[mikeh]

hrothgar, on 2011-July-26, 12:26, said:

FWIW, I threw together a simple MATLAB script to check on the expected number of Diamonds in partner's hand.
This script assumes that the Spade length in partner's hand is <= 3 (which obviously ignores suit quality)


Estimated Diamond length
Four = 0.5792
Five = 0.3349
Six = 0.0794
Seven = 0.0065

MATLAB Code

%% Shape

Shape(1:12,1) = 'C';
Shape(13:19) = 'D';
Shape(20:29) = 'H';
Shape(30:39) = 'S';


%% shuffle

simlength = 10000000

MC_Result = zeros(simlength, 4);

for i = 1:simlength
    
    index = randperm(39);
    Shape = Shape(index);    
    foo = Shape(1:13,1);
    
    MC_Result(i, 1) = length(foo(foo == 'C'));
    MC_Result(i, 2) = length(foo(foo == 'D'));
    MC_Result(i, 3) = length(foo(foo == 'H'));
    MC_Result(i, 4) = length(foo(foo == 'S'));
    
end

Voids = MC_Result(:,3) == 0;
MC_Result2 = MC_Result(Voids,:);

Spades = MC_Result2(:,4) <= 4;
MC_Result3 = MC_Result2(Spades, :);

index = MC_Result3(:,2) >=4;
Raises = MC_Result3(index,:);

Four = length(Raises(Raises(:,2) == 4))/length(Raises)
Five = length(Raises(Raises(:,2) == 5))/length(Raises)
Six = length(Raises(Raises(:,2) == 6))/length(Raises)
Seven = length(Raises(Raises(:,2) == 7))/length(Raises)

Thanks for the effort, but don't we, a posteriori, have to filter these results for the hands on which partner, holding 4=6 (or wilder) in the minors would have bid clubs? For example, with say Axx void xxxx AKQxxx, I suspect that many players would have chosen a call other than 4♥. My view is that it is not possible to filter these results objectively in that two players, even of equal skill, would not agree on exactly where the 'raise diamonds/bid clubs' divide should be made.

In terms of the usage of a priori and a posteriori, it seems to me that your analysis aims more at a posteriori, but without the benefit of the filter I suggest. But I found it interesting and I thank you.

[hrothgar]

mikeh, on 2011-July-26, 13:11, said:

Thanks for the effort, but don't we, a posteriori, have to filter these results for the hands on which partner, holding 4=6 (or wilder) in the minors would have bid clubs? For example, with say Axx void xxxx AKQxxx, I suspect that many players would have chosen a call other than 4♥. My view is that it is not possible to filter these results objectively in that two players, even of equal skill, would not agree on exactly where the 'raise diamonds/bid clubs' divide should be made.

I readily admit that this sim doesn't factor in the failure to make a variety of other bids (fit jumps and the like)
(Honesty, the main reason that I threw this together was that I wanted to tweak the MATLAB hand generator to look at shape rather than just strength)

Even so, given the vast dispariety between hand with 4 diamonds and hands with 5+ diamonds, I'd be surprised if 5+ ever came to dominate.

As for the whole a priori issue...

To me, this only really gets interesting if you have a multi stage auction

For example, suppose that the auction started

1D - (1H) - 2C - (P)
2D - (P) - 3D

Here partner originally bid clubs and then later bid diamonds causing one to update the priors

[y66]

Bidding 5C after valuing AKx of hearts opposite a void as "not wasted" when partner has Axx or Axxx of spades is not the same thing as placing partner with those cards. It places him with the sense to sign off in 5D if he has Kxx(x) of spades underneath the likely holder of the SA. Of course, if he signs off and they lead spades, which I suppose they will, I may regret my 5C bid. But I will regret bidding 5D more if we play there when 6D is making.

[FrancesHinden]

nige1, on 2011-July-25, 13:40, said:

BTW, gnasher, for the last quiz you gave us, you did not reveal partner's hand or what would have worked, in practice.
Philosophers like matmat may argue that when assessing the quality of a bid, what works is not necessarily correct (and vice versa) but we result-merchants still relish our pound of flesh.[/hv]

This is a bit of a purist's thread, I'm afraid. As long as you don't pass 4H or take a complete flyer later in the auction, you'll end up in the same contract whatever you do now.
On this particular hand I agree with gnasher that the interest is in what the best call is on opener's hand, not what the result is.

