Pairings

Rules for Swiss Systems

• Number of rounds should be declared beforehand
• Two players cannot play each other more than once
• If there is an odd number of players, one player is unpaired who gets a bye (Whether they get a point or not is up to the tournament).
• A player who received points without playing cannot get a bye
• Players are generally paired to others with the same score

Other rules:

• If you have a defaulted game (where one player doesn't appear), they can be paired together in a later round
• Byes have no colour. They are neither white or black.
• The number of whites and blacks that a player gets to play as should not be greater than 2 (i.e. you can't have 2 whites more than black or two blacks more than white) unless it is the last round.
• Colors should try to be balanced and have alternating colors

How to do pairings

Notes from the course

• Order members by rating (1 is highest rating)
  • For unrated players you can use a national rating (converted) and it should be shown (for example, with an asterisk). This is so we don't take these into account for calculating ratings.
  • For unrated players with no other ratings, normally you'd put them at the bottom in alphabetical order
• Figure out what the top seed is - this is either white or black (top seed as white means player 1 plays white). This is generally random

CB represents color balance - positive is white and negative is black.

• We want to get rid of the lowest player from the larger colour group. We only down float from the larger color group
• The colour columns on the pairing table represents the colour they are due to play.
• The higher ranked player keeps their colour sequence if there is a player that has to change colour

When we're doing "top half vs bottom half", we ignore floats

Basically the order of stuff we do is:

• Make sure players aren't playing the same players they've played
• Try to pair people with the same score
• Float
• We want a player to play the highest rated player
• We don't do double float unless there is no other choice
• Everything else
• Colour change (we want to avoid this wherever possible)

When you're doing pairings, you need to think: What is the optimal pairing? (as in, can we pair top and top) Can we do this? If so, do so. We can relax the rule of "top player should play the colour they want" in the case of say, the opponent has two consecutive white games.

So remember: What is the optimal pairing

Try to get the ideal pairing whenever possible

We can also consider doing a "median split" - changing what the top and bottom half are.

You publish the pairings and then find some byes. In this case, you pair the players with no opponents (if the players agree, otherwise if they ask for the point you give them the point).

How to do pairings (My notes from practising)

1. Construct the table of points and the colours that players are due, ordered by player number when in the same points group

2. If we have too many people (odd number) in the current (highest) points group, float one down and ignore them:

   1. When selecting a player to float down, choose the lowest pin from the biggest color group. If you have 3 white and 2 black, float down the white.

3. Now pair top half vs bottom half. Make sure we're not pairing people who have played against each other before. When doing top half vs bottom half, this is where you're allowed to change color.

4. When it comes to floats (pairing a float down with an opponent - i.e. choosing someone to float up):

   1. If the opponent has floated up before, reject.
   2. If the opponent has played before, reject.
   3. Select a player with the highest pin and right color. If we already know we're going to do a color swap, then we prioritize the highest pin which hasn't already upfloated.

5. Do a color switch (lowest possible priority - you basically never ever want to do this UNLESS you have to)