Author: Christophe Theron
Date: 12:56:32 08/23/00
Go up one level in this thread
On August 23, 2000 at 15:31:14, Sylvain Renard wrote:
Given the blob I see below, are you surprised that the rules are not applied????
:) :) :)
Christophe
>For future computer chess arbiters :-)
>here are the complete rules of swiss system.
>You can see that there is a problem with round 6 and rule B3 :
>
>"
>The difference of the scores of two players paired against each other should be
>as small as possible and ideally zero.
>"
>
>Approved by the 1992 General Assembly.
>
>A. Introductory Remarks and Definitions
>
>A1. Rating
>It is advisable to check all ratings supplied by players. If no reliable rating
>is known for a player the arbiters should make an estimation of it as accurately
>as possible before the start of the tournament. (to convert German Ingo or
>British BCF use rating = 2840 -8 x INGO = 600 + 8 x BCF)
>
>A2. Order
>For pairing purposes only, the players are ranked in order of, respectively
>
>a) score
>b) rating
>c) FIDE-title (IGM-WGM-IM-WIM-FM-WFM-no title)
>d) alphabetically (unless it has been previously stated that this criterion has
>been replaced by another one)
>The order made before the first round (when all scores are obviously zero) is
>used to determine the pairing numbers: the highest one gets #1 etc.
>
>A3. Score brackets
>Players with equal scores constitute a homogeneous score bracket. Players who
>remain unpaired after the pairing of a score bracket will be moved down to the
>next score bracket, which will therefore be heterogeneous. When pairing a
>heterogeneous score bracket these players moved down are always paired first
>whenever possible, giving rise to a remainder score bracket which is always
>treated as a homogeneous one.
>
>A heterogeneous score bracket of which at least half of the players have come
>from a higher score bracket is also treated as though it was homogeneous.
>
>
>A4. Floats
>By pairing a heterogeneous score bracket, players with unequal scores will be
>paired. To ensure that this will not happen to the same players again in the
>next round this is written down on the pairing card. The higher ranked player
>receives a downfloat ( ), the lower one an upfloat ( ).
>
>A5. Byes
>
>Should the total number of players be (or become) odd, one player ends up
>unpaired. This player receives a bye: no opponent, no color, 1 point. A bye is
>considered to be a downfloat.
>
>A6. Subgroups
>To make the pairing, each score bracket will be divided into two subgroups, to
>be called S1 and S2. In a heterogeneous score bracket S1 contains all players
>moved down from a higher score bracket. In a homogeneous score bracket S1
>contains the higher half (rounding downwards) of the number of players in the
>score bracket.
>
>The number of players in S1 will be indicated by "p", indicating the number of
>pairings to be made. In both cases S2 contains all other players of the score
>bracket. In both S1 and S2 players are ordered according to A2.
>
>A7. Color differences and color preferences
>The color difference of a player is the number of games played with white minus
>the number of games played with black by this player. After a round the color
>preference can be determined for every player.
>
>
>a) An absolute color preference occurs when a player's color difference is
>greater that 1 or less than -1, or when a player played with the same color in
>the two latest rounds. The preference is white when the color difference is << 0
>or when the last two games were played with black, otherwise black. In this case
>the (obligatory) color is already written down on the score card. (This rule is
>not in effect when pairing players with a score of over 50% in the last round).
>
>b) A strong color preference occurs when a player's color difference is unequal
>to zero. The preference is white when the color difference is << 0, black
>otherwise.
>c) A mild color preference occurs when a player's color difference is zero, the
>preference being to alternate the color with respect to the previous game. In
>this case the color difference is written down as +0 or -0 depending on the
>color of the previous game (white or black respectively). Before the first
>round the color preference of one player (often the highest one) is determined
>by lot.
>
>
>A8. Definition of "x"
>The number of pairings which can be made in a score bracket, either homogeneous
>or heterogeneous, not fulfilling all color preferences, is represented by the
>symbol x.
>
>x can be calculated as follows:
>w=number of players having a color preference white.
>b=number of players having a color preference black.
>q=number of players in the score bracket divided by 2, rounded upwards.
>If b >> w then x = b-q, else x = w-q.
>
>A9. Transpositions and exchanges
>
>a. In order to make a sound pairing it is often necessary to change the order in
>S2. The Rules to make such a change, called a transposition, are in D1.
