[Statto]

 HighLow21, on 2012-March-25, 16:40, said:

In order of preference, roughly, are the following holdings in RHO's opening bid suit, in terms of whether to overcall:
- 5+ with A or no honors at all
...

One reason to overcall with the longer holdings is hoping to push opps up a level then sit back and defend.

 HighLow21, on 2012-March-25, 16:40, said:

With less and less length in opener's suit, a stronger overcall suit is more essential, because more shortness in the opening suit decreases the likelihood of partner having fitting length and/or strength. (It also increases the chance of partner having wastage in the opening suit.)

Partner is just as likely to have a fit regardless of your length in RHO's suit. Mike Lawrence if he said otherwise is wrong here. However I agree with the point about it being more likely partner has wastage in the suit.

Having shortage in openers suit has other advantages. Or put another way, having length in the other suits has advantages. If partner bids her own 5-card suit, she's more likely to find your hand fitting.

[HighLow21]

 655321, on 2012-March-25, 16:55, said:

I admit I would always overcall the first hand NV, but vulnerable it doesn't seem quite as clear to me.

And the second example, although it is not a terrific hand, I would always overcall 2♣ even when vulnerable.

So I don't agree with your rankings.

Try searching the forums for replies to this one.

What am I to search on, and what am I going to find that negates the award-winning writings of a world champion? Besides, simple mathematical logic dictates that he is correct.

We are entitled to different opinions, but one thing is clear. Hand example #1 is a far safer overcall than hand example #2. Example #2 may have more offensive potential, but it's also the only one of the two that can get tagged for a telephone number.

And safety in overcalling is the gist of this forum thread.

[Statto]

 HighLow21, on 2012-March-25, 16:53, said:

If partner has fewer diamonds, he has more non-diamonds. Therefore, more likely, he has some number of clubs. When he has 2 diamonds (as here, about average in this spot), his expectation is slightly more than 3 clubs. Voila: a sufficient trump suit.

No, there are still the same number of unaccounted-for non-club cards in the mix, it makes no difference. Think about it...

[HighLow21]

 Statto, on 2012-March-25, 17:06, said:

One reason to overcall with the longer holdings is hoping to push opps up a level then sit back and defend.

And how do you feel if they have a great fit elsewhere, and so do you?

 Statto, on 2012-March-25, 17:06, said:

Partner is just as likely to have a fit regardless of your length in RHO's suit.

Demonstrably false.

Not only do length AND shortness in RHO's suit decrease the off-the-top losers expected in that suit, but length in RHO's suit decreases partner's likely length in that suit and, therefore, on an expectation basis, the number of cards he holds in any other suit.

 Statto, on 2012-March-25, 17:06, said:

Mike Lawrence if he said otherwise is wrong here.

You've just totally invalidated your argument. You're right: he has 3 world titles, logic, and Bayesian mathematics ALL backing his statements. What on earth was I thinking??

 Statto, on 2012-March-25, 17:06, said:

Having shortage in openers suit has other advantages. Or put another way, having length in the other suits has advantages. If partner bids her own 5-card suit, she's more likely to find your hand fitting.

Yes, having shortage is just as good in some ways as having length; it's worse in some ways; and it's better in some ways. The main point is, 3 cards is horrible, and movement in either direction is beneficial. That said, one way shortness is worse is this: if your suit does become the trump suit, your partner will, on average, have less support than if you had length on opener's bid suit; and you will thus be subject to early tapping more often.

[Statto]

 HighLow21, on 2012-March-25, 17:08, said:

the award-winning writings of a world champion?

These writers try to explain their judgement in layman's terms, and sometimes they get it wrong. Besides, some of them are trying to make a buck or two, because professional bridge doesn't exist.

Quote

Besides, simple mathematical logic dictates that he is correct.

No, it shows he is wrong in one aspect.

[HighLow21]

 Statto, on 2012-March-25, 17:11, said:

No, there are still the same number of unaccounted-for non-club cards in the mix, it makes no difference. Think about it...

Yes, but that is only one part of the calculation: the number of non-club cards in the mix.

The other part of the equation is the expected number of non-diamond cards in partner's hand, and as that number goes up, so does the expected number of clubs. (And so does the expected number of spades and hearts!)

[HighLow21]

 Statto, on 2012-March-25, 17:18, said:

These writers try to explain their judgement in layman's terms, and sometimes they get it wrong. Besides, some of them are trying to make a buck or two, because professional bridge doesn't exist.

Mike Lawrence is a 3-time world champion, a member of the Bridge Hall of Fame, and one of the all-time leading masterpoints winners. His book on overcalls is considered one of the top two or three texts in history on the subject, and when it was written in 1980, is was THE authoritative book on the subject.

 Statto, on 2012-March-25, 17:18, said:

No, it shows he is wrong in one aspect.

I can show you that he is correct with a mathematical proof if you prefer.

[Statto]

 HighLow21, on 2012-March-25, 17:17, said:

Demonstrably false.

... length in RHO's suit decreases partner's likely length in that suit and, therefore, on an expectation basis, the number of cards he holds in any other suit.

Please demonstrate then. I would like to see how this flawed analysis holds up.

[655321]

 HighLow21, on 2012-March-25, 17:08, said:

What am I to search on, and what am I going to find that negates the award-winning writings of a world champion? Besides, simple mathematical logic dictates that he is correct.

Well I don't know, I tried searching on +Lawrence + overcall +length, you might be able to think of other search terms.

This post gives results of a simulation:
http://www.bridgebas...460#entry207460

The thread itself has posts ranging from intelligent discussion right down to jtfanclub posts.

[hrothgar]

 HighLow21, on 2012-March-25, 17:22, said:

I can show you that he is correct with a mathematical proof if you prefer.

