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Vulnerable and Non-vulnerable two questions

#1 User is offline   jfy18 

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  Posted 2004-August-19, 17:34

When playing duplicate bridge while vulnerable, there are bonuses to successfully bidding game (ie. 500 instead of 300) but also greater costs to being set.

Bearing this in mind, are there any reasons why one should be (either) more or less aggressive when bidding vulnerable, given that there are both extra costs and benefits for so doing?


I can see that if one is vulnerable and the opponents are not, one should expect opponents to be more likely to attempt to make a 'save' against one (because going down will cost them comparatively little, and they will be able to stop one getting a high game bonus). But nonetheless I suppose a similar (perhaps equivalent) question to the above is: should bidding be any different when both pairs are vulnerable, compared to bidding when both pairs are not?


JFY
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#2 User is offline   mikestar 

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Posted 2004-August-19, 17:46

In matchpoints, vulnerability makes no difference in constructive bidding. At IMPs, you should be more aggresive in bidding games--you are getting odds of 10-6 vulnerable on bidding game (assuming exact make or down 1, no double) vs 6-5 non-vulnerable. Slam odds are comparable at either vulnerability.

In competive bidding, you can afford to be more agressive at neither vulnerable than at both vulnerable. The two situations are equivalent when competing at the game level and above, but in a partscore battle, both vulnerable carries greater risk of -200 if you bid to high and greater chance of +200 is they do. This effect is more pronounced at matchpoints as 200 can be top or bottom on a partscore deal, but the gain or loss is more modest at IMPs.
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#3 User is offline   jtfanclub 

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Posted 2004-August-19, 20:02

jfy18, on Aug 19 2004, 06:34 PM, said:

When playing duplicate bridge while vulnerable, there are bonuses to successfully bidding game (ie. 500 instead of 300) but also greater costs to being set.

Bearing this in mind, are there any reasons why one should be (either) more or less aggressive when bidding vulnerable, given that there are both extra costs and benefits for so doing?


I can see that if one is vulnerable and the opponents are not, one should expect opponents to be more likely to attempt to make a 'save' against one (because going down will cost them comparatively little, and they will be able to stop one getting a high game bonus).  But nonetheless I suppose a similar (perhaps equivalent) question to the above is: should bidding be any different when both pairs are vulnerable, compared to bidding when both pairs are not?


JFY

When you're not vulnerable and they are, the light is green...bid and bid more.
When neither side is vulnerable, the light is white...bid normally.
When both are vulnerable, the light is yellow...bid normally.
When you're vulnerable and they're not, the light is red...stop early, unless you have game.

That's how I was always taught. :)
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#4 User is offline   EarlPurple 

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Posted 2004-August-20, 11:20

If you are playing IMPs (team-game) your opps bid a vulnerable game against you which your team-mates don't manage to reach (sure you wouldn't miss a game!), you score -620 while they get only +170 and you've lose 10 imps.

But on the next hand when you bid the non-vulnerable game you score +420 and the other table that misses it so you get just 6 imps.

Now what happens if you push to a game that doesn't make? Assuming the opps don't double and you go just 1 off, you lose -100 and -140 as the other table stops in the part-score. That's 6 imps non-vulnerable. So the odds are about 10 to 6 vulnerable, i.e. 37.5% for the game to make. But in reality the opps do sometimes double (and you might go 2 off) and so your odds should be a bit better than that.

If non-vulnerable you lose -50 and -140 which is just 5 imps. So it's only 6-5 in favour of bidding the game. Given the possibility that they might double, you can treat that as fairly even odds.
You can't keep a good man down
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#5 User is offline   MickyB 

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Posted 2004-August-20, 13:34

EarlPurple, on Aug 20 2004, 06:20 PM, said:

So the odds are about 10 to 6 vulnerable, i.e. 37.5% for the game to make. But in reality the opps do sometimes double (and you might go 2 off) and so your odds should be a bit better than that.

Only if the choice is between 1NT and 3NT, or 2M and 4M. More commonly it is a choice between game or one less than game, which actually reduces the required odds to bid game, as if you bid on when you were already going off then it will only cost an imp or two (assuming the opps don't double).
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