This is a topic I've been thinking about writing on for some time now. EBTAS is essentially a group of sub-principles of bridge bidding:
- the principle of no undos;
- the principle of telling your story once only;
- the principle of substantive discretionary bids;
- the principle of fast arrival;
- the curious principle of the dog in the night-time.
Each call you make, be it a suit you bid, notrump, pass, double or redouble tells partner something about your hand that he didn't already know. Unless you're deliberately psyching, every bid you make should continue to refine the description of your hand. This is especially true of non-forced bids, for a forced bid may have to be made on non-ideal cards.
Let's examine the sub-principles one by one. That there are no undos is self-evident. It's incontrovertible. To take an extreme example, partner open 1♣ and you hold ♠KQJ5
♥5432
♦Q86 ♣54. You decide you like spades better than hearts so you bid 1♠. Partner now rebids 1NT. If you now bid 2
♥, your partner will now "know" that you are 5-4 or 5-5 (or more extreme still) in the major suits. No matter how you bid from here on, partner will never believe you are 4-4.
"Don't tell your story twice" is what every novice bridge player is told again and again. Let's say you hold ♠KQJ8752
♥5
♦Q6 ♣542, non-vulnerable versus not. You deal and open 3♠ and LHO bids 4
♥, partner passes and RHO passes too. You now bid 4♠. You've told the same story twice. You had a reasonable 3♠ call that pretty much described your hand. Partner decided not to act over 4
♥. You have no reason at all to bid again. Partner might have ♠4
♥QT85
♦A875 ♣K976. Between you, you have a likely one spade, two or even three hearts, one or two diamonds and possibly a club on defense. On offense, you have 6 spades and 1 diamond. Enough said.
The principle of substantive discretionary bids ("the principle of stuff", for short) is my own rule and I admit that I'm still looking for a pithy name for it. I've never seen it espoused
per se by any expert, but nevertheless, I think it probably is considered to be plain common sense. It basically says that if you make a non-forced (discretionary) bid in a suit, then you show some values in that suit. The kind of values you'd like to be led to if partner gets on lead. So, any time you make a discretionary bid (where pass is a logical alternative) you show "stuff". Let's say that your hand is ♠Q8752
♥5
♦A6 ♣AQJ42, not-vulnerable vs. vulnerable. Partner deals and passes, your RHO opens 1
♦ and you bid 1♠. LHO makes a negative double and partner passes. RHO now bids 2
♥. Do you bid 3♣? It's reasonable, maybe not automatic but generally OK. If partner does happen to get on lead, you'll welcome a club lead. But suppose your hand is instead ♠AQJ42
♥5
♦A6 ♣Q8752. The auction goes the same way. Should you bid 3♣ now? Some might but I wouldn't. You barely have any "stuff" in your club suit. Instead, with this hand, I might bid 2♠ at my first opportunity (although admittedly it's heavy for a jump even opposite a pass).
Occasionally, you will be dealt a very good hand except that your long suit is rather weak. You simply have too many points to pass. So an overcall is not truly discretionary because you feel you have to do something. Partner will expect a better suit, but the overall strength of the hand should help to ameliorate any issue arising.
Let's not get confused with normal constructive bidding here. Suppose the auction went 1♠ pass 1NT pass. Everyone on this planet would rebid 2♣, regardless of which of the two hands they hold. They would simply be "patterning out". Their rebid is not discretionary, especially so if the 1NT was forcing (regardless, it's incumbent upon opener to rebid a suit with such an unbalanced hand). No inference could be made by partner that you have better cards in one black suit versus the other.
The principle of fast arrival is too well known to require any long-winded elaboration from me, but let's just put it in this way: if you have two ways of getting to a particular contract all on your own, the indirect route shows the stronger hand. Let's take a simple example. You are dealt ♠AQJ742
♥5
♦K6 ♣Q852 and partner opens 1
♦. You bid 1♠. Partner now bids 1NT showing 12-14 hcp. You know you want to be in 4♠, but you have two ways to get there: bid 4♠ immediately or go through new minor forcing. The principle of fast arrival says that if you jump straight to 4♠, you don't expect partner to bid again – he's limited his hand quite narrowly. But if you bid 2♣ and then over the likely 2
♦, 2
♥, 2NT or 3♣ rebid you
now bid 4♠, you are saying that you would be interested in slam if partner has good working cards and/or a spade fit. Perhaps you would need to have at least ♠AQJ742
♥5
♦K6 ♣A852 to use this route.
