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1m opening length probabilities

#1 User is offline   MickyB 

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Posted 2014-February-05, 18:50

Playing 15-17 NT, Better Minor, 1C on 3-3, 1D on 4-4:

What is the probability that partner has 3 cards/4 cards/5+ cards when he opens 1C? And likewise when he opens 1D?

Thanks.
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#2 User is offline   glen 

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Posted 2014-February-05, 19:11

 MickyB, on 2014-February-05, 18:50, said:

Playing 15-17 NT, Better Minor, 1C on 3-3, 1D on 4-4

Q. If you are playing 1C on 3-3, 1D on 4-4, can you still play better minor?
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#3 User is offline   PeterAlan 

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Posted 2014-February-05, 20:03

 MickyB, on 2014-February-05, 18:50, said:

Playing 15-17 NT, Better Minor, 1C on 3-3, 1D on 4-4:

What is the probability that partner has 3 cards/4 cards/5+ cards when he opens 1C? And likewise when he opens 1D?

Thanks.

Depends on what shape / HCP ranges 1m is opened. Or are you implicitly just considering balanced hands? Semi-balanced as well? Specify more fully, and I'll give you some numbers tomorrow.
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#4 User is offline   MickyB 

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Posted 2014-February-05, 23:09

 PeterAlan, on 2014-February-05, 20:03, said:

Depends on what shape / HCP ranges 1m is opened. Or are you implicitly just considering balanced hands? Semi-balanced as well? Specify more fully, and I'll give you some numbers tomorrow.


Ok let's say 11-21 unbal/12-14 bal/18-19 bal. Assume 5m422 in range opens 1NT. Thanks
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#5 User is offline   MickyB 

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Posted 2014-February-05, 23:13

 glen, on 2014-February-05, 19:11, said:

Q. If you are playing 1C on 3-3, 1D on 4-4, can you still play better minor?


It's a name for a method. It's what most people mean when they use the name. So, yes?

When I started playing duplicate, whenever we were asked if we played Better Minor, we would respond that we played Longer Minor. After the first dozen people all explained that that was what they had meant by "Better Minor", we gave in. Sometime afterwards I realised they had just been asking if we played 2+card club or 3+card minors.
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#6 User is offline   awm 

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Posted 2014-February-05, 23:45

 MickyB, on 2014-February-05, 23:13, said:

It's a name for a method. It's what most people mean when they use the name. So, yes?

When I started playing duplicate, whenever we were asked if we played Better Minor, we would respond that we played Longer Minor. After the first dozen people all explained that that was what they had meant by "Better Minor", we gave in. Sometime afterwards I realised they had just been asking if we played 2+card club or 3+card minors.


The way I've seen it used (and the way my partners and I use it), better minor means that with equal length we tend to open the stronger suit. For example:

KQxx Kxx AJx xxx would open 1, but KQxx Kxx xxx AJx would open 1

Kxx Ax AQxx xxxx would open 1, but Kxx Ax xxxx AQxx would open 1
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#7 User is offline   karlson 

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Posted 2014-February-06, 01:09

 awm, on 2014-February-05, 23:45, said:

The way I've seen it used (and the way my partners and I use it), better minor means that with equal length we tend to open the stronger suit. For example:

KQxx Kxx AJx xxx would open 1, but KQxx Kxx xxx AJx would open 1

Kxx Ax AQxx xxxx would open 1, but Kxx Ax xxxx AQxx would open 1


That seems to be the meaning in the US, but everywhere I've been in Europe, people use it to just mean "longer minor, 1c with 3-3, 1d with 4-4" as MickyB said. The alternatives being various forms of 2+ 1c or 1d.
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#8 User is offline   aguahombre 

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Posted 2014-February-06, 09:26

"Better minor" is another in the long line of terms we would not use to describe methods. I would have assumed if someone said better minor, AWM's interpretation was what they meant, but I shouldn't have to figure out what each region of the world calls things...especially when the words don't describe the agreements, as seemingly in this case in the EBU.