[Mbodell]

OleBerg, on 2011-July-26, 12:16, said:

At the table nothing but 5♦ would enter my mind.

Having followed this thread got me to think a little, but not enough to change my mind.

I agree with this, although I'm much less confident of 5♦ now.

[cherdano]

When I read a post by Mikeh on legal matters, I start with the assumption that he knows what he is talking about, even if he makes claims that I find extremely surprising.

Anyway, by "a priori" probabilities I meant the probabilities a priori to partner's 4♥ bid - i.e. given our hand and LHO's 2♥ overcall, there are the probabilities a and b that partner is 0=4 or 0=5 in the red suits. The relative probabilities that matter can be computed by comparing a * p(a|4H) and b* p(b|4H), i.e. multiply a or b with the probability that partner would bid 4H with such a hand. This is a fact, and there is no point discussing it. I occasionally find this way of estimating probabilities useful, and maybe Mike will never find it useful.

Anyway, let's say partner is 3=0=4=6. His diamonds will probably by very good (because we have most of the bad diamonds). His clubs will probably be so-so only (he lacks the A and typically one or two of KQJ). He should expect preemptor's partner to jump to 4♥ most of the time (who is more likely to have 4 hearts, the unbalanced 1♦ opener or his LHO?). He can't expect a delicate auction, and I think he should jump to 4♥ quite often. Our agreement (void!) is already quite specific, and there is little point in reserving it for the perfect hand (0=5 in the red suits with 10-12 hcp and a second round control in each black suit??).

[gnasher]

Partner had Axx - KQ10xxx KQJx. I signed off in 5♦, but he bid 6♦ anyway, on the grounds that I was likely to have an ace. (We've subsequently agreed that if he thought he was worth a slam-drive he should have followed a different route - he could have bid 3♥ showing shortage, followed by 4♣ to initiate cue-bidding.)

At the time, I thought it was fairly clear to sign off. Partner's 4♥ directs my attention to non-heart cards, of which I have an ace and a jack. ♥AK will be useful opposite some specific spade holdings, but there's no reason to believe that partner has one of those.

In particular, I don't think we can infer that he has fewer than four spades. If he were 4045 or 4054, there would be no benefit to playing in spades, and it would risk a bad trump break or a diamond ruff. A negative double might lead to a stupid result defending 2♥x, and it might be hard for him to show his diamond support later.

[benlessard]

gnasher, on 2011-July-28, 02:02, said:

Partner had Axx - KQ10xxx KQJx. I signed off in 5♦, but he bid 6♦ anyway, on the grounds that I was likely to have an ace. (We've subsequently agreed that if he thought he was worth a slam-drive he should have followed a different route - he could have bid 3♥ showing shortage, followed by 4♣ to initiate cue-bidding.)

Im not sure I see how its going to help ? IMO In the end you will just have a bigger guess to make. Also im curious how come 3H show shortness, I would bid 3H with 3253,3244 shapes rather than makig a neg X or a 3C response.

[aguahombre]

Amusing. And confirming that the whole thing was a matter of context and style (number of diamonds guaranteed by the opening bid).

Those who believed in the likelihood that responder's shape was pretty-much exactly what it was were wrong, because responder should have bid it differently with exactly what he had??

Those who signed off in 5D were right, because if responder had what the others thought he had --responder would bid 6 anyway.

Would Responder have assumed the two useful heart tricks and absolute club control with a lesser club holding has well and still bid 6?

[cherdano]

benlessard, on 2011-July-28, 08:44, said:

Im not sure I see how its going to help ? IMO In the end you will just have a bigger guess to make. Also im curious how come 3H show shortness, I would bid 3H with 3253,3244 shapes rather than makig a neg X or a 3C response.

I wrote earlier in the thread that when Mike makes a post about legal issues, I start by assuming he knows what he is talking about. I would recommend the same with posts by gnasher about bridge.

My guess would be that a partnership that knows that 4H shows a void rather than unspecified heart shortness has very specific agreements on this auction. (My guess: 2N is natural, perhaps with transfers, so that 3♥ isn't needed for an arbitrary forcing raise.)

[gnasher]

benlessard, on 2011-July-28, 08:44, said:

Im not sure I see how its going to help ? IMO In the end you will just have a bigger guess to make.

On the actual hand, it would have gone

1♦-(2♥)-3♥
3NT-4♣
4♥-4♠

and opener might take control with 4NT, or he might bid 5♣ after which responder would bid slam.

