Another 4C opening...

[Poky]

All vul.

 

4♣ pass ??

 

♠xx

♥KQJx

♦AKxx

♣Axx

 

4♣ shows ♣HHxxxxxx and nothing outside.

 

♠AK and ♥A are missing.

 

Let's say, it is good to raise 4♣ to 5♣ whenever opener has some of distributions:

0238

0328

1138

1318

1248

2038

3028.

(cannot have 4M)

 

Watching 2♠4♥4♦ what is the chance 5♣ will make (supposing partner has the ♣K)?

[whereagles]

just bid 5 and lean back :P

[paulg]

I generated 100 hands and 5♣ made (double dummy) on 61 deals and 6♣ made on 23.

 

Edit: this means bidding game is about a 61% proposition

Edited February 21, 2008 by cardsharp

[P_Marlowe]

Hi,

 

it is close, you have 3 1/2 tricks for

partner.

 

Most likely I bid 5C.

 

With kind regards

Marlowe

[655321]

Add me to the people who raise to 5♣ without worrying too much about it.

 

4m is a very effective preempt. I think you are wasting chances to use it by insisting a 4m opening follow your 'HHxxxxxx and nothing outside' rule.

[Poky]

4m is a very effective preempt. I think you are wasting chances to use it by insisting a 4m opening follow your 'HHxxxxxx and nothing outside' rule.

"Nothing outside" in terms of A, K or QQ - to be sure the risk of losing 3NT is minimal.

[Poky]

I generated 100 hands and 5♣ made (double dummy) on 61 deals and 6♣ made on 23.

What constraints you used?

 

Can you repeat, please, a simulation with these:

- fix: ♣KQJxxxxx;

- fix: 6-8 HCP (no big values outside, max Q or JJ);

- fix: no 4M, no 4♦.

 

TY.

 

P.S. What program do you use for these simulations?

[helene_t]

I generated 100 hands and 5♣ made (double dummy) on 61 deals and 6♣ made on 23.

 

Edit: this means bidding game is about a 61% proposition

Amazing. The a priori probability of having 2+ spades and 1+ hearts given an 8-card clubs must be close to 50%. (It is 2/3 with a 8221, 1/3 with a 8311, 1/3 with 8320 and 1/6 with 8410). Given our own shortness in spades and RHO failure to overcall the probability must be slightly larger. I would guess the chance of going down DD to be some 50%.

 

Single-dummy there is the added chance of a minor lead and p having a singleton ♦ and doubleton ♠. Or maybe he is allowed to have ♦Qx.

[paulg]

I generated 100 hands and 5♣ made (double dummy) on 61 deals and 6♣ made on 23.

What constraints you used?

 

Can you repeat, please, a simulation with these:

- fix: ♣KQJxxxxx;

- fix: 6-8 HCP (no big values outside, max Q or JJ);

- fix: no 4M, no 4♦.

 

TY.

 

P.S. What program do you use for these simulations?

This is a lot stricter than the parameters I used last time and it took significantly more time to generate the hands. Personally I think they are too strict; 4m do not happen that often and putting additional constraints on them mean that they'll be even rarer.

 

This was confirmed by the fact my database of hands only contained 30 that matched the criteria.

 

Of these, 11 (37%) made 11 tricks of which one (3%) made 12 tricks.

 

Of course these criteria greatly increase the chances of two spade losers together with the heart ace.

 

Paul

 

PS I use DealMaster Pro.

[the hog]

Don't strain the brain - 5C

[hrothgar]

Don't strain the brain - 5C

One of the rare occasions where I disagree with the Hog...

 

I suspect that we're going to lose three tricks before we cash 11 a large percentage of the time.

 

I lean towards passing

[paulg]

Don't strain the brain - 5C

My view too. Life's too short to worry about this type of problem.

 

The percentages are all well and good, but it's not a problem that comes up with sufficient frequency that they mean very much.

 

Paul

[helene_t]

Fair enough, but the probabilities are relatively easy to approximate with such a well-defined 4♣ opening. My estimate of 50% DD and somewhat more SD cannot be far off. Vuln at IMPs I don't think it's close.

[jdonn]

5♣ wtp?

[rbforster]

I think the earlier simulations were just small statistics and agree with later posts that game is relatively unlikely. Ignoring the off chance of a club loser (partner often has the K or it drops), the most likely shapes and their number of losers are given below:

 

Shape    Rel Prob    Non-Club Losers

2-2-1-8    16.3%    3

2-1-2-8    16.3%    3

1-2-2-8    13%    2

3-1-1-8    12.2%    3

1-3-1-8    7.6%    2

1-1-3-8    7.6%    2

3-0-2-8    5.4%    2

3-2-0-8    5.4%    3

2-0-3-8    4.2%    2.5

2-3-0-8    4.2%    3

0-2-3-8    2.8%    1

0-3-2-8    2.8%    1

1-0-4-8    1.3%    1.5

0-1-4-8    1%    1

 

The above probabilities are calculated just based on the known hand's suits, and assumes no useful honor cards except in clubs. In addition, the losers only count top tricks and assume we will take a ruffing finesse if necessary to dispose of diamond losers. It doesn't count the possibility of defensive ruffs, etc. The chances for a club loser are quite small - something like 8% of the time we'll lose a club (missing the K or it doesn't drop), given that all hands with 8 clubs and 2+ of KQJ are equally likely and conditioned on our club holding.

 

This leads to these outcomes (again ignoring the club suit):

 

Prob(4♣) 56.5%

Prob(5♣) 36.3%

Prob(6♣) 7.2%

 

I will add that if your partner makes undisciplined 4♣ preempts on 7♣(321) shape you are much worse off. Now you are very likely to have both 2 spades and a heart loser and the contract probabilities drop to:

 

Prob(4♣) 72.4%

Prob(5♣) 26.7%

Prob(6♣) 0.9%

 

Now game is quite poor.

