Bird/Anthias books on opening leads

[Vampyr]

3. Not letting partner know about your change in leading tendencies can throw the defence off. Talk to partner about the theory, particularly if you are going to stop leading 4th best from your long suits.

 

You seem to give short shrift to disclosure to the opponents.

[sfi]

You seem to give short shrift to disclosure to the opponents.

 

Not sure how you came to that conclusion. When was the last time you asked an opponent how likely they are to lead a short major against NT vs. a 5 card minor? What sort of an answer would you expect?

 

In any case, you can't have an agreement to disclose if you don't first talk about it with your partner.

[barmar]

Reading these books will probably also help your defense when playing in BBO robot tourneys. Their defensive strategy is based on DD simulations similar to that employed by the books (although far fewer hands are dealt, due to time constraints). Whenever someone complains "Why don't the robots return my suit when I lead 4th best against NT?", I refer them to the book, which suggests that these leads are not necessarily best. It tends to avoid leading away from honors, preferring to make a passive lead and hoping that partner will get in and find the killing switch.

[barmar]

You seem to give short shrift to disclosure to the opponents.

I don't think you have to disclose how you decide which suit to lead, that's just bridge judgement.

 

You have to disclose agreements about styles of leads, e.g. Rusinow versus top of an honor sequence, and 4th best versus 3rd/5th.

 

Note also that an agreement to lead 4th best doesn't mean that the lead of a low card promises at least 4 cards in the suit, or that you must lead from a 4-card suit. It just means that if you do have at least 4 in the suit you lead, you'll lead the 4th highest (unless you have a sequence at the top and you choose to make a sequence lead instead).

[awm]

Here are some possible data points which could refute this book (if they held):

 

1. Examine some set of hands from real play where the same contract was defended and different leads were made. Or do the same with "single dummy" simulation. Show that some leads perform consistently better/worse single dummy than they would double dummy.

 

2. Enumerate a set of situations where leads which do not cost double-dummy in fact help declarer at single dummy. Use a hand generator to show that these situations actually arise at a high level of frequency.

 

3. Analyze hands from top-level play to find examples where the defense dropped a trick subsequent to the opening lead. Show that this is quite common, and that it's more frequent on passive leads.

 

I haven't seen really serious attempts at any of the above. In fact I've seen analysis which suggests that 2 is not true (from the Bird/Anthias books in fact) and that 3 is not true (numerous measures of "declarer advantage" over double dummy both before and after the opening lead).

 

There are some minor quibbles with the book, in that the bidding of the authors differs from what I'd expect in some common auctions. For example they suggest that after 1M-1NT (where 1NT is non-forcing or semi-forcing) that opener will pass with most minimum 5M-4m hands, whereas in my experience most players will bid on these hands. They also assume most players will stayman with (43)33 type hands whereas my experience is the opposite (although they do give evidence that this does not make a huge amount of difference). Of course some partnership style in the auctions is unavoidable.

[jallerton]

I don't think you have to disclose how you decide which suit to lead, that's just bridge judgement.

 

LAW 40 - PARTNERSHIP UNDERSTANDINGS

 

A. Players’ Systemic Agreements

 

1. (a) Partnership understandings as to the methods adopted by a partnership may be reached explicitly in discussion or implicitly through mutual experience or awareness of the players.

 

(b) Each partnership has a duty to make available its partnership understandings to opponents before commencing play against them. The Regulating Authority specifies the manner in which this shall be done.

 

LAW 20F2. After the final pass and throughout the play period, either defender at his own turn to play may request an explanation of the opposing auction. At his turn to play from his hand or from dummy declarer may request an explanation of a defender’s call or card play understandings. Explanations should be given on a like basis to 1 and by the partner of the player whose action is explained.

 

If, like sfi, you have discussed your leading style with partner than you have an explicit partnership understanding. If you have played with someone for a while and notice what they tend to lead in certain situations then you have an implicit partnership understanding. Laws 40A1b and Law 20F2 imply that these understandings should be disclosed to the opponents.

 

If you know that your partner has an aggressive style of overcalls, you would disclose that fact to the opponents, would you not? If you know that your partner has an aggressive style of opening leads, why is that any different?

[barmar]

If, like sfi, you have discussed your leading style with partner than you have an explicit partnership understanding. If you have played with someone for a while and notice what they tend to lead in certain situations then you have an implicit partnership understanding. Laws 40A1b and Law 20F2 imply that these understandings should be disclosed to the opponents.

