math or simulation for this

[Fluffy]

I open 1NT 14-16 with

 

♠AQJ

♥J93

♦KQ108

♣J64

 

 

Partner bids 2♣-2♦-2♥ showing at least 5-4 in the majors and a weak hand (less than 9)

 

Will partner have more hearts or spades on average?

[Vampyr]

I open 1NT 14-16 with

 

♠AQJ

♥J93

♦KQ108

♣J64

 

 

Partner bids 2♣-2♦-2♥ showing at least 5-4 in the majors and a weak hand (less than 9)

 

Will partner have more hearts or spades on average?

 

Hearts, I think, because if the spades are any good partner might have bid 2♠ over 2♦ (if available) or transferred initially.

 

EDIT: similarly, if the default is to bid rebid hearts with 3-3, then with 4-5 partner is guaranteed to find an 8-card fit if there is one. With 5-4 there is no such guarantee, so less of a reason to keep hearts in the picture.

[PhilKing]

I can think of 2 reasons for "more hearts" off the top of my head, but none for "more spades" yet.

[Jinksy]

What would be the parameters of the simulation?

 

My guess would be ♥s, since if he had 4, there's a chance opps would have overcalled in the suit, which looks much less likely in ♠s.

[mgoetze]

partner might have bid 2♠ over 2♦ (if available)

Really can't even begin to answer this question without knowing what other options partner had (for me 2♥ would have shown much the same but 2♠ would have been invitational with 5 spades).

[gszes]

Idealistically partner is using the system to best advantage, that means

they will not use this particular system with 4 lousy hearts and 5 lousy spades

vastly preferring to transfer to spades in that situation since it is quite

risky taking a chance on playing a lousy 7 card heart fit and missing a lousy

8 card spade fit. Responder will have no qualms with 4 lousy spades and 5 lousy

hearts since there is no risk of missing the 8 card heart fit.

 

Hearts should have 5 more frequently than spades but how often is a matter of

personal taste. Where would you draw the line between a simple transfer and

using stayman with the following hands?

 

AKQ2 87654 32 32

AK32 87654 32 32

AQ32 87654 32 32

QJT2 87654 32 32

 

and will your answer depend on vulnerability?

[whereagles]

If the bid can be 0 hcp, then the odds are exactly the same. If some hcp are required for it, then perhaps hearts are more likely, but the difference will always be infinitesimal.

 

Probably the real question is "should I keep playing this system?", to which I would firmly say "no". http://www.bridgebase.com/forums/public/style_emoticons/default/cool.gif

[Radrag]

I open 1NT 14-16 with

 

♠AQJ

♥J93

♦KQ108

♣J64

 

 

Partner bids 2♣-2♦-2♥ showing at least 5-4 in the majors and a weak hand (less than 9)

 

Will partner have more hearts or spades on average?

 

I'm assuming that partner will bid like this EVERY time he has 54+ in the majors and less than 9.

 

There are more unknown x's in spades, so there are more ways to construct a weak hand with 5(+)spades than 5(+)hearts.

[Radrag]

If the bid can be 0 hcp, then the odds are exactly the same.

 

The fewer hcp partner has the more likely spades are longer than hearts.

[jogs]

Question: does partner ever transfer with 5=4 or 4=5?

 

If not, both patterns are equally likely.

[Fluffy]

What would be the parameters of the simulation?

 

 

at least 5-4 in the majors and a weak hand (less than 9)

You can discount 6-4, 7-5 and 7-4 I guess but I don't think they are going to change which suit is longer if any.

[suokko]

I have agreement that biding promises more spades than hearts. We transfer to hearts with a weak hand and 5 hearts and 4 spades. Only mildly invitational with 5 hearts and 4 spades bids stayman. So this question is more about agreement details than actual random parameters.

 

But simulation shows:

$ cat simu.descr 
predeal north SAQJ,HJ93,DKQT8,CJ64

condition shape(south, 54xx + 45xx + 55xx) && hcp(south) < 9

action
frequency "heart length" (hearts(south),4,5),
frequency "spade length" (spades(south),4,5),
$ ./dealer < simu.descr 
Frequency heart length:
   4	  140195
   5	  164470
Frequency spade length:
   4	  124103
   5	  180562
Generated 10000000 hands
Produced 304665 hands
Initial random seed 1419266048
Time needed    3.185 sec

 

So more small cards in spades makes spade length more likely because of hcp limits.