>
>b. In a homogeneous score bracket it may be necessary to exchange players from
>S1 and S2. rules for exchanges are found under D2. After each exchange both S1
>and S2 are to be ordered according to A2.
>
>B. Pairing Criteria
>
>Absolute Criteria
>(These may not be violated. If necessary players will be moved down to a lower
>score bracket.)
>
>
>B1.
>a. Two players shall not meet more than once.
>b. A player who has received a point without playing, either through a bye or
>due to an opponent not appearing in time, shall not receive a bye.
>
>B2.
>a. No player's color difference will become >>+2 or <<-2.
>b. No player will receive the same color three times in row.
>
>
>Relative Criteria
>(These are in descending priority. They should be fulfilled as much as possible.
>To comply with these criteria, transpositions or even exchanges may be applied,
>but no player should be moved down to a lower score bracket).
>
>
>B3.
>The difference of the scores of two players paired against each other should be
>as small as possible and ideally zero.
>
>B4.
>As many players as possible receive their color preference. (Whenever x of a
>score bracket is unequal to zero this rule will have to be ignored. x is
>deducted by one each time a color preference cannot be granted.)
>
>B5.
>No player shall receive an identical float in two consecutive rounds.
>
>B6.
>No player shall have an identical float as two rounds before.
>
>
>Note: B2, B5 and B6 do not apply when pairing players with a score of over 50%
>in the last round.
>
>C. Pairing Procedures
>
>Starting with the highest score bracket apply the following procedures to all
>score brackets until an acceptable pairing is obtained. Afterwards the color
>allocation rules (E) are used to determine which players will play with white.
>
>C1.
>- If the score bracket contains a player for whom no opponent can be
>found within this score bracket without violating B1 or B2 then:
>
>- if this player was moved down from a higher score bracket apply C12.
>- if this score bracket is the lowest one apply C13. in all other cases:
>move this player down to the next score bracket.
>
>C2.
>Determine x according to A8.
>
>C3.
>Determine p according to A6.
>
>C4.
>Put the highest players in S1, all other players in S2.
>
>C5.
>Order the players in S1 and S2 according to A2.
>
>C6.
>Pair the highest player of S1 against the highest one of S2, the second highest
>one of S1 against the second highest one of S2, etc. If now p pairings are
>obtained in compliance with B1 and B2 the pairing of this score bracket is
>considered complete.
>
>
>- In case of a homogeneous score bracket: remaining players are moved
>down to the next score bracket. With this
>score bracket restart at C1.
>- In case of a heterogeneous score bracket: only players moved down were
>paired so far. Start at C2 with the homogeneous remainder group.
>
>C7.
>Apply a new transposition of S2 according to D1 and restart at C6.
>
>C8.
>In case of a homogeneous (remainder) group: apply a new exchange between S1 and
>S2 according to D2. Restart at C5.
>
>C9.
>Drop criterion B6 and B5 (in this order) for downfloats and restart at C4.
>
>C10.
>In case of a homogeneous remainder group: undo the pairing of the lowest moved
>down player paired and try to find a different opponent for this player by
>restarting at C7.
>
>If no alternative pairing for this player exists then drop criterion B6 first
>and then B5 for upfloats and restart at
>C2.
>
>C11.
>As long as x is less than p: increase x by 1. When pairing a remainder group
>undo all pairings of players moved down also. Restart at C3.
>
>C12.
>In case of a heterogeneous group: undo the pairing of the previous score
>bracket. If in this previous score bracket a pairing can be made whereby another
>player will be moved down to the current one, and this now allows p pairing to
>be made then this pairing in the previous score bracket will be accepted.
>
>C13.
>In case of the lowest score bracket: the pairing of the penultimate score
>bracket is undone. Try to find another pairing in the penultimate score bracket
>which will allow a pairing in the lowest score bracket. If in the penultimate
>score bracket p becomes zero (i.e. no pairing can be found which will allow a
>correct pairing for the lowest score bracket) then the two lowest score brackets
>are joined into a new lowest score bracket. Because now another score bracket is
>the penultimate one C13 can be repeated until an acceptable pairing is obtained.
>
>C14.
>Decrease p by 1 (and if the original value of x was greater than zero decrease x
>by 1 as well). As long as p is unequal to zero restart at C4. If p equals zero
>the entire score bracket is moved down to the next one. Restart with this score
>bracket at C1.