 

If you know that your partner has an aggressive style of overcalls, you would disclose that fact to the opponents, would you not? If you know that your partner has an aggressive style of opening leads, why is that any different?

 

So what kind of disclosure would you expect? "He's less likely to have led away from an honor than most other players"? That's probably about as specific as you can get about something like this.

[Cascade]

Whatever information you have. The example you give should be routine but is seldom disclosed.

 

I think it is bizarre that some people think they can play without disclosing their partnership understandings including implicit ones and partnership experience.

[FM75]

Having now read these books, I think they are in fact very good.

 

The authors have several ways to deal with the objections to double dummy:

 

1. They run sims to determine the frequency of the common "double dummy" positions people complain about where the lead solves a guess for declarer. All indications are that these positions are pretty infrequent and do not greatly change the results.

 

2. They attempt to infer logical reasons for the leads that succeed. For example, they observe that if the auction goes 1NT-3NT and I have a five-card minor, partner is very likely to be extremely short in that minor. This justifies the poor showing of the "lead from length" in this situation (leading from two or three small in a major is often better).

 

3. They compute the chance of partner having specific cards, opposite my lead from a given hand and a given auction. When opponents have most of the strength and most of the outstanding cards in a particular suit, your chance of hitting partner with the "magic" holding is really quite poor.

 

In general I find the objections to double dummy simulation unconvincing. The sims have a lot of data on their side. The objections have only anecdotal evidence, with no serious attempts at producing data.

For the most part, I agree. But a data scientist would strongly object to their publication.

1) They do not supply their data for independent review.

2) Their experiments are not "repeatable" (exactly) - can't reproduce the exact deals that they used.

3) Their experiments are not "repeatable" (even approximately), because they do not specify the constraints imposed on the deals.

4) They do not compare their results properly against a "null hypothesis". Was it better than the alternative - with respect to both correct predictions as well as false positives and negatives? By how much?

I laud the approach. I have criticized elsewhere the poor proof-reading - and obviously the errors missed in the second publication.

 

Kudo's for a scientific approach to the problems.

[Mbodell]

For the most part, I agree. But a data scientist would strongly object to their publication.

1) They do not supply their data for independent review.

2) Their experiments are not "repeatable" (exactly) - can't reproduce the exact deals that they used.

3) Their experiments are not "repeatable" (even approximately), because they do not specify the constraints imposed on the deals.

4) They do not compare their results properly against a "null hypothesis". Was it better than the alternative - with respect to both correct predictions as well as false positives and negatives? By how much?

I laud the approach. I have criticized elsewhere the poor proof-reading - and obviously the errors missed in the second publication.

 

Kudo's for a scientific approach to the problems.

 

How often does anyone manage to do all of that? I strongly agree that, at the very least, sharing code and underlying assumptions about auctions and holdings is very important. I think we (the computer literate/simulation literate bridge players) could very easily do loose peer review of trying to recreate some of their results to spot check do we get the same results as them, and if not, why not. There might be value there both in confirming their results and also seeing how differing assumptions (like no stayman with 4333) might change (or not change) the overall results.

[awm]

For the most part, I agree. But a data scientist would strongly object to their publication.

1) They do not supply their data for independent review.

2) Their experiments are not "repeatable" (exactly) - can't reproduce the exact deals that they used.

3) Their experiments are not "repeatable" (even approximately), because they do not specify the constraints imposed on the deals.

4) They do not compare their results properly against a "null hypothesis". Was it better than the alternative - with respect to both correct predictions as well as false positives and negatives? By how much?

I laud the approach. I have criticized elsewhere the poor proof-reading - and obviously the errors missed in the second publication.

 

Kudo's for a scientific approach to the problems.

 

1. There is no set of established journals or conferences on bridge theory. We, the bridge community, are the independent review.

2. Their experiments are repeatable; running double dummy sims is easy to do on your own. This is often the case with processes which are somewhat random -- you won't get the exact same result, but the long-term trends should be the same. Further, I don't think an exhaustive list of their coin flips (deals) is particularly useful in examining an analysis of a stochastic process, nor do I find that such listings are typically provided in academic papers.