I'll see your proof and raise you a Monte Carlo simulation...

Changing the number of Diamonds in West's hand from three to four has negligible impact on East's club hold
I didn't bother with a formal significance test, but I doubt that there is a statistically significant relationship


one_diamond =

spades(south) < 5 and
hearts(south) < 5 and

(
(diamonds(south) >=4 and diamonds(south) >= clubs(south))

or

(diamonds(south) == 3 and clubs(south) == 2)
)


two_clubs =

clubs(west) == 5 and
spades(west) <= 4 and
hearts(west) <= 4

condition

one_diamond and
two_clubs and
diamonds(west) == 3

action

average(clubs(east))

[Statto]

 hrothgar, on 2012-March-25, 18:22, said:

I'll see your proof and raise you a Monte Carlo simulation...

Changing the number of Diamonds in West's hand from three to four has negligible impact on East's club hold

Close, but try no effect. No simulation needed.

[HighLow21]

 Statto, on 2012-March-25, 17:25, said:

Please demonstrate then. I would like to see how this flawed analysis holds up.

Very well, just to keep it simple:

Assume opener has 4+ diamonds. I have 4 diamonds and 5 clubs, so ignoring my exact major suit layouts, this accounts for 13 of the cards. 39 are unknown, and partner has 13. Therefore on an expectation basis, partner has a 13/39 (1/3) claim to every unknown card.

The unknown cards are:
13 spades
13 hearts
5 diamonds
8 clubs

Partner has, on average:
13 x (1/3) = 13/3, or 4.3 spades.
13 x (1/3) = 13/3, or 4.3 hearts.
5 x (1/3) = 5/3, or 1.7 diamonds.
8 x (1/3) = 8/3, or 2.7 clubs.

On average, you usually have a club fit (if not at least club tolerance). It gets even better if you add a 5th diamond to your hand or opener's hand. Even if he only has 2 clubs, he may have a diamond ruffing value.

Now change your minor shape to 1-5. Now, there are 42 unknown cards, but they are 13 spades, 13 hearts, 8 diamonds, and 8 clubs.

Partner has, on average:
13 x (13/42) = 169/42, or 4.0 spades.
13 x (13/42) = 169/42, or 4.0 hearts.
8 x (13/42) = 104/42, or 2.5 diamonds.
8 x (13/42) = 104/42, or 2.5 clubs.

Now, partner only rates to have a club fit about half the time. In addition, just as often as not, dummy will be of no value for ruffing anything (in a club contract) and you may get tapped at trick 2. Granted a major suit fit is now more likely, but that offsets the decrease in the chance of a club fit. (Plus we can overcall in a major or takeout double with any hands having a 1-5 minor suit shape.)

I realize the difference is small, but the expectation of finding a fit a slightly more often, alongside the increased likelihood that the trumps can be used to ruff diamonds, is an important consideration.

[Statto]

 HighLow21, on 2012-March-25, 19:04, said:

Now change your minor shape to 1-5. Now, there are 42 unknown cards, but they are 13 spades, 13 hearts, 8 diamonds, and 8 clubs.

Um, how can there be 42 unknown cards? Are there 3 cards in my hand that I'm not allowed to look at?

Besides the 13 cards in my own hand which I know about, I also know RHO has some diamonds, maybe only 3, but that still limits it to 36 unknown cards in the first case, if we're just interested in distribution.

[jillybean]

LOL

I'm still sticking to my requirement for 6 decent clubs before I make a vulnerable 2 level overcall.

[the hog]

You do not need a solid suit to overcall. You just need a suit; this is not even a non vulnerable vs vulnerable overcall.

[neilkaz]

I am a big fan of aggressively overcalling 1♦ with 2♣ but here it goes too far, esp. when Red. The suit is weak enough that you often won't want it lead if LHO declares and while on BBO, weak opps never seem to catch someone for making a gargage bid like this, good opps will catch you and 2♣X making isn't game.

I commonly see people with this hand here but no Q♠..ie 10 hcp and the same rotten suit passing and then overcalling into a live unlimited auction. I passed PD's supX a month ago vs one of those opps who likes to pass and then o/c junk and racked up 1400.

I need a better suit than this to overcall at the 2 level vulnerable and certainly more tricks if things go badly.

.. neilkaz ..

[Statto]

 HighLow21, on 2012-March-25, 17:18, said:

The other part of the equation is the expected number of non-diamond cards in partner's hand, and as that number goes up, so does the expected number of clubs. (And so does the expected number of spades and hearts!)

It's simpler if you just stick to considering the non-♣ cards. Opener has some number of clubs. The remainder will be randomly distributed amongst the other 2 hands yet to bid. Whether your other cards are ♦ or ♥ or ♠ will not affect that.

[Cthulhu D]

This is actually a pretty interesting hand - the traveller would be a masterpiece played at the local club: Anyone else for a first in ekrens opening with east's hand? Or 5 hearts + another (which could be spades). I think I'd pre-empt with south's hand too, but he's lucky in that I think 2S played by south makes. This is going to be a swingy board.

Whoever sticks their neck out here is in big trouble.

[HighLow21]

 Statto, on 2012-March-25, 21:17, said:

It's simpler if you just stick to considering the non-♣ cards. Opener has some number of clubs. The remainder will be randomly distributed amongst the other 2 hands yet to bid. Whether your other cards are ♦ or ♥ or ♠ will not affect that.

Hmmmmm... you might be right about this and I apologize for being so forceful in my earlier posts. One thing, though, is that whatever club support (if 2+) likely to be more useful if partner is short diamonds.

I need to go think about this.

[MickyB]

My having diamond length reduces partner's expected diamond length.

Partner having short diamonds increases his expected club length.

However, just because

A implies B, and
B implies C

does not mean

A implies C