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13 pairs 2/1 ACBL

#1 User is online   dickiegera 

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Posted 2021-September-02, 15:58

Today at local club we had 13 prs and played a 7 table mitchel with E/W sitting out 4 BD's


Not nice if you are E/W.

Is there not a better movement.???
Director told me that with 15 prs we could have had a bump pair.

I thought There should be something better.



Thank you
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#2 User is offline   blackshoe 

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Posted 2021-September-02, 16:37

Lots of ways. Any way chosen, somebody will almost certainly complain about something.

Note: all the below are for 7 tables.

Some possibilities for 24 boards:

Reduced Howell in 12 rounds, with one of two stationary pairs absent. 2 boards per round.
Expanded Mitchell, 8 rounds, NS at tables 1-6 stationary, NS at table 7 missing (which means the sitout will move down the tables each round), 3 boards per round.

26 boards:

Straight Howell, 13 rounds, 2 boards per round, the stationary pair absent.

27 boards:

Reduced Howell in 9 rounds, 3 boards per round, one stationary pair absent.
Expanded Mitchell in 9 rounds, 3 boards per round.

28 boards:

Scrambled Mitchell, 4 boards per round, stationary pairs EW in rounds 6 and 7.

See Hallen, Hanner, Jannersten, Movements: A Fair Approach, 1994. There are other approaches, and some don't consider all of these "fair" (they object to the authors' approach to "fairness"). This was just the reference I had close to hand.

Note: a "straight" Howell has one stationary pair. A "reduced" Howell has more than one stationary pair and correspondingly fewer rounds. A Mitchell has as many stationary pairs as tables. An "expanded" Mitchell has (usually one) fewer stationary pairs and correspondingly more rounds. Generally, the number of rounds in a movement is equal to the number of moving pairs.

Google "duplicate bridge movements" and you'll get several good hits. I'd start with the wikipedia article.
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#3 User is offline   mycroft 

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Posted 2021-September-03, 17:41

I hate 4-board sitouts and 6.5 tables is awful.

As blackshoe says, it depends on how many boards you want to play.

There are downsides (some small, one big, one depends strongly on the makeup of the game) to any of the movements that give you more rounds than the Mitchell:
  • they're more complicated to set up and run (especially if you don't have a dealing machine. I remember many times shuffling the "other" 9-12 boards during the first round in my Howells - if you have a playing director, it's worse). But this is an education issue, mostly for the director, and it's pretty small.
  • they turn into one-winner games. Now, theoretically this is a good thing. But if your club "regularly" has a strong line (usually N-S) and a weak line, combining them into one likely makes more of the strong line players at the top of everything. There are a number of threads in these forums about how to "scramble" a Mitchell without provoking this, and the answer is "you can't. A fairer movement will have the better players winning more often. Try getting one of the stronger 'likes to be N-S' pairs to sit E-W for a month, and see what happens (but expect it to include '<pair> is just sitting E-W to fish masterpoints'."
  • It reduces (sometimes drastically) the number of stationary pairs available, and sometimes increases the non-bridge requirements for the ones that are left (have to turn the table for rounds 4,5, and 7, say). If you have a club where you *need* 6 stationaries, you don't really have many options.
  • More rounds are slower, especially if there's one slow pair, because they impact more tables more often. This can be huge.

For 13 pairs, if you're ACBL, there's also the external H7ROVER in ACBLSCOR, which bumps N-S for two boards and E-W for two boards. To be really fair, it should arrowswitch the last round, but it doesn't (I have a movement that does, but I think I built it myself). But it's a 24 board movement (all but one pair plays 22). And it's relay-byestand, so that's even more fun. And it's still one-winner. Ensure that your bumping pair is a) fast, and b) competent in understanding directions, and ensure that you've walked through the movement yourself before subjecting people to it.

I would always run the 13-round full Howell, provided we don't get into time trouble, and we have at most one "needs to be stationary" pair (actually, *I'd* do it even if I had two "needs to be stationary" pairs, provided we could make them meet the first or last round - almost everybody can move *once*. But that ups the "harder for the director" quotient *significantly*; I wouldn't ask "random club director" to do it.) All-play-all appeals to players, even those who would prefer to be in the "weak line" usually, and it's only a 2-board sitout. But expect it to take 10-15 minutes longer to play 13x2 than 7x4.

Also, small "trick", but whenever I have a sitout, unless it makes *my* life easier, it will be a N-S sitout. There are many people who just "prefer to sit", and that's their tradeoff. If I can set it up so that the "need to be stationary" pairs don't sit out, but the "lords of the table" do, I don't even have to worry about being unfair; when they complain, I can respond, "well, you can always go E-W next time".
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#4 User is offline   Vampyr 

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Posted 2021-September-04, 15:59

View Postmycroft, on 2021-September-03, 17:41, said:

For 13 pairs, if you're ACBL, there's also the external H7ROVER in ACBLSCOR, which bumps N-S for two boards and E-W for two boards. To be really fair, it should arrowswitch the last round, but it doesn't (I have a movement that does, but I think I built it myself). But it's a 24 board movement (all but one pair plays 22). And it's relay-byestand, so that's even more fun. And it's still one-winner. Ensure that your bumping pair is a) fast, and b) competent in understanding directions, and ensure that you've walked through the movement yourself before subjecting people to it.



How on earth do you produce a one-winner game with three separate lines and no arrow-switch?
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#5 User is offline   barmar 

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Posted 2021-September-07, 07:59

Many clubs have gotten rid of sitouts by using robots as fill-ins.

#6 User is offline   mycroft 

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Posted 2021-September-07, 10:13

You know the answer to that, Vampyr. Same way you can have an overall winner with two separate lines and no arrow-switch in a Mitchell. "Because we say so". Why do you think I created a personal one that *does* have the arrow-switch?
When I go to sea, don't fear for me, Fear For The Storm -- Birdie and the Swansong (tSCoSI)
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