Finally, we have the curiously named "curious principle of the dog in the night-time" (dog principle for short). I admit to naming this one too. The allusion of course is to Sir Arthur Conan-Doyle's short story "Silver Blaze". Inspector Gregory asks "Is there any other point to which you would wish to draw my attention?" Holmes: "To the curious incident of the dog in the night-time." Gregory: "The dog did nothing in the night-time." Holmes: "That was the curious incident."
Let's say that your partner opens 1
♥ and your right-hand opponent bids 1♠. You cue-bid 2♠, which is of course forcing to 3
♥. LHO doubles. Partner passes. That's to say he does nothing. But nothing is something in this context. Partner had the choice of calling 4
♥, 3
♥, 2NT, 3NT, redouble, or three or four of some minor suit. But he did none of these things. His pass is forcing on you to do something (you've already told him that we want to play at least 3
♥), but he is leaving the door open for you to do something below the level of 3
♥ if you wish, such as to make a game try. Most probably, partner has no extra distribution but most probably he has extra high-card points. With neither of these, he would simply bid 3
♥ (fast arrival) effectively closing the door to any game tries you might otherwise have made. Of course, different partnerships might have different agreements, but I think this would be the standard agreement without any discussion.
Now, for an example of the principle in action:
Every bid tells a story. Let's say that you pick up the following hand: ♠AQJ9
♥754
♦KJ6 ♣K92. What you have is a nice balanced 14 count. You open 1♣ and partner bids 1
♦. RHO now bids 1
♥. You have a bit of a problem. Should you bid 1♠ (and perhaps suggest at least four clubs), or should you make a support double? Or fib a bit and bid 1NT? Or should you pass? I think the latter is too wimpy. And I think 1NT is too dishonest. Let's say that you bid 1♠, and later you show support for diamonds. You are showing better than a minimum hand (fast arrival). With, say, ♠KQJ9
♥754
♦KJ6 ♣Q92 (in my opinion, not really an opening hand at all playing standard American or 2/1), you would reluctantly perhaps have to make the support double and potentially miss your spade fit (although if partner's hand is good he will check back somehow).
Now, suppose that over our 1♠, partner bids 1NT and RHO bids 2
♦. Do you double now? If you have the 14 point hand above, you have already described your hand reasonably accurately (partner may expect a fourth club but will realize that you might not have had a perfect 1NT rebid after the heart overcall). If you double here, you're telling partner that you have a balanced hand with defense in both red suits (you won't be surprised if LHO takes a preference to hearts so you'll want to have some defense there too).
And considerable extra values, given that you would have opened with 1NT if you had a balanced 15-17. Perhaps this hand: ♠AQJ9
♥KJ4
♦KJ6 ♣K92.
Thus, if the auction goes as described, partner will really expect you to have a rather good defensive hand. If he should chance to double 2
♥ with ♠T2
♥AT2
♦QT84 ♣T765 (maybe he shouldn't!), he's going to be awfully disappointed if you show up with ♠KQJ9
♥754
♦KJ6 ♣Q92.
Another example comes from a common situation: ♠KQT92
♥74
♦KJ6 ♣K92. You open 1♠, LHO bids 2
♥, partner passes, RHO comes in with 2♠. Do you double? Of course not! Partner already knows you have five spades (assuming you're playing 5-card majors) and is planning to lead them whatever you do. On this occasion, it's true that you have nice ones. But double here shows
extras. Possibly just a sixth spade, but generally speaking you show more than a minimum opening.
So, take care with those frivolous bids or doubles that "can't possibly come to any harm". You might get away with it when the next player bids something, but partner may take some later action in the fond illusion that you actually had something for your earlier action.