>
>
>D. Transposition and Exchange Procedures
>
>Example: S1 contains players 1, 2, 3 and 4 (in this sequence); S2 contains
>players 5, 6, 7 and 8 (in this sequence).
>
>D1.
>Transpositions within S2 should start with the lowest players, with descending
>priority:
>
>a) 5-6-8-7;
>b) 5-7-6-8
>c) 5-7-8-6
>d) 5-8-6-7
>e) 5-8-7-6
>f) 6-5-7-8
>g) 6-5-8-7, etc.
>
>Hint: put all numbers constructable with the digits 5, 6, 7 and 8 in ascending
>order.
>
>D2.
>When applying an exchange between S1 and S2 the difference between the numbers
>exchanged should be as small as possible. When differences of various options
>are equal take the one concerning the lowest player of S1.
>
> Exchange one player Exchange two players
>
>
> S1 S1
> 4 3 2 3+4 2+4 2+3
> 5 a c f 5+6 j l o
> 6 b e h 5+7 k n q
> 7 d g i 6+7 m p r
>
>
>The above matrices contain the sequence in which exchanges should be applied.
>
>Exchanging one player: a) 4 and 5; b) 4 and 6; c) 3 and 5; etc. until i) 2 and
>7.
>
>Exchanging two players: j) 3+4 with 5+6; k) 3+4 with 5+7; l) 2+4 with 5+6 etc.
>After each exchange both S1 and S2 should be ordered according to A2.
>
>Remark: if the number of players in a score bracket is odd, S1 contains one
>player less than S2. So with 7 players S1 contains players 1, 2 and 3, S2 4, 5,
>6 and 7. The exchanges needed in that case can be found from the above ones
>bydeducting all numbers in S1 and S2 by 1. The last column of the second matrix
>has then become obsolete.
>
>
>E. Color Allocation Rules
>For each pairing apply (with descending priority):
>
>E1.
>Grant both color preferences.
>
>E2.
>Grant the stronger color preference.
>
>E3.
>Alternate the colors to the most recent round in which they played with
>different colors.
>
>E4.
>Grant the color preference of the higher ranked player. In the first round all
>even numbered players in S1 will receive a color different from all odd numbered
>players in S1.
>
>F. Final Remarks
>
>F1.
>After a pairing is complete sort the pairing before making them public. The
>sorting criteria are (with descending priority)
>
>- the score of the higher player of the pairing involved;
>- the sum of the scores of both players of the pairing involved;
>- the rank according to A2 of the higher player of the pairing involved.
>
>F2.
>Byes, and pairing not actually played, or lost by one of the players due to
>arriving late or not at all, will not be taken into account with respect to
>color, Such a pairing is not considered to be illegal in future rounds.
>
>F3.
>A player who after five round has a color history of BWW-B (i.e. no valid game
>in round 4) will be treated as -BWWB with respect to E3. So WB-WB will count as
>-WBWB and BWW-B-W as --BWWBW.
>
>F4.
>Because all players are in one homogeneous score bracket before the start of
>round one and are ordered according to A2 the highest player of S1 will play
>against the highest player of S2 and if the number of players is odd the lowest
>ranked player will receive a bye.
>
>
>F5.
>Players who withdraw from the tournament will no longer be paired. Players known
>in advance not to play in a particular round are not paired in that round and
>score 0.
>
>F6.
>A pairing officially made public shall not be changed unless it violates the
>absolute pairing criteria (B1 and B2).
>
>F7.
>If either result was written down incorrectly, or a game was played with the
>wrong colors, or a player's rating has to be corrected, then this will only
>affect pairing yet to be made.
>
>Whether it will affect a pairing already made public but not yet played should
>be decided by the arbiter.
>
>Unless the rules of the tournament state otherwise:
>
>F8.
>Players who are absent during a round without notification to the arbiter will
>be considered to have withdrawn themselves.
>
>F9.
>Adjourned games are considered draws for pairing purposes only.
>
>F10.
>In order to make the final standings the following criteria apply (in descending
>priority):
>
>
>- the highest number of points scored; should this be equal for several
>participants prize money should be shared;
>- where it concerns the first place: the best result in games played
>against each other;
>- the highest average rating of the opponents;
>- the drawing of lots.
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