Balanced 3-3m or 4-4m open 1C in our style; balanced 4-4M open the only 3-card minor. Since that's what we do, that's what we say.
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#9 User is offline   Free 

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Posted 2014-February-06, 09:38

 karlson, on 2014-February-06, 01:09, said:

That seems to be the meaning in the US, but everywhere I've been in Europe, people use it to just mean "longer minor, 1c with 3-3, 1d with 4-4" as MickyB said. The alternatives being various forms of 2+ 1c or 1d.

You should visit Belgium. :)

With one partner I play 3 card minors where 1 could contain longer . When we explain sometimes we get the question "so you play longest minor?"... :rolleyes:
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#10 User is offline   PeterAlan 

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Posted 2014-February-06, 10:51

 MickyB, on 2014-February-05, 23:09, said:

Ok let's say 11-21 unbal/12-14 bal/18-19 bal. Assume 5m422 in range opens 1NT. Thanks

Basis:

  • Concerned only with 4-3-3-3 to 6-6-1-0 shapes; all 7+ suit hands excluded
  • Similarly all 22+ HCP hands, and 11 or 20/21 HCP balanced (4-3-3-3; 4-4-3-2; 5-3-3-2) hands, excluded (not opening 1x)
  • All 11-21 unbalanced opened (including 11 HCP 4-4-4-1)
  • 5-5 or 6-6 M-m open M; 6-5 m-M open m
  • 50% (ie 5m) of 15-17 HCP 5-4-2-2 open 1NT; no 6-3-2-2 do

If I've interpreted you correctly, of the hands with no 5+ card suit that are opening 1m:

  • 25% of 4-3-3-3 hands open 1 (4 card), 25% 1 (4 cards) and 50% 1 (3 cards)
  • 50% of 4-4-3-2 hands open 1 (4 card), 8.33% 1 (3 card), 33.33% 1 (4 card) and 8.33% 1 (3 card)
  • 75% of 4-4-4-1 hands open 1 (4 card) and 25% 1 (4 card)

(All 5+ card hands that open 1m have the same frequency of 1 and 1.)

Then (E&OE):

  • There are 234,166,911,312 1x opening hands in this sample space
  • 34,297,838,856 (14.65%) open 1NT and 77,785,551,954 (33.22%) 1M
  • 61,884,385,734 (26.43%) open 1, of which 2,637,795,564 (4.26%) are 3-card, 25,871,765,277 (41.81%) 4-card and 33,374,824,893 (53.93%) 5+ card suits
  • 60,199,134,768 (25.71%) open 1, of which 10,353,046,632 (17.20%) are 3-card, 16,471,263,243 (27.36%) 4-card and (again) 33,374,824,893 (55.44%) 5+ card suits

I can give you a fuller breakdown if needed: you should probably check what I've done, as I'm perfectly capable of slipping in a silly mistake!
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#11 User is offline   jogs 

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Posted 2014-February-06, 15:45

Who knows the relative probabilities? If pard opens 1 and RHO preempts 2 of a major, I just bid as if pard started with 5+ clubs.
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#12 User is offline   Zelandakh 

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Posted 2014-February-07, 07:12

 Free, on 2014-February-06, 09:38, said:

You should visit Belgium. :)

He should try Germany too. If a pair here describes their system as "Standard American" it means they open 1 with 4432 and a 1 opening promises 4.
(-: Zel :-)
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#13 User is offline   aguahombre 

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Posted 2014-February-07, 08:21

 jogs, on 2014-February-06, 15:45, said:

Who knows the relative probabilities? If pard opens 1 and RHO preempts 2 of a major, I just bid as if pard started with 5+ clubs.

