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match point strategy

#1 User is offline   luke warm 

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Posted 2005-April-21, 18:52

here's an example from rubens' great book, the secrets of winning bridge .... i'll post the hand, i look forward to the conversation...

Q6543
AK
AK
6432

AT987
543
542
AK

you are south, vulnerable, and are in 6... the lead is the J... as you can see, the contract is cold... however, this is matchpoints... there are 19