3. They do specify the constraints on the deals in the books, at least in most cases.

4. I am not sure what "alternative" you want; it is not like opening leads are an exact science or follow established rules. At various points they do state null hypothesis (lead 4th from longest and strongest, lead top from three touching honors but low from two touching honors) and show that these are incorrect.

[whereagles]

Well, I'm not even sure talking about "null" or "alternative" hypothesis makes any sense for the leads. (In the classical, statistical sense of the term.)

 

It would make some sense for evaluating reliability of DD analysis:

 

H0: "DD play yields the same average amount of tricks of single dummy expert play." versus

H1: "The average amount of tricks is different DD vs SD."

[the hog]

If, like sfi, you have discussed your leading style with partner than you have an explicit partnership understanding. If you have played with someone for a while and notice what they tend to lead in certain situations then you have an implicit partnership understanding. Laws 40A1b and Law 20F2 imply that these understandings should be disclosed to the opponents.

 

If you know that your partner has an aggressive style of overcalls, you would disclose that fact to the opponents, would you not? If you know that your partner has an aggressive style of opening leads, why is that any different?

 

 

There are times when a truly idiotic post is made in these fora and this is one of those times. You open 1c and my pd overcalls 1s say on aqxxx and out. You expect me to alert for this? What a joke, the overcall is just bridge to me.I don't know whether these posts are made in some misguided way to show how ethical one pretends to be or whether they are just made in ignorance, but they are worthy of ignoring just the same.

[helene_t]

You open 1c and my pd overcalls 1s say on aqxxx and out. You expect me to alert for this?

Was anybody talking about alerting? I thought it was about disclosure in general, not necessarily alerting. Even if light overcalls are not alertable under your local regulations, I suppose you will tell your opps if they ask about it. Some CC templates have room for overcall style btw.

[the hog]

"Disclose that fact to the opponents" looks like alerting to me. Perhaps some players even want to alert the colour of their knickers?

[blackshoe]

"Disclose that fact to the opponents" looks like alerting to me.

Perhaps you need glasses.

[the hog]

Perhaps you need glasses.

 

 

Perhaps you need a brain? Certainly some shoe polish is required.

[barmar]

Whether an agreement is alertable is up to the RA. ACBL's Alert Procedures says; "Treatments that show unusual strength or shape should be Alerted." So the only question is whether a simple overcall with AQxxx and out is considered unusual.

[blackshoe]

Perhaps you need a brain? Certainly some shoe polish is required.

Well played, oh master of the Flame.

[gordontd]

"Disclose that fact to the opponents" looks like alerting to me.

My opponents ask about our overcall style and I tell them it's very sound at the two level. That's disclosure but not alerting.

[the hog]

My opponents ask about our overcall style and I tell them it's very sound at the two level. That's disclosure but not alerting.

 

Yes, I totally agree with this and if they ask I am more than happy to explain, Gordon, but re read JAllerton's post and you will see why I am making this point.

[gordontd]

Yes, I totally agree with this and if they ask I am more than happy to explain, Gordon, but re read JAllerton's post and you will see why I am making this point.

I don't see it like that Ron. I think Jeffrey is making the point (correctly in my view) that quite a lot of players are less likely to fully disclose their understandings about lead styles than they would be about their bidding styles.

[GreenMan]

The posts demanding disclosure said nothing about "if asked." Looking at the posts they were replying to, I can come to no conclusion except that they want "disclosure" to come unasked.

 

Something like "We don't always lead 4th Best from our Longest and Strongest against notrump"?

 

Or "We lead our suit unless we think we should try to hit partner's suit, or we decide a passive lead is called for."

 

If this sort of thing requires pre-alerting then the world has gone mad.

[the hog]

The posts demanding disclosure said nothing about "if asked." Looking at the posts they were replying to, I can come to no conclusion except that they want "disclosure" to come unasked.

 

Something like "We don't always lead 4th Best from our Longest and Strongest against notrump"?

 

Or "We lead our suit unless we think we should try to hit partner's suit, or we decide a passive lead is called for."

 

If this sort of thing requires pre-alerting then the world has gone mad.

 

Thank you. That is what I was saying.

[gordontd]

If this sort of thing requires pre-alerting then the world has gone mad.

We don't have pre-alerting here (where jallerton is posting from), or rather it takes the form of properly filling out the convention card and my guess is that is what he is asking for, as well as full explanations when asked.