% probability for beating a 1 grade stronger opponent. Since stronger players play more consistently than the weaker ones, the probability of beating a 1 grade weaker opponent tends to rise with player's grade. This fact is reflected in our system by an appropriate dependence of parameter a on the rating value of player A. The complete setting is shown in Table II where the corresponding probabilities of beating a 1 grade stronger opponent are given as well. As one can see, 20 kyu is expected to win about 40% games with one grade stronger opponent while the top amateur players should win only 20% of their games with 100 rating points stronger opponents.

In a single even game the rating of a player changes by

(3)      R_new - R_old = con * [ S_A - S_E(D)]

where S_A is the achieved result (S_A = 1, 0 or 0.5 in case of jigo) and the factor con characterizes the magnitude of the change. In our system the parameter con is a decreasing function of player's rating specified in Table II.

All the following examples are computed with ε set at zero:

Example 3: Both opponents have the same rating R_A=R_B=2400. This gives D=0 and S_E=0.5 for both players. If player A wins, his new rating will be

  R_new(A) = 2400 + 15 (1-0.5) = 2407.5

At the same time, the rating of player B drops by 7.5, i.e. R_new(B)=2392.5

Example 4:   R_A=320, R_B=400 and player A wins:

  a=189,    S_E(80)=0.396

  R_new(A) = 320 + 104 (1-0.396) = 383

  R_new(B) = 400 + 100 (0-0.604) = 340

The system also allows to include handicap games assuming that the rating difference D is reduced by 100(H-0.5), where H is the number of given handicaps. Note, that it can happen that the winning expectancy of a weaker player is larger than S_E of the stronger player (i.e. the weaker player is expected to win the game) if the number of given handicaps (reduced by 0.5) is larger than the absolute value of (R_A-R_B)/100.

Example 5:   R_A=1850, R_B=2400, player A takes 5 handicaps and wins:

  D=100,    a=90,    S_E(100)=0.248

  R_new(A) = 1850 + 33 (1-0.248) = 1875

  R_new(B) = 2400 + 15 (0-0.752) = 2389

The post-tournament ratings are calculated assuming that every player enters the games with all opponents at the same initial (pre-tournament) rating. It means that the ratings are not reevaluated after each game (round) and the "new" ratings are computed from the "old" ones adding all contributions from the games the player completed at a given tournament. In other words, we assume that the ratings of players do not change in the process of one tournament.

If a rank professed by the player had improved significantly (at least by 2 grades for amateur players or by 1 professional grade) with respect to the highest previously professed rank, the rating of the player is reset. This measure helps to deal with fast improving players and with players who participate at included tournaments only occasionally. To avoid undesirable oscillations in the bottom part of the rating list the drop of player's rating at one tournament is restricted to 100 points.

The work on the program that calculates the ratings is still in process. In the future, the program should also be used for some statistical purposes and for the maintenance of the database of go players. We welcome any comments and suggestions.

Acknowledgement:

The rating system has been tested, with permission, on the database of professional games provided with the GoGoD Encyclopaedia CD produced by J. Fairbairn and T.M. Hall. We thank R. Kok and Ch. Gerlach for providing us with their databases of tournament results and A. Engels for maintaining a web page which helped us immensely to collect the tournament data. We would also like to thank J.-L.Gailly for advising us on the correct treatment of handicap games. Finally, we acknowledge a help of many people who have contributed with their comments and suggestions, and especially of those who have kept us informed by sending new tournament results.

The results must be submitted through the online parser which is present in the backend section of this website.
In order to be allowed to submit data, you will be requested to register a user account.
If you encounter any problems, report them to egd@europeangodatabase.eu

When the results are sent we need to know:

• the name of the event
• the place (city) where it was hold
• the exact date of the event
• tournament class (or the time limit including byoyomi)
• handicap strategies (if any handicap games occured)

1. Adjusted time (TA) is calculated as
             TA = basic time + time equivalent to 45 (60) moves in standard (Canadian) byoyomi.
   Sudden death - implying adjusted time = basic time - is acceptable, provided all other criteria are met.

2. As of October 2010 the Rating Commission has approved the inclusion of tournaments played with the Fischer timing system. These are the rules for classify such tournaments:
   TA = basic time (BT) + bonus calculated for 120 moves
   
   • Class A: minimum BT 45 minutes, minimum TA 75 minutes (e.g.: 45 minutes + 15'' per move)
   • Class B and D: minimum BT 30 minutes, minimum TA 50 minutes (e.g.: 30 minutes + 10'' per move)
   • Class C: minimum BT 20 minutes, minimum TA 30 minutes (e.g.: 20 minutes + 5'' per move)

The EGF Ratings Committee reserves the right to adjust the class of a tournament if considered necessary. The class of the event should be known before it is held. The organizer may demote the class in tournament announcement if the lower class suits better to his intentions (e.g. when new tournament system or rules are tested). The events that do not meet the specifications mentioned above are not recognized as classified EGF tournaments.

        <opponent's place><symbol>[/<colour>[<h>]] 
where 
        <symbol> is + (a win), - (a loss) or = (jigo)
        <colour> means the colour of stones ('b/w' = black/white)
          <h>    specifies the number of given handicaps
   
Examples: 35=, 23+/w (equivalent to 23+/w0), 11-/b5 

        0+  a free win
        0-  a free round
        0=  a free round (0.5 added to the score and MM)

• AGAGD, the AGA Go Database
• AGA Rating system
• French go rating system
• Brief description of ELO system
• ELO ratings used by FIDE