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Knowing how far to compete/sacrifice

#1 User is offline   thepossum 

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Posted 2022-April-05, 02:42

Hi all

This hand came up recently in an MP Bot tourney (correction IMPS)
I considered competing further but ended up being part of the crowd who tried defending 4 or 5 spades (some unfortunately 5Sx)




Without the interference I would have been considering possible slam (not really)
Also white versus red but something stopped me (and others) competing too far - maybe the hearts

You can afford 3 down doubled can't you?

P
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#2 User is offline   LBengtsson 

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Posted 2022-April-05, 04:48

White/red I always bid one more. The K is, I guess, dead, West more like to have the A. Also, looks like they have a 9 card fit with suit breaking 2-2. I would like to bid 5 here to suggest a lead as opposed to 5 direct, but that is up to partnership agreement. I do not wish partner to think that is a slam encouragement.
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#3 User is online   DavidKok 

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Posted 2022-April-05, 05:10

I'd bid 5, which shows a shapely hand with side diamonds. Partner may raise to 6 or compete over 5 with a suitable hand. Of course we won't be making any slams, but if partner has diamond length we're not setting 5 and I'd rather sacrifice at these colours. Given the forum I'm also a little bit scared that the 2 bid might be the system bid on a different set of hands than what I'm used to, possibly by sufficiently much to make 5 anti-percentage. Oh well.
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#4 User is online   helene_t 

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Posted 2022-April-05, 07:28

Larry Cohen's "To bid or not to bid" covers this nicely.

Here you think that your side has 8 hearts and opps have 10 spades, so 18 tricks in total if the LAW can be trusted. This means that if opps can make exactly 10 tricks, your side can make 8 tricks which would make a sacrifice lucrative, but if they can make 11 your side can make only 7 hich would be too expensive - you are allowed to go 3 down at this vulnerability. And, of course, if they can make only 8 or 9 tricks, 5 would be a phantom sac.

If opps can make 7 tricks, your side can make 11. Then double is better than bidding, but you might not be considering doubling. Passing carries the risk of getting +300 when you could make +450, but thats a relatively small loss at IMPs considering all the other disasters that can happen on this board. Of course, against the alternative of collecting 800, 300 would be a huge lost opportunity.

Since 8, 9 or 11 is more likely than exactly 10, you should probably probably not bid 5, but there may be adjustments that could favour bidding:
- Your side may have a double fit - if partner also has diamond length, your diamonds would be useful only when declaring, not when defening
- there could be more than 18 total trumps
- Your singleton clubs is probably more useful for declaring than for defending. Consider that even if p has Axx of clubs and may be able to give you one or two ruffs, you don't always find the optimal defence

On the other hand, there could also be negative adjustments:
- Your spade holding is almost certainly useless when declaring, it may be a bit more useful when defending although it's not very likely
- Your trumps are poor, this makes it likely that one of the opps have a hearts holding that is more useful when they defend than when they declare

Sometimes bidding 5 can be good tactic because it may induce opps to bid too high.

It is also important to think of what double would mean, and if partner may do something if you pass. Here, partner will certainly pass no matter what you do (unless you bid something fancy like 4NT or 5).

If you consider bidding 5, bid 5 instead in case partner will have to lead against 5.
The world would be such a happy place, if only everyone played Acol :) --- TramTicket
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#5 User is online   smerriman 

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Posted 2022-April-05, 15:24

With a human, I agree with others about 5 - helps partner know what to bid and/or lead if the opponents compete to 5. I don't want to defend 4 when my Kx is wasted and diamond tricks may be non-existent if one opponent is short.

But wouldn't dream of that with GIB, since it shows 22 total points and it'll probably bid 6 on hands where even game isn't making. You might be able to get away with 5 if that gets passed out - if the opponents bid 5, you might be in trouble since GIB won't make good decisions over that (AKA it will double regardless of what it holds).
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#6 User is offline   thepossum 

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Posted 2022-April-05, 21:27

View PostLBengtsson, on 2022-April-05, 04:48, said:

White/red I always bid one more. The K is, I guess, dead, West more like to have the A. Also, looks like they have a 9 card fit with suit breaking 2-2. I would like to bid 5 here to suggest a lead as opposed to 5 direct, but that is up to partnership agreement. I do not wish partner to think that is a slam encouragement.