[PhilKing]

I have agreement that biding promises more spades than hearts. We transfer to hearts with a weak hand and 5 hearts and 4 spades. Only mildly invitational with 5 hearts and 4 spades bids stayman. So this question is more about agreement details than actual random parameters.

 

But simulation shows:

$ cat simu.descr 
predeal north SAQJ,HJ93,DKQT8,CJ64

condition shape(south, 54xx + 45xx + 55xx) && hcp(south) < 9

action
frequency "heart length" (hearts(south),4,5),
frequency "spade length" (spades(south),4,5),
$ ./dealer < simu.descr 
Frequency heart length:
   4	  140195
   5	  164470
Frequency spade length:
   4	  124103
   5	  180562
Generated 10000000 hands
Produced 304665 hands
Initial random seed 1419266048
Time needed    3.185 sec

 

So more small cards in spades makes spade length more likely because of hcp limits.

 

Were this the only variable factor, it would be a slam dunk.

 

However, it ignores the opponent's bidding. With a borderline hand, depending on methods, an opponent would be more likely to enter the bidding with a chunky 4 card major plus a 5-card minor, for instance. And they can't only have a chunky major if it is hearts. The argument also holds with 5M4m hands.

 

Also, assuming OP plays Stayman followed by 2♠ as invitational with five, there is a gap when holding the equivalent hand with 9 points and 45 in the majors. It is quite rational to go low and bid Stayman followed by 2♥ with that agreement.

 

Having said all that, my gut instinct is that the spade blockers trump my arguments.

[suokko]

Were this the only variable factor, it would be a slam dunk.

 

However, it ignores the opponent's bidding. With a borderline hand, depending on methods, an opponent would be more likely to enter the bidding with a chunky 4 card major plus a 5-card minor, for instance. And they can't only have a chunky major if it is hearts. The argument also holds with 5M4m hands.

 

Also, assuming OP plays Stayman followed by 2♠ as invitational with five, there is a gap when holding the equivalent hand with 9 points and 45 in the majors. It is quite rational to go low and bid Stayman followed by 2♥ with that agreement.

 

Having said all that, my gut instinct is that the spade blockers trump my arguments.

 

I never even try to make perfect simulation that takes all unlikely parameters into account. To me opponents passing in this situation is balanced enough effect to both lengths. It would probably have more effect to hcp frequency for south making the lowest values less likely. Of course that reduces slightly spade blockers effect but it isn't going to reverse the effect.

[benlessard]

A more important question is ..is it ok to do Garbage stayman with both 54 and 45 ? or should you transfer with one shape but not the other.

 

Also responder pts matter here, with some values like 6-8 pts maybe he can play it safe and transfer knowing 2M in a 5-2 fit is less likely to go down, the main fear would be to avoid the 4-3. The cost of missing the 4-4 is lower. With a weaker hand however aiming for the 4-4 fit has more upside since it could be your only hope to get a plus score.

 

Also maybe with (54)22, 6-8 pts and poor majors maybe passing 1NT is the percentage call at imps if you play GS as 54 or 45.

[The_Badger]

hi Fluffy,

 

As I know a fair amount about statistics and computers I will provide you with an analogy. I bought a lucky dip lottery ticket once and the computer-generated ticket was 6 consecutive numbers! The point I'm making is that simulations are only that, they cannot compete with raw statistics. I was very unlikely to ever win with that ticket BUT it is one of the 14 or so million combinations of numbers that are available, so it actually stands just as much chance as any other ticket in theory.

 

If you partner ALWAYS bids 2♣ with any 5-4 majors of less than 9 points, and does not deviate from that premise, whatever cards and honour cards he holds, there is an equal chance of him holding 5♥/4♠ or 4♥5♠.

 

However, if he has AN ADDITIONAL OPTION to make a major suit transfer if he has honour cards in a suit, then he is more likely to have a 5 card ♠ suit on probabilities.