Surely, you meant 3+, not 5+. Or do you have the pleasure of winning part-score battles in a 3-3 fit?
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#14 User is offline   helene_t 

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Posted 2014-February-07, 08:33

Here in Yorkshire, "SAYC" means Acol with strong NT and 5cM, 1=2+. But that is just as it is on BBO, I suppose.
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#15 User is offline   cherdano 

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Posted 2014-February-07, 08:33

 karlson, on 2014-February-06, 01:09, said:

That seems to be the meaning in the US, but everywhere I've been in Europe, people use it to just mean "longer minor, 1c with 3-3, 1d with 4-4" as MickyB said. The alternatives being various forms of 2+ 1c or 1d.

I thought it means "1C with 3=3, 1D with 3=2, no idea what partner does with 4=4".
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#16 User is offline   fromageGB 

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Posted 2014-February-18, 16:45

"Better minor" is one of those descriptions that should never be used, as a comparative ("better") depends solely on unspecified value judgements. Is AKQ better than 5432 ?
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#17 User is offline   Trinidad 

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Posted 2014-February-19, 07:10

A long time ago, I calculated these for our opening system, which is similar to yours. I now recalculated it for your structure.

I did the calculation as follows:
  • I assumed (which is not entirely true, but close enough for me) that he number of HCP in the hand and the shape are independent from each other.
  • I wrote out what distributions open 1/1
  • I looked up the probabilities for these distributions in the encyclopedia of bridge
  • I also looked up the probabilities for the number of HCP in a hand.
  • I added the probabilities for 11-20 HCPs (for unbalanced hands)
  • I added the probabilities for 11-14 and 18-19 HCPs (for balanced hands)
  • For each shape that would open 1/1, I calculated the probability that it would occur: P=P(shape)*P(in range), with P(in range) depending on whether this shape would open 1/2NT if in the 1/2NT range
  • In the end, I added the probabilities for the shapes with 3, 4, ..7 clubs/diamonds to get my histogram.
  • I did not calculate beyond 7 card suits: They are unlikely anyway and often will find another bid than 1m.


The result is the following table:

1
cards           probability (%)
3                         19.41
4                         29.72
5                         32.54
6                         15.08
7                         3.23

1
cards           probability (%)
3                         4.74
4                         43.26
5                         34.39
6                         14.52
7                         3.10

This calculation is pretty simple in a spreadsheet.

Rik
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#18 User is offline   Trinidad 

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Posted 2014-February-19, 07:23

 aguahombre, on 2014-February-07, 08:21, said:

Surely, you meant 3+, not 5+. Or do you have the pleasure of winning part-score battles in a 3-3 fit?

No, he meant 5+. The probability that partner has 3 clubs is significantly reduced by the fact that RHO has a six card major.

And competitive bidding is different from constructive bidding.
In constructive bidding, you should always bid based on what partner has promised (i.e. minimum length and strength).
In competitive bidding, you need to get your message across quickly, before LHO takes all your bidding space. This means that you need to base your bidding not on what partner promised (3 clubs), but on what he probably has (5 clubs in jogs view, 4,5 in mine).

Obviously, partner should realize that you have already bid based on what he is expected to have. He should not compete more with 4 clubs just because he has one more club than he promised. After all, he has 1 less club than he was expected to have.

Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
The most exciting phrase to hear in science, the one that heralds the new discoveries, is not “Eureka!” (I found it!), but “That’s funny…” – Isaac Asimov
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#19 User is offline   jogs 

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Posted 2014-February-19, 10:07

 aguahombre, on 2014-February-07, 08:21, said:

Surely, you meant 3+, not 5+. Or do you have the pleasure of winning part-score battles in a 3-3 fit?


Yes, I meant 5+. In vacuum 1 promises 3+. After opponents preempt conditions change. Granted opener may still have only 3, but it is extremely unlikely.
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#20 User is offline   aguahombre 

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Posted 2014-February-19, 12:27

 jogs, on 2014-February-19, 10:07, said:

Yes, I meant 5+. In vacuum 1 promises 3+. After opponents preempt conditions change. Granted opener may still have only 3, but it is extremely unlikely.

If that translates to bidding 3C after

1C (2S) ? with only three of them......wow.
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