execrable acbl bidding contest problems

[xcurt]

So your simulations indicate that with ♠QJxxxxx ♥AT ♦AJ ♣xx, you are making slam more than half the time on hands where opener would not move over the quantitative 4♠ invite?

My simulation suggests that if we bash slam we will make it 65% of the time assuming the opponents lead randomly from among the offsuits. That introduces a free parameter -- how good are the opponents on lead. This parameter has a dependence on our auction. The more information we transmit, the better they do. The 65% figure is across all hands.

 

I find this somewhat hard to believe. Surely with only 28 hcp between you or so, you could easily be off two aces or an ace and the trump king, or the club ace-king, etc.

 

This is measurable. I measured it. Partner has at least three of the CA, CK, SA, SK 85% of the time. That's from a simulation with a million hands generated including roughly 40,000 where partner has the strong NT.

 

 

My count is, over 30 hands:

 

6♠ cold: 4

6♠ better than a finesse, not cold: 4

6♠ on a finesse: 5

6♠ worse than a finesse but some play: 11

6♠ no play: 6

 

This suggests that blasting 6♠ may well lead to going down more than it leads to making. If we assume that the quantitative approach bids the "better half" of the slams you can see that it's a huge winner over blasting slam. More realistically, even if the quantitative approach just keeps you out of the "no play" slams and randomly gets you to slam on half the other hands, it seems substantially better than blasting.

 

It matters here what "better than a finesse" and "worse than a finesse" and "no play" mean. No play might mean no play if they cash the CAK. I had a few where if they don't cash we are anywhere from a favorite to make 6, to cold for 13 tricks. There are a few that are 5/7 or 4/7 hands now. Again, the free parameter about how the opponents might lead. You have to put percentages on making and then compute the expectation over all the outcomes times the probability of each outcome to arrive at a net expectation for just bidding slam.

 

This suggests that blasting 6♠ may well lead to going down more than it leads to making. If we assume that the quantitative approach bids the "better half" of the slams you can see that it's a huge winner over blasting slam. More realistically, even if the quantitative approach just keeps you out of the "no play" slams and randomly gets you to slam on half the other hands, it seems substantially better than blasting.

 

Computing the expectation for bashing versus 2H...4S introduces a second free parameter, which is how often partner will move over the latter action by responder. I don't have a copy of bridge browser handy so I will just take a guess based on my experience that in real life it's between 30% and 40%. For computing the expectation of 2H... 4S we also need to add in the unbid slams when opener is passing and slam is still good.

 

I computed the relative expectation of the two bidding plans as a function of my simulation results and various values for the free parameters. I probably underestimated the chances of the opponents finding the correct lead when their choice matters, but I probably overestimated the chances partner would move over 4S. Reasonable people might disagree on the results and I didn't mean to present them as absolute. This all got away from my original point which is that the bidding problem is really just not a good bidding problem. I could have done a better job making myself clear in my original post and I apologize for that.

[ArtK78]

I admit I did not have the time (or the inclination) to read all of the foregoing posts carefully. But the idea that opposite a random strong 1NT opening that the 7222 hand would make 6♠ 80% of the time (or 65% of the time, or whatever number you finally wound up with) deserves a special comment (aside from the fact that I disagree with that assessment).

 

Is there some reason why we can't try to determine logically whether this is one of the 20% of the hands that will not make 6♠?

 

In addition, much of the discussion reminded me of a tournament recap that I am sure that I mentioned once or twice previously. In one of Edgar Kaplan's Bridge World recaps of a major tournament (it may have been a U.S. team trials) he commented about one hand in this manner: "Expert A appears to have doubled the opponents' 5♠ bid on the theory that on any given hand it is unlikely that the opponents can make 11 tricks in spades. Unluckily for Expert A, this was one of those hands."

[hrothgar]

I find this somewhat hard to believe. Surely with only 28 hcp between you or so, you could easily be off two aces or an ace and the trump king, or the club ace-king, etc.

 

This is measurable. I measured it. Partner has at least three of the CA, CK, SA, SK 85% of the time. That's from a simulation with a million hands generated including roughly 40,000 where partner has the strong NT.

Once again, I'd like to request that people who claim results based on simulations provide a copy of their code so that we can evaluate whether they know what they are talking about.

 

For example, here is a very simple script designed to measure Foo's claim

 

predeal

 

north SQJ87543, HAT, DAJ, C32

 

controls = hascard(south, AC) + hascard(south,KC) + hascard(south, AS) + hascard(south, KS)

 

condition

 

shape(south, any 4432, any 5332, any 4333) and

hcp(south) >= 15 and

hcp(south) <= 17

 

action

 

frequency (controls, 0, 4)

 

I readily admit that the definition a 1NT opening by South is quite loose. However, the main change that I'd add would be upgrading good 14 counts which would only decrease the control count.

