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Introduction

Premium Chess introduces a rating system for rated chess games played in Premium Chess Online Arena playing zone between Arena full members. The rating system calculates ratings depending on the time control of a rated game. Therefore, a full Arena member may acquire three different ratings for rapid, blitz and bullet activity.

How to obtain the Official Rating

To obtain an official rating a player must be owner of a valid membership and complete a sequence of official games:

  1. player must complete at least 5 official games (i.e. games in one of the official time controls) against players with an official defined rating;
  2. game count starts at the first game completed with at least 0,5 points (draw);
  3. forfeit games are not valild and do no update the game counter;
  4. when completed the 5 required games the value of evaluated rating is less than 1000 points, the player do not achieve the official rating and counters are reset.

The rules must be followed all official time controls: Bullet, Blitz and Rapid

Conditions of play

1. Only Arena full members can play rated games in Premium Chess Arena.

2. Arena Full members have the possibility to play unrated games and freely determine the time control.

3. Rated games use the following predetermined time controls:

a. For rapid chess: 15m, 25m, 45m, 10m + 10s, 15m + 10s, 25m + 10s, 45m + 10s
b. For blitz chess: 3m, 5m, 10m, 3m + 2s, 3m + 3s, 5m + 3s
c. For bullet chess: 1m, 2m, 1m + 1s, 1m + 2s

4. In case of disconnection during a game, the client application tries to reconnect automatically to the Premium Chess server. If this is not possible within 60 seconds, then the game is declared lost for the disconnected player.

Ratings formulae

1. Rating calculations use 2 digit decimal numbers for ratings and rating changes, but only the rounded integer part is displayed as rating.

2. A rating floor of 1000 points is used for ratings.

3. A member whose rating drops under the floor of 1000 points in a certain rating category, loses his/her rating for this time control category only. His first rating needs to be determined from the beginning for this time control category only following rules defined in item 5.

4. A new Arena member is considered to be unrated and a fixed training rating is assigned to him.

5. An unrated player can achieve his first rating in two stages:

a. The unrated player's first target is to achieve a draw or win an online game against a rated opponent.
b. The unrated player's second target is to complete 4 more games against rated opponents.

6. The first rating can be calculated based on these 5 results with the known formula:

a. Ra = the average rating of his opponents.
b. His first rating Rf is:

i. Rf = Ra if he scores 50% in his first 5 games.
ii. Rf = Ra + 20 for each half point scored over 50%
iii. Rf = Ra + dp where dp can be found in the table A

7. During the stages of first rating calculations, games between a rated player and an unrated player shall not affect the rating of the rated player.

8. The rating change after the completion of a single game between two rated players is calculated by the formula:

a. ΔR = score – PD

i. For each game the score is 1 or 0.5 or 0
ii. PD is taken from table B based on the rating difference D between the opponents.

b. The new rating after the completion of an online rated game is calculated by the formula: Rn = Ro+ (ΔR x K)

9. The K factors used are:

a. For rapid and blitz chess K = 20.
b. For bullet chess K = 10.
c. K = 40 for all players previously unrated in any of the three categories until they complete 30 rated games. This article applies only to the time control categories that the player was considered to be unrated.

10. Opponents' ratings are updated after the completion of their game.

11. Since 2 digit decimal numbers are used for Rn and ΔR, a member's rating is rounded to the nearest integer for display reasons only.

12. Fraction of 0.5 is rounded upwards. (Example: Rn = 2215.5 becomes Rn = 2216)

13. An example: It is possible that a player's rating does not change after a won game. A player with rating 1799.6 wins a game and gains 0.6 points. His new rating becomes 1800.2. Both ratings are shown as 1800.

Conversion tables

 Table A: conversion from fractional score, p, into rating differences, dp

p

dp

p

dp

p

dp

p

dp

p

dp

p

dp

1.0

800

.83

273

.66

117

.49

-7

.32

 -133

.15

-296

.99

677

.82

262

.65

110

.48

-14

.31

 -141

.14

-309

.98

589

.81

251

.64

102

.47

-21

.30

 -149

.13

-322

.97

538

.80

240

.63

95

.46

-29

.29

 -158

.12

-336

.96

501

.79

230

.62

87

.45

-36

.28

 -166

.11

-351

.95

470

.78

220

.61

80

.44

-43

.27

 -175

.10

-366

.94

444

.77

211

.60

72

.43

-50

.26

 -184

.09

-383

.93

422

.76

202

.59

65

.42

-57

.25

 -193

.08

-401

.92

401

.75

193

.58

57

.41

-65

.24

 -202

.07

-422

.91

383

.74

184

.57

50

.40

-72

.23

 -211

.06

-444

.90

366

.73

175

.56

43

.39

-80

.22

 -220

.05

-470

.89

351

.72

166

.55

36

.38

-87

.21

 -230

.04

-501

.88

336

.71

158

.54

29

.37

-95

.20

 -240

.03

-538

.87

322

.70

149

.53

21

.36

-102

.19

 -251

.02

-589

.86

309

.69

141

.52

14

.35

-110

.18

 -262

.01

-677

.85

296

.68

133

.51

7

.34

-117

.17

 -273

.00

-800

.84

284

.67

125

.50

0

.33

-125

.16

 -284

 

 

 

Table B: conversion of difference in rating, D, into scoring probability PD, for the higher, H, and the lower, L, rated player respectively.

D

PD

D

PD

 

 

Rtg Dif

H

L

Rtg Dif

H

L

0-3

.50

.50

 198-206

.76

.24

4-10

.51

.49

 207-215

.77

.23

11-17

.52

.48

 216-225

.78

.22

18-25

.53

.47

 226-235

.79

.21

26-32

.54

.46

 236-245

.80

.20

33-39

.55

.45

 246-256

.81

.19

40-46

.56

.44

 257-267

.82

.18

47-53

.57

.43

 268-278

.83

.17

54-61

.58

.42

 279-290

.84

.16

62-68

.59

.41

 291-302

.85

.15

69-76

.60

.40

 303-315

.86

.14

77-83

.61

.39

 316-328

.87

.13

84-91

.62

.38

 329-344

.88

.12

92-98

.63

.37

345-357

.89

.11

99-106

.64

.36

358-374

.90

.10

107-113

.65

.35

375-391

.91

.09

114-121

.66

.34

392-411

.92

.08

122-129

.67

.33

412-432

.93

.07

130-137

.68

.32

433-456

.94

.06

138-145

.69

.31

457-484

.95

.05

146-153

.70

.30

485-517

.96

.04

154-162

.71

.29

518-559

.97

.03

163-170

.72

.28

560-619

.98

.02

171-179

.73

.27

620-735

.99

.01

180-188

.74

.26

> 735

1.0

.00

189-197

.75

.25

 

 

 

 

 

 


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