[jdonn]

Don't forget all the times the opponents lead a diamond and you get to discard a loser. Not to mention some might underlead the ace of hearts from time to time on this auction...

[rbforster]

Let's say, it is good to raise 4♣ to 5♣ whenever opener has some distribution:

 

...

1248

...

Now that's some shape! Another 15 card hand! :)

[Apollo81]

Automatic 5♣

[Apollo81]

Not to mention some might underlead the ace of hearts from time to time on this auction...

...if they're on crack...

[TimG]

Of these, 11 (37%) made 11 tricks of which one (3%) made 12 tricks.

How often can the opponents make 4♠?

 

What are the passers going to do after 4♠ on their left, passed back to them?

[Apollo81]

Of these, 11 (37%) made 11 tricks of which one (3%) made 12 tricks.

How often can the opponents make 4♠?

 

What are the passers going to do after 4♠ on their left, passed back to them?

Double and lead the ♦A, and if I knew they were going to balance I'd definitely pass. The problem is that you could easily be cold for 5 (or even 6) clubs or the opps could give it to you on a minor suit lead even if it's not cold

[rbforster]

Don't forget all the times the opponents lead a diamond and you get to discard a loser. Not to mention some might underlead the ace of hearts from time to time on this auction...

I did some basic calculations for the opening lead, under standard leading (spade from AK or KQ but not Ax or AQ, no heart away from the A, otherwise all non-club suits equally likely). My estimates are:

 

P(♠ lead)=53%

P(♥ lead)=13%

P(♦ lead)=34%

 

The expected gain against the above shapes and relative probabilities was about 1/5 of a trick (0.19). This came from either pitching a quick major loser on a diamond lead opposite a singleton or void, or from guaranteeing the ruffing finesse in hearts when they lead into our void and set up fast pitches.

 

               Perfect   Real lead

Prob(4♣) 56.5% 41.1%

Prob(5♣) 36.3% 48.3%

Prob(6♣) 7.2% 10.6%

 

The first column is the "perfect lead" outcome, while the second reflects the realistic leads that may cost. Game becomes a reasonable proposition at both MPs and IMPs, even discounting advance sacrifices.

 

I will again caution against raising opposite 7♣(321) hands, where even with the lead the majority cannot make game.

 

               Perfect   Real lead

Prob(4♣) 72.4% 64.5%

Prob(5♣) 26.7% 34.1%

Prob(6♣) 0.9% 1.3%

 

I did not include the 0.08 or so of a club loser in any of these results (which reduces the total tricks slightly but not qualitatively).

[bid_em_up]

I think the earlier simulations were just small statistics and agree with later posts that game is relatively unlikely. Ignoring the off chance of a club loser (partner often has the K or it drops), the most likely shapes and their number of losers are given below:

 

Shape    Rel Prob    Non-Club Losers

2-2-1-8    16.3%    3

2-1-2-8    16.3%    3

1-2-2-8    13%    2

3-1-1-8    12.2%    3

1-3-1-8    7.6%    2

1-1-3-8    7.6%    2

3-0-2-8    5.4%    2

3-2-0-8    5.4%    3

2-0-3-8    4.2%    2.5

2-3-0-8    4.2%    3

0-2-3-8    2.8%    1

0-3-2-8    2.8%    1

1-0-4-8    1.3%    1.5

0-1-4-8    1%    1

 

The above probabilities are calculated just based on the known hand's suits, and assumes no useful honor cards except in clubs. In addition, the losers only count top tricks and assume we will take a ruffing finesse if necessary to dispose of diamond losers. It doesn't count the possibility of defensive ruffs, etc. The chances for a club loser are quite small - something like 8% of the time we'll lose a club (missing the K or it doesn't drop), given that all hands with 8 clubs and 2+ of KQJ are equally likely and conditioned on our club holding.

 

This leads to these outcomes (again ignoring the club suit):

 

Prob(4♣) 56.5%

Prob(5♣) 36.3%

Prob(6♣) 7.2%

 

I will add that if your partner makes undisciplined 4♣ preempts on 7♣(321) shape you are much worse off. Now you are very likely to have both 2 spades and a heart loser and the contract probabilities drop to:

 

Prob(4♣) 72.4%

Prob(5♣) 26.7%

Prob(6♣) 0.9%

 

Now game is quite poor.

Ok, what am I missing?

 

If I add the probabilities of all hands that have 2 or fewer non-club losers together, I infer than 5C makes 59.1% of tjme and that you have estimated losers of between 2.5/3 54.4% of the time.

 

Clearly this is not possible and even it it was, it appears to favor bidding 5C, not that game is unlikely.

[helene_t]

Don't forget all the times the opponents lead a diamond and you get to discard a loser. Not to mention some might underlead the ace of hearts from time to time on this auction...

Don't think many would underlead an ace after that auction (surely it could work if dummy has ♥KJx and declarer xx), but what could happen is the lead of heart and p is void.

[rbforster]

Ok, what am I missing?

 

If I add the probabilities of all hands that have 2 or fewer non-club losers together, I infer than 5C makes 59.1% of tjme and that you have estimated losers of between 2.5/3 54.4% of the time.

I think you might need to check your math.

 

Shape    Rel Prob    Non-Club Losers

2-2-1-8    16.3%    3

2-1-2-8    16.3%    3

3-1-1-8    12.2%    3

3-2-0-8    5.4%    3

2-3-0-8    4.2%    3

 

2-0-3-8    4.2%    2.5

For 3 loser hands, I see 16+16+12+5+4=53% without counting the 2.5's at half or something.