# In bridge, does it make sense to “tighten” or 'loosen" up on bidding depending on vulnerability?

For instance, the minimum standard seems to be about 12 points to open with a five card suit, or 13 points with a four card minor. That makes sense with equal vulnerability (both vulnerable or both not).

Suppose you're vulnerable and they're not. Are there players that would pass 12-13 point hands, needing 13-14 points (depending on suit length), because of the greater penalties for going down.

Conversely, at favorable vulnerability, (they are, you're) not, would you shade your opening requirements down to about 11 points to try to catch up?

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Yes, totally it does.

Let's think about the game of Bridge clearly: what is vulnerability? Why is it part of the game? It can't just be that at some arbitrary times you score n points for pulling off a tricky contract, and at other times, for no particular reason, you score n*3 instead. That would seem a pretty random feature.

All vulnerability is, to my mind, is a way of stipulating that there are designated times during every game of Bridge where taking risks is penalized less heavily than at other times. A good player will know that it's worth pushing your luck to its limit while non-vulnerable, and playing it safe while vulnerable.

Bidding all your auctions "straight down the line" without any variation based on vulnerable or non-vulnerable status just doesn't make any sense to me. If you think that way, then the scoring becomes a matter of random factors that sometimes really benefit you and sometimes come down on you much harder than you deserve. Whereas the truth of the matter, at least as I see things, is that it's just another interesting tool to allow the skilled player to press advantages over a less skilled one. But to do that you have to be prepared to adapt your bidding strategy to the specific circumstances of every single hand.

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For opening suit bids no, emphatically not. The reason is simple mathematics in that when you open (in 1st or 2nd seat) you have no idea whether your side is looking at part score, game, or slam; and the appropriate aggressiveness towards each of these levels varies differently with vulnerability.

The relative worth of game to part-score goes up with vulnerability so it is appropriate to bid slightly more aggressively towards vulnerable games at IMP scoring. For example, it is appropriate to bid a non-vulnerable game with a 50% chance to make (ie requiring only a finesse) and appropriate to bid a vulnerable game with a 35% chance to make (requiring a finesse and a 3-2 break).

However the relative worth of slam to game goes down when vulnerable, so one should be slightly more cautious bidding vulnerable slams at IMPS. It is now appropriate to bid a non-vulnerable small slam with a 50% chance to make but only appropriate to bid a vulnerable small slam with a 65% chance to make (roughly requiring only a 3-2 break).

Empirically, these percentage differences are often estimated as representing about a 1 or 1.5 point difference in partnership combined strength, when better information is not available.

Third seat openings however can probably discount the possibility of slam when holding minimum values, so here the logic is that one should open slightly more aggressively, not less, when vulnerable, because of the increased relative value of game.

This is all nearly the complete opposite f your suggestion. Only when making a competitive part-score decision or a pre-emptive opening does the logic of the question hold true.

Therefore, until you know which levels your partnership is aiming for, it is inappropriate to adjust your bidding. This is done by having the inviter, only, make the adjustment and only with the inviting bid. Then the partnership can rely on all other calls being standard, allowing more consistent decisions to be made by the partnership.

As a final note, in regards Grand Slam bidding, Barry Crane (and the Four Aces before him) had a commandment to never bid grand slam in Swiss Teams (my emphasis):

The caution about not bidding grand slams in Swiss Teams made a lot of sense particularly if your opponents are not all that skillful as nothing is more demoralizing than to go down one at seven while the other team only reached game. In fact, I remember the original Four Aces of forty or more years ago had a rule that if you bid seven once and went down you would be forgiven but if you did it the second time you were off the team.

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The more I think about it, the more I believe that partnerships that are at unfavorable vulnerability ought to tighten up their bidding. But not necessarily the opening bidder, in the example I gave.

Someone needs to OPEN in order to get out information. They're not hugely vulnerable to doubles, because doubles of opening bids are usually for takeout. So you can maintain your opening standards when vulnerable.

It seems that it is the RESPONDER that needs to tighten up standards, e.g. respond at the one level with a full six points, at the two level with a full ten points, etc. Many otherwise makeable contracts are lost because dummy didn't have enough high cards to provide "transportation," and these are situations you want to avoid.

Also, one needs to be more careful about COMPETITIVE bids. Weak two bids need six cards, not five, and a good suit. Pre-emptive bids need two honors, not just seven cards in the suit. Raises of suits need honors to go along with spots. That's because THESE bids are most likely to be doubled. And if they are successful, the penalties (500 for down 2, 800 for down 3) will be large relative to the opposing game you are trying to "save."

A competitive bid that requires a high level of caution is a takeout double in the direct seat. If your partner has nothing, opener's partner will redouble, then (probably) double anything your team bids. At unfavorable vulnerability, you will need very good distribution (singleton or void in the opener's suit) for the likely penalty to be less than the game or slam the opponents can make.

Is it right to refrain from making a takeout double in borderline situations?

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When vulnerable, the game bonus goes up more than the penalties for undertricks. At IMPs, you should bid "40% games" -- that is, games that have a 40% chance of making vs going one down. Quick math: assume you make either 9 or 10 tricks in a major suit. If it's 9, and you bid game and your opponents stay out, it's -100 vs -140 for 6 imps lost. If it's 10, and you bid game and your opponents stay out, its +620 vs -170 for 10 imps. That means you should favor being in game if your odds of making are better than 6:10 = 37.5%. So it's not necessarily the case that you should be tighter when vuln. – ruds Feb 4 '13 at 6:16

Do people do this? and Is it sensible? are two different questions. There are systems that rely absolutely on this sort of thing: the Mini No Trump is opened on 10-12 points non-vulnerable and 12-14 vulnerable, and it's both legal and difficult to defeat.

But whether you should do it generally and without agreement is almost impossible to answer. If you'll pardon a platitude, you should open only if you think you have a better than even chance of ending up with a plus score. Whether your particular 12-point hand will give you that depends on its minor features (J109, doubletons, etc.), how active your partner and opponents are, and the comparative cardplaying skills of the four of you. There are certainly 11-point hands I would open without hesitation and 13-pointers I would pass, and vulnerability is one factor in that; but only one.

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Interesting response. What is your answer to this question? boardgames.stackexchange.com/questions/8308/… – Tom Au Feb 2 '13 at 17:22
@Tom: As ever, it depends on many things. But you should also consider that if you open a weak hand (or pass a 13-pointer) this time, your partner is less able to trust you next time. – TimLymington Feb 2 '13 at 17:37
I meant, suppose you AND partner have an agreement to open "light" at favorable vulnerability, and pass some 13 pointers when vulnerable vs. not. – Tom Au Feb 2 '13 at 17:39
@Tom: now I'm really confused. If your partnership agreement is to open borderline hands green but not red (perfectly normal though it should probably be declared at duplicate), then your other hand is a perfect example: is that really what you are asking? – TimLymington Feb 2 '13 at 17:45
If I understand your response, the answer would be yes. – Tom Au Feb 2 '13 at 18:03

In my understanding, vulnerability matters most in competitive bidding, especially when deciding whether to preempt or sacrifice, not strong openings. This page by bridge expert Richard Pavlicek, for instance, indicates that the strength of a preemptive bid should vary from 2-4 depending on whether the vulnerability is unfavorable, even, or favorable.

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