BCF Swiss Pairing Rules

These are the BCF Swiss Pairing Rules as I understand them. I can not remember where I got this list from, but if some one can confirm or correct these rules it would be greatly appreciated.

1.              No player may play the same opponent twice.

2.              When making pairings the priorities are:
  a) score
  b) colour
    i) equalisation
    ii) alternation
    iii) balance over recent rounds
  c) grading
  d) float history
Where alterations from the perfect application of these rules must be made, the principle of minimum disturbance is applied.

3.              Ungraded players are allocated an estimated grade using the best information available. This can be amended for particular players in the light of experience during the tournament.

4.              Pairing cards are arranged in descending order of grade. Players with the same grade are placed in order of FIDE title status (GM, WGM, IM, WIM, FM, WFM, no title), and then alphabetically. Pairings for a particular round can sometimes be improved by changing the order of players having the same grade.

5.              If a bye is required in round 1, it is given to a player at or just below the median.

6.              For subsequent rounds the bye is chosen, if possible, from the lowest score group, looking first at the larger colour group working from the median downwards, seeking a players who has not yet had a bye and who is not due to receive a pre-arranged bye. If this fails, the bye is chosen using the same criteria but working upwards from the median.

7.              The chosen player receives a full point, without colour.

8.              Players are paired top half v bottom half in descending grading order with the colour on board one being decided by lot, e.g. with 64 players:- 1 v 33, 34 v 2, 3 v 35 or 33 v 1, 2 v 34, 35 v 3.

9.              As far as possible, players are paired within their own score group.

10.          Where this is not possible, the minimum number of players are floated by the minimum score differences (see rules 19-24).

11.          The highest score level is considered first, then the next and so on.

12.          On each score level the top half is paired against the bottom half, keeping as close as possible to grading order. When this is not possible, the players on the border of the top and bottom halves are exchanged by the minimum extent necessary.

13.          This policy is only broken to avoid blockage of the pairings, when the minimum number of score levels , working upwards, are disturbed.

14.          Within each score group, pairing cards are sorted into white seekers and black seekers, each group being arranged into descending order (see rule 4)

15.          As far as possible, white seekers play black seekers.

16.          Where there is an excess of one colour group, transfers are made which involve those players with the weakest claim for the original colour, e.g. in the following example after four round, sequence 1 has the strongest claim to white; sequence 12 has the strongest claim to black.

Strong W Seekers               Weaker W Seekers
1 BWBB,  2 BBWB,  3BBBW              4 WWBB,  5 WBWB,  6 BWWB

Weaker B Seekers              Strong B Seekers
7 WBBW,  8 BWBW,  9 BBWW              10 WWWB,  11 WWBW,  12 WBWW

17.          If the score level requires a float (or floats) and has an excess of one colour and the linked score level(s) below has (have) as excess of the same colour, they are treated as one score level for the purpose of colour transfers, care being taken not to infringe rule 10.

18.          Where colour transfers can be made which involve players having identical colour sequences, a transfer is not made which will cause that player to be floated unless such a move is required to produce a top half upfloat or to reduce the number of further floaters or colour transfers.

19.          Where there is an odd number of players on a score level, a players must be floated down to the next score level.

20.          The downfloat is chosen from the larger colour group. Work from the median of the score level downwards to the bottom, seeking a player who:
    a) did not downfloat in either of the previous two rounds
    b) did not downfloat in the previous round
    c) has no worse a downfloat history than any other player in the complete colour group of the score
                  level being considered.
If this fails to produce the downfloater, work from the median up to the top, using criteria b) and c).

21.          The opponent for the upfloater is chosen from the opposite colour group. Work from the median upwards, seeking a player who:
    a) did not upfloat in either of the previous two rounds
    b) did not upfloat in the previous round
    c) has no worse an upfloat history than any other player in the complete colour group of the score
                  level being considered.
If this fails to produce the upfloater, work from the median down to the bottom, using criteria b) and c).

22.          If the chosen upfloater has already played the chosen downfloater, the alternative pairing which best satisfies both rule 20 and 21 is chosen.

23.          When the floaters have been selected the players on each score level are paired according to rule 12.

24.          Selected floaters are not altered unless change reduces the number of a) further floaters, b) colour transfers, or c) exchanges of players on the border of the top and bottom halves of the score level being considered.

25.          When two players with identical colour sequences are paired together, the correct colour is given to the higher-ranking player. Where two players have the same score, this is the higher-graded player. Where two players have different scores it is the player with the higher score.

26.          In a long tournament, care must be taken that the priorities are not violated for players on the lowest score group.

27.          Once a draw has been published, if adjustments or alterations are necessary, they are made so as to produce the least disturbance to the draw.

28.          The British Championship will not normally start with a bye.

29.          In the British Championship the highest-graded player takes white in odd-number years.

30.          In FIDE rated tournaments, the BCF grades of non FIDE rated players are converted to their FIDE equivalent but clearly shown as such on cards and charts.

31.          In FIDE rated tournaments, the word ‘rating’ is used instead of ‘grade’ and ‘grading’ in rules 1-29.
 

Notes

[1]   In round 1, pairings between relatives, players from the same club, distant local area, or foreign country are best avoided. The extent to which such pairings are avoided in later rounds is at the discretion of the arbiter.

[2]   Full point byes can sometimes be avoided by the use of fillers or cross-pairings between sections. These options may not be appropriate for championship events.

[3]   In round 2, pairings between players who received half point byes in round 1 should be avoided.

[4]   In rule 25, where the two players have less than 50%, the correct colour may be given to the lower ranking player.

[5]   If two players are paired together, but one or both defaults, although they are still eligible to be paired together subsequently, this should be avoided, provided priorities a) score and b) colour balance are not violated.

[6]   In the last round only, colour alternation rules may be less important than some other priorities.

[7]     In the last round only, for players not in contention for a prize, rule 9 may be relaxed to avoid a colour difference of 3 (e.g. 4 whites and 7 blacks).