[Free]

In my partnership ♠s are longer or equal in length to ♥s. With 5♥-4♠ we transfer to ♥ and hope we didn't miss a better ♠ fit. This way opener should always correct to 2♠ after the above auction and know it's the best action for sure.

 

You can play the other way around for sure, for example if you think it's better that the weak hand declares (unknown strength).

 

Without such agreement, chances are equal.

[PhilKing]

 

 

If you partner ALWAYS bids 2♣ with any 5-4 majors of less than 9 points, and does not deviate from that premise, whatever cards and honour cards he holds, there is an equal chance of him holding 5♥/4♠ or 4♥5♠.

 

This statement is "true", but it is not true when we hold this hand for the reason given by Radrag and Suokkoi.

 

There are more combinations of weak hands containing 5 spades than there are holding 5 hearts. In a word, "blockers". If you don't trust simulations you can do it this way - put the missing cards in three piles: spades, hearts and minors. Then deal four cards from each pile then mix the remaing major cards and deal one card. You will find more heart hands invalidated for being too strong than vice versa.

[SixOfWands]

I open 1NT 14-16 with

 

♠AQJ

♥J93

♦KQ108

♣J64

 

 

Partner bids 2♣-2♦-2♥ showing at least 5-4 in the majors and a weak hand (less than 9)

 

Will partner have more hearts or spades on average?

 

If you're playing a weak version of Stayman where you can bid 2C with 54 in the majors (either suit longer) then you should always bid your five card major on this sequence.

 

1NT - 2C - 2D - 2H should promise five+ hearts.

 

Partner does not have a four card major and a 5-2 fit plays better than a 4-3 fit. You might still have a fit in your five card major but you definitely don't in your four card suit. So just agree to bid the longer one, its simple if you do that. This is the standard approach in the UK.

[PhantomSac]

If you're playing a weak version of Stayman where you can bid 2C with 54 in the majors (either suit longer) then you should always bid your five card major on this sequence.

 

1NT - 2C - 2D - 2H should promise five+ hearts.

 

Partner does not have a four card major and a 5-2 fit plays better than a 4-3 fit. You might still have a fit in your five card major but you definitely don't in your four card suit. So just agree to bid the longer one, its simple if you do that. This is the standard approach in the UK.

 

Obviously if you can bid 2S showing 5S and 4H weak you don't need to play this way. Some people use 2C then 2S as something more important than that hand type and sacrifice accuracy on weak 5/4 hands for gains on others.

[PhantomSac]

@Fluffy, I think it's just better to have an agreement as to what opener is going to do with 3-3. I believe Fred and Brad play opener always corrects to 2S, so with 5 good hearts and 4 bad spades you would just transfer to hearts and take your chances. Most people do the opposite (so with 5 good spades and 4 weak hearts you transfer to spades and take your chances). I think this is better than opener always deciding in the moment what to do with 3-3, you get to the better fit more often if it is already pre-determined what opener does so that responder can adjust accordingly sometimes. Of course no matter what sometimes you will end in the wrong fit. Another thing is you don't want to be tanking on whether to pass or correct every time, it gives away to the defense that you are 3-3 which is very bad.

[Jinksy]

I tried bidding several random BBO hands where 1N 2C / 2D 2H could be on 4-4 or 5-4 (or 5-5) in H/S, and at least opposite a weak NT, I found that it was a huge winner over requiring 5-4.

 

The goal was to free up 1N 2C / 2D 2S as inv with exactly 4Hs, 5Ss, but I ended up finding - again, emphasis opposite a weak NT - that it was a much bigger gain playing that the old way - 4Hs, 5Ss, weak takeout.

 

I want to try the latter one more time, possibly later tonight, but from the few dozen hands I bid, the results were overwhelmingly in favour of the 2H-could-be-4-4, and strongly in favour of the 2S-weak meanings (ironic, given that the former was supposed to be a sacrifice to enable something different for the latter). I'll report back if I do, but atm I feel pretty confident that the UK standard approach is a poor one (given that it's generally played with weak NT).

