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Raising 1C with 4 trumps


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Playing Standard, 15-17 NT & better minor,

I believe the chance of a 1 opener having 4+ clubs is about 85%. Right?

 

What is the figure when responder has four clubs?

So the auction goes:

1 - (pass or bid) - ?

 

Responder has four trumps, no major to show and is thinking of raising to 2 or 3.

What is the chance of an 8+ card fit?

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Obviously the fact that we have 4 clubs increases the chance that partner dos not hold length, but there is another huge factor at work - RHO's pass over 1.

 

Particularly if we are very weak, then RHO's pass over 1 becomes the equivalent of the dog that didn't bark. If partner had long clubs, the chances of RHO not being able to overcall are pretty small, so the profile of hands becomes skewed towards partner holding a balanced hand with relatively short clubs.

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Not to be dismissed also is the possibility of agreeing that a 1N response shows 4 card Club support. That consults opener on whether or not to retreat, and removes broadly the same amount of bidding space.

This is, of course, a very common old-fashioned understanding. If responder shows four of any of , then responding NT must be showing four . If it is your plan to raise with only four of them, then it should be your partnership understanding that responding NT shows four ; otherwise, you'd never bid NT over a 1 opening.

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About 71% for 8+ cards fit in clubs.

 

But I would only raise with 4 card support after overcall or t/o double. But the raise with 4 feels a routine action in a competitive auction.

 

 

northbal = shape(north, any 4432 + any 4333 + any 5332 - 5xxx - x5xx)

c1_unbal = hcp(north) > 10 && hcp(north) < 22 &&
               !northbal &&
               ((clubs(north) > diamonds(north) &&
               clubs(north) > hearts(north) &&
               clubs(north) > spades(north)) || shape(north, 4414))

c1_bal = ((hcp(north) > 11 && hcp(north) < 15) ||
               (hcp(north) > 17 && hcp(north) < 20)) &&
               northbal && diamonds(north) < 4

c1 = c1_unbal || c1_bal

condition c1 && hcp(south) >= 5 &&
       shape(south, 2344 + 3244 + 3334)

action
       average "8+ club fit" clubs(north) >= 4,


8+ club fit: 0.708293
Generated 10000000 hands
Produced 47870 hands
Initial random seed 1424543431
Time needed    5.484 sec

 

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About 71% for 8+ cards fit in clubs.

 

But I would only raise with 4 card support after overcall or t/o double. But the raise with 4 feels a routine action in a competitive auction.

 

 

northbal = shape(north, any 4432 + any 4333 + any 5332 - 5xxx - x5xx)

c1_unbal = hcp(north) > 10 && hcp(north) < 22 &&
               !northbal &&
               ((clubs(north) > diamonds(north) &&
               clubs(north) > hearts(north) &&
               clubs(north) > spades(north)) || shape(north, 4414))

c1_bal = ((hcp(north) > 11 && hcp(north) < 15) ||
               (hcp(north) > 17 && hcp(north) < 20)) &&
               northbal && diamonds(north) < 4

c1 = c1_unbal || c1_bal

condition c1 && hcp(south) >= 5 &&
       shape(south, 2344 + 3244 + 3334)

action
       average "8+ club fit" clubs(north) >= 4,


8+ club fit: 0.708293
Generated 10000000 hands
Produced 47870 hands
Initial random seed 1424543431
Time needed    5.484 sec

I'm not really sure how to read the code, but are you stipulating that Opener would open 1 with (32)44 shape (with appropriate HCP)?

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