The point is that 3♥ allows room for opener to show a lack of enthusiasm, and then responder to say "I'm still interested". The 4♥ bid in our actual auction left opener guessing whether his hand was good enough to justify a cue-bid.

Quote

Also im curious how come 3H show shortness, I would bid 3H with 3253,3244 shapes rather than makig a neg X or a 3C response.

We play transfers:

2NT = clubs
3♣ = diamonds, competitive or game-forcing
3♦ = diamonds, invitational
3♥ = splinter

[aguahombre]

gnasher, on 2011-July-28, 10:00, said:

We play transfers:

2NT = clubs
3♣ = diamonds, competitive or game-forcing
3♦ = diamonds, invitational
3♥ = splinter

Just a thought: maybe it would be better to incorporate 2 ways of showing four spades (the neg double which might be left in, and another which cannot), perhaps at the expense of 2 ways of showing heart shortness (singleton vs. void). The alternate way would imply extreme heart shortness by inference, anyway.


Or maybe not

[Fluffy]

even if that was true you don't want to have specific agreements for each uncommon sequence

[nige1]

gnasher, on 2011-July-28, 02:02, said:

Partner had Axx - KQ10xxx KQJx. I signed off in 5♦, but he bid 6♦ anyway, on the grounds that I was likely to have an ace. (We've subsequently agreed that if he thought he was worth a slam-drive he should have followed a different route - he could have bid 3♥ showing shortage, followed by 4♣ to initiate cue-bidding.)

As usual it's just judgement and luck. Although gnasher's 5♦ works opposite partner's actual hand, if partner has a suitable weaker hand such as ...
♠ Axx ♥- ♦ KQxxxx ♣ Qxxx, then a 5♣ cue might be needed to stir him into action..

[jallerton]

aguahombre, on 2011-July-28, 10:12, said:

Just a thought: maybe it would be better to incorporate 2 ways of showing four spades (the neg double which might be left in, and another which cannot), perhaps at the expense of 2 ways of showing heart shortness (singleton vs. void). The alternate way would imply extreme heart shortness by inference, anyway.

Or maybe not

"maybe not" is correct.

There is not much room available in this sequence, so you if use an extra bid for something, you have to say which other bid you are giving up.

If partner has 4 spades with "extreme shortness" in hearts then he will usually either be able to raise diamonds or will have a sufficiently long club suit to treat the hand as a single suiter in clubs.

[MrAce]

aguahombre, on 2011-July-28, 10:12, said:

Just a thought: maybe it would be better to incorporate 2 ways of showing four spades (the neg double which might be left in, and another which cannot), perhaps at the expense of 2 ways of showing heart shortness (singleton vs. void). The alternate way would imply extreme heart shortness by inference, anyway.


Or maybe not

He can transfer to a suit and then bid ♠ with 4 card ♠ hands that he doesnt want the DBL to be converted, no ? Because a hand that doesn't want a conversion with only 4♠, will always have a huge side suit or a 3 suiter. And he doesn't have to sacrificie on 2 ways of showing ♥ shortness. Unless i am missing something.

[aguahombre]

No, you are not missing something. His transfer scheme could handle that and leave no doubt that the jump of 4H, in addition to showing a void denies 4S and has more than 4D.

[Tataie]

Close but 5♦ for me..
1. bad trumps ..6th is a +
2. too much on ♥ still AK is a +
3. Nothing on ♠ => Horrible
4. 2kc = neutral

[jogs]

Cyberyeti, on 2011-July-25, 06:28, said:

In style do you cue bid after 4♥ with a minimum, or does it show extras ? And what's your cue bidding style ?

5♣ has the virtue of denying a spade control (and I'm much happier doing this if playing a 1sts and 2nds cueing style so I'm denying the K too.)

Partner can be as good as QJ10x, -, AKQxx, KQJx and you may not be able to make 5 with the spade ruff let alone 6, and need to play in no trumps.

I think I'd probably bid 5♣ as blackwood doesn't tell me what I need to know.

For the reasons given by you, bid just 5♦. If pard has the ♠A and ace king of diamonds, he still needs tricks to make 12 tricks in diamonds. With that much he may find a call over 5♦.

[aguahombre]

Following the thread a little more closely, we find that he doesn't need even the AK of diamonds, and doesn't need any club spots. AXX - KQXXX XXXX was plenty.