[PhilKing]

I tried bidding several random BBO hands where 1N 2C / 2D 2H could be on 4-4 or 5-4 (or 5-5) in H/S, and at least opposite a weak NT, I found that it was a huge winner over requiring 5-4.

 

The goal was to free up 1N 2C / 2D 2S as inv with exactly 4Hs, 5Ss, but I ended up finding - again, emphasis opposite a weak NT - that it was a much bigger gain playing that the old way - 4Hs, 5Ss, weak takeout.

 

I want to try this one more time, possibly later tonight, but from the few dozen hands I bid, the results were overwhelmingly in favour of the 2H meaning, and strongly in favour of the 2S meaning. I'll report back if I do, but atm I feel pretty confident that the UK standard approach is a poor one (given that it's generally played with weak NT).

 

A lot of UK players of my acquaintance play 2♣ then 2♠ as inv with 5 spades, regardless of the heart holding, but that is irrelevant to this thread.

[PhantomSac]

A lot of UK players of my acquaintance play 2♣ then 2♠ as inv with 5 spades, regardless of the heart holding, but that is irrelevant to this thread.

 

Ya ditto

[Jinksy]

Hadn't seen that before. I dunno if people will be interested, since this is all quite subjective, but I've just tried a number of hands (around 70 including redeals, at a rough guess) on BBO where opener had a balanced 12-14*, and responder had either 5S 4H 0-12 points or 5Ss 0-4H and 10-12 points.

 

I discarded all hands where it seemed to make no difference (ie you'd end up in the same contract in each system), which introduces a very slight bias in favour of Phil's method above, since rightsiding the contract toward the stronger hand (via the alternative of xferring then bidding 2N) looked worth very roughly 1/10th of a trick whenever it came up.

 

I don't know how to share the hands atm, but I'll save them all and, if anyone's interested, upload what look like the key hands. My analysis is fairly superficial crypto-DD, based on a combination of what GiB can make in the contracts I let it judge (I can't rewind and check it on other when I bid from a teaching table, which I find otherwise much easier) and about 60 secs per board of looking at the outcome of the best DD play I could find. That said, if I saw an obvious example of DD play making a significant difference for one contract and not the other, I'd note it.

 

Testing the three meanings for 1N 2C / 2D 2S - a) 'any invite with 5Ss and 0-4Hs', b) 'invite with 5Ss and 4Hs', and c) 'weak takeout with 5Ss and 4Hs' - I'll skim through the hands again now and try and give a rough account. I'm assuming if playing a) or b), c-type hands bid Stayman then 2H unless the S suit was significantly better. This let's you find more 4-4s at the expense of playing in more Moyesians when there's a 5-2 (and, rarely, a 5-3) available, which seems like a decent tradeoff, but YMMV (if I do this again, I'll try having these hands just xfer to Ss, and see if I get noticeably different results).

 

In a), if opener had a poor S holding, I corrected to 2N, so when it came up, it could normally only make a difference if you made in 2S vs going off in 3S, or made an extra trick in 2S when opener didn't correct to 2n but would have passed it. (On most hands that followed this sequence, opener did have a poor S holding, so while it came up quite frequently, it made a difference on relatively few occaions). It might also matter if with a highly distributional hand you got to make an inv 2S bid (subsequently accepted) where you'd otherwise have given up on game and settled for a weak 2S bid, but this didn't come up.

 

a)

1 overtrick saved (in 2S vs 2N) x1

 

b)

This only came up once, and I accidentally hit redeal before I could read it out.

 

c)

1 undertrick saved x4

2 undertricks saved x1

1 overtrick saved x2

Part score saved (ie 2S making, 2H going off, and other methods end you in the latter) x2

 

* 'balanced' may be 22(54), which was key on a couple of the deals c) gained over/undertricks on, so if you prefer to open those 1m, downgrade c) appropriately.

 

I think in retrospect it might be a mistake to start with Stayman on 5S4H hands when not playing c), so I'd like to revisit this. Still it seems like c) is fairly dominant for the weak NT. Last caveat is that this fit with my prior expectations, so I've probably suffered some bias in my evaluations - would be interested to hear if a proponent of a) (or b, though I doubt it) has tried something similar and had different results.