The Rainbow Movement for Individual Duplicate Games

THE RAINBOW MOVEMENT for individual duplicate games bears a close resemblance to the Mitchell movement. In a Mitchell, there is on stationary group (the North-South pairs) and two moving units (the boards and the East-West pairs). In an individual game, however, there are five units which must be considered: boards, North players, South Players, West players and East players. One of the five can remain stationary, of course, but the other four must move, either in different directions or to different positions in the same direction.

This is how the Rainbow movement works. North players remain stationary. Boards move to the next lower table. South players move to the next higher table. East players skip one table higher. West players skip one table lower. Using table 3 as an example, the North player stays in his place, the boards move to table 2, South goes to table 4, East goes to table 5 and West goes to table 1.

Note: This movement works only with prime numbers of tables -- 5, 7, 11, 13, 17, 19, 23, for example. Since some of the players would meet the boards a second time at some point with other numbers of tables, these other numbers (6, 8, 12, 14, 15, etc.) require either the use of guide cards or to be divided into primes -- 12 tables can be divided into 5 and 7 table sections, for instance.

In the Rainbow movement, a player starting in one compass direction will never encounter another player who began in the same direction, either as a partner or as an opponent. No East player, for example, will ever be at the same table with another East player. But, as in the Mitchell movement, his scores will be compared with those of the other East players.

However, the players are not limited to a single partnership at each table. They normally play one board each with the other players at their table, if the movement calls for three-board rounds. This is done by having North remain stationary, while all the other players move in a clockwise direction around him as each board is played. If they are playing only two boards to a round, South and East can exchange seats after the first board is played. (But all players must be careful to take their original compass positions when they move to a new table, after a change is called.)

Player numbers: Numbers are assigned to each player in a Rainbow movement in the following manner: North takes the number of his table. West adds the total number of tables to the number of the table he is at. South adds twice the total number of tables to his table number. East adds three times the total to his table number. For instance, at table 3 of an 11-table game, North is 3, West is 14, South is 25 and East is 36.

--Extracted from Duplicate Bridge Direction by Alex Groner

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