Thanks, yes I wish I had showed my diamonds. That is how people found their way to competing to 6
It was terrible leaving them unmentioned. I almost opened diamonds

Always disappointed when I consider competing much higher and chicken out
Someone even scored well redoubled
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#7 User is offline   thepossum 

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Posted 2022-April-05, 21:41

Sorry, this was the full hand. Those who competed to 6 scored well - but don't try high level takeouts. Dangerous
If you bid 5D partner ended up in 6H


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#8 User is offline   thepossum 

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Posted 2022-April-05, 21:44

View PostDavidKok, on 2022-April-05, 05:10, said:

I'd bid 5, which shows a shapely hand with side diamonds. Partner may raise to 6 or compete over 5 with a suitable hand. Of course we won't be making any slams, but if partner has diamond length we're not setting 5 and I'd rather sacrifice at these colours. Given the forum I'm also a little bit scared that the 2 bid might be the system bid on a different set of hands than what I'm used to, possibly by sufficiently much to make 5 anti-percentage. Oh well.


the 2H is simply the GiB 2/1 system bid. Described as a free limit, as opposed to a regular limit - after interference??
Sorry free major raise - not limit?
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#9 User is online   DavidKok 

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Posted 2022-April-06, 00:16

I understand the description, and I would never bid it on that North hand. I think that proves the point.
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#10 User is offline   P_Marlowe 

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Posted 2022-April-06, 03:19

View Postthepossum, on 2022-April-05, 21:44, said:

the 2H is simply the GiB 2/1 system bid. Described as a free limit, as opposed to a regular limit - after interference??
Sorry free major raise - not limit?

2H is wrong, .., ... the GIB system bid is something like 2S.
However you count total points, you have more than 6-10.
With kind regards
Uwe Gebhardt (P_Marlowe)
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#11 User is offline   akwoo 

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Posted 2022-April-06, 14:18

Frankly, GiB is so terrible in these situations even compared to a moderately competent human that I wouldn't worry about it.

Playing opposite GiB, this is purely a guessing game.
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#12 User is offline   mikeh 

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Posted 2022-April-07, 18:21

Indeed, my own view is that there should be a separate forum for GIB ‘bridge’ since GIB bidding has no discernible resemblance to even moderately competent human bidding.

Advice about a bidding sequence with a human is pretty easy to provide. Advice about the same sequence with a robot on BBO? I’m sure there are good players who have developed some understanding of the algorithms used by GIB such that they can tell you what to do, but their reasoning won’t resemble ‘bridge’. They won’t tell you why their advice makes sense other than as a p,or to ‘game’ the robot.
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari
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#13 User is offline   TylerE 

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Posted 2022-June-08, 17:30

I really dislike saccing at the 5 level holding 2 likely defensive tricks.

This is the WORST sort of hand to sac on...too much defense, not enough offense. Wouldn't surprise me if everyone is -1.

A hand like, say !S x !h JTxxxx !D AQxxx !C x and now we're in the ballpark.
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#14 User is offline   Lovera 

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Posted 2022-September-11, 06:06

View PostP_Marlowe, on 2022-April-06, 03:19, said:

2H is wrong, .., ... the GIB system bid is something like 2S.
However you count total points, you have more than 6-10.


Yes, "Total Points" are used for the line that open the bidding whilest it's better to use "Points Schomoints" by Martin Bergen when are opponent. Anyhow i agree for 2 and suggest to see what means for GIB that one if it is possible (N has 8 HCP+2 points for 5th. card at and + 3 points for shortness for a total of 13 p.)(Lovera)
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#15 User is offline   Douglas43 

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Posted 2022-September-12, 09:50

Most people would bid 4 on the North hand. Why GiB selected 2 goodness knows.
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#16 User is offline   Gilithin 

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Posted 2022-September-12, 10:25

View Postmikeh, on 2022-April-07, 18:21, said:

Indeed, my own view is that there should be a separate forum for GIB ‘bridge’ since GIB bidding has no discernible resemblance to even moderately competent human bidding.

There is a separate forum for GIB but sometimes posters forget to use it. I agree wholeheartedly with the chorus saying that no competent human would bid 2 with that hand.
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#17 User is offline   thepossum 

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Posted 2022-September-12, 18:16

I did acknowledge Mike's point I think but sometimes I think maybe the issue is a broader beginner question beyond the competence of my partner

Just checking that it is not my bid under question
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#18 User is offline   Gilithin 

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Posted 2022-September-12, 19:06

View Postthepossum, on 2022-September-12, 18:16, said:

Just checking that it is not my bid under question

North has at least 3 calls - 4, 3 and 2 - that I would put ahead of 2 in my Nigel-style bid ratings. Any of these would give you a much better chance of getting this right.
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#19 User is offline   michel444 

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Posted 2022-September-19, 14:07

View PostP_Marlowe, on 2022-April-06, 03:19, said:

2H is wrong, .., ... the GIB system bid is something like 2S.
However you count total points, you have more than 6-10.

the story is realy funny a robot make 1 spade overcall with 6 Spade headed by a JACK
the other robot bid 2 H... and the third bid 4 spade
the robot are no the problem but the Programmer who do a lousy job on writing program
.E-W the ROBOT have 6 Spade! or 6 Club !
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#20 User is offline   Gilithin 

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Posted 2022-September-19, 14:32

View Postmichel444, on 2022-September-19, 14:07, said:

the story is realy funny a robot make 1 spade overcall with 6 Spade headed by a JACK

Quite so, I much prefer 2 opposite a passed hand. Missing a 19hcp slam in a jammed auction is completely normal.
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