 

Moreover, I haven't considered the opponent's pass which would modify the results (slightly). None-the-less, I find the results illuminating

 

Controls

0 Controls = 0%

1 Control = 2.9%

2 Controls = 41%

3 Controls = 50.1%

4 Controls = 5.9%

 

My sim says that Partner has a least three of the key controls about 56% of the time. There seems to be some inconsistency between our results.

 

Notice the convenience of being able to verify my methods...

Some would claim that this effects the credibility of my statement

[jdonn]

My simulation suggests that if we bash slam we will make it 65% of the time assuming the opponents lead randomly from among the offsuits.  That introduces a free parameter -- how good are the opponents on lead.  This parameter has a dependence on our auction.  The more information we transmit, the better they do.  The 65% figure is across all hands.

Wouldn't this strongly support making a slam TRY, as if partner accepts on about half of his hands you will make slam 100% of the time you bid it and 30% of the time you don't? I realize the correlation isn't absolutely as direct as that between partner's judgment and slam making, but it's obviously very strong so the conclusion should be the same.

[xcurt]

...

You're correct and again I apologize for not being precise enough in my previous posts. I should have said "partner has two or more key cards," not "partner has 2 or more key cards and 3 of the 5 key cards and CK," at least 85% of the time. You also make a good point about code so here is the code to check. I'll try to post code for simulations when I do them.

 

# enough keys => we have 4 or 5 key cards between the NS hands

# clubs controlled => partner has at least one of the CA or the CK

# slam biddable => both of (enough keys) and (clubs controlled)

 

predeal

 

north SQJ87543, HAT, DAJ, C32

 

keys = hascard(south, AS)+hascard(south, KS)+hascard(south,AC)

enough_keys = keys>=2

clubs_controlled = hascard(south, AC) || hascard(south, KC)

slam_biddable = enough_keys && clubs_controlled

 

condition

 

shape(south, any 4432, any 5332, any 4333) and

hcp(south) >= 15 and

hcp(south) <= 17

 

action

 

average "enough keys" enough_keys,

average "clubs controlled" clubs_controlled,

average "slam biddable" slam_biddable

 

enough keys: 0.846463

clubs controlled: 0.882205slam biddable: 0.751074

Generated 1000000 hands, produced 33295.

 

But, we will make slam a fair bit of the time when clubs are open if the opponents lead poorly. So I'll stand by my conclusion that the overall expectancy of bashing is higher than 2H... 4S.

[xcurt]

My simulation suggests that if we bash slam we will make it 65% of the time assuming the opponents lead randomly from among the offsuits.  That introduces a free parameter -- how good are the opponents on lead.  This parameter has a dependence on our auction.  The more information we transmit, the better they do.  The 65% figure is across all hands.

Wouldn't this strongly support making a slam TRY, as if partner accepts on about half of his hands you will make slam 100% of the time you bid it and 30% of the time you don't? I realize the correlation isn't absolutely as direct as that between partner's judgment and slam making, but it's obviously very strong so the conclusion should be the same.

Yes but which slam try? The point I'm arguing, poorly (and that's good reason not to post at 12:30 am local or during lunch at the office), is that we should never have bid 2H... 4S since the simple bashing auction is already better expectancy.

 

Which bidding plan would you pick over a strong NT?

 

(a) sign off in game

(b) 2H...4S

© 2H...3C

(d) 2H...3D

(e) 2H-2S-6S

(f) 6S

(g) Stayman (followed by what?)

(h) other (what?)

 

We already know (a) is hopeless. I'm arguing that (e) is better than (b).* I expect (e) is better than (f) but I haven't tested it. (g) seems hopeless since we don't have a way to force in spades now and the information we get won't help. I have a sneaking admiration for plan © but I would probably choose (d) at the table.

 

*Unless partner is a madman who makes a forward-going move 65% of the time.

[awm]

My simulations indicate that signing off in game is probably better than signing off in slam. If anyone really wants to see my C code, I can send it to them -- I am not using the same dealing software that seems to be the rage these days. Certainly if opponents always make the right leads, it is not even close and signing off in game is dramatically better than signing off in slam.

 

While there are always opportunities for opponents to make truly awful leads, in most cases a passive lead against 6♠ doesn't cost on these hands. If we assume that opponents lead from small cards where possible (i.e. don't lead away from their club king into declarer's AQ or bang down the spade ace felling partner's singleton king) then signing off in game still looks like a winner over signing off in slam, albeit by a bit less.

 

Anyways, regardless of what the "right" answer might be, isn't the fact that this hand generates so much debate an indication that it was in fact a good problem hand?