varma

Documentation

Overview

Package varma implements the Varma Tables pre-processing number assignment scheme for round-robin chess tournaments (FIDE C.05 Annex 2).

Varma Tables assign pairing numbers to players so that players from the same federation (country) are spread across the tournament schedule, avoiding same-federation clashes in early rounds.

The scheme covers tournaments of 2-24 players. For 2-8 players the tables are trivial (sequential assignment). For 9-24 players, FIDE provides specific group assignments (A, B, C, D) that achieve optimal federation separation in the Berger table rotation.

Usage: call Groups(n) to get the 4 group assignments for n players, then call Assign(players) to assign pairing numbers based on federation.

Index

• func Assign(players []chesspairing.PlayerEntry) ([]chesspairing.PlayerEntry, error)
• type Group
  • func Groups(n int) ([4]Group, error)

Functions

func Assign

func Assign(players []chesspairing.PlayerEntry) ([]chesspairing.PlayerEntry, error)

Assign assigns pairing numbers to players using the Varma Tables scheme (FIDE C.05 Annex 2). Players from the same federation are spread across the 4 Varma groups to avoid same-federation clashes in early rounds.

The returned slice is ordered by pairing number (index 0 = pairing number 1). Only active players are included. Inactive players are excluded from the result.

Algorithm:

1. Filter to active players only.
2. Get the Varma group table for the active player count.
3. Group players by federation, sorted by federation size descending, then alphabetically by federation code.
4. For each federation (largest first), pick the first Varma group (A→D) with enough available slots. If no single group has enough, spill across groups (largest-available first).
5. Within each federation, assign players to slots in alphabetical order by DisplayName.

Returns an error if the active player count is < 2 or > 24.

Types

type Group

type Group struct {
	Label   byte  // 'A', 'B', 'C', or 'D'
	Numbers []int // pairing number slots, 1-based, sorted ascending
}

Group represents one of the four Varma groups (A, B, C, D). Numbers are the pairing number slots available in this group, sorted in ascending order.

func Groups

func Groups(n int) ([4]Group, error)

Groups returns the four Varma group assignments for n players.

For 2-8 players, all numbers are placed in group A (trivial — no federation separation benefit with fewer than 9 players).

For 9-24 players, the FIDE C.05 Annex 2 lookup tables are used. Odd counts use the next-even table with the highest number removed (that number would be the bye dummy in round-robin).

Returns an error for n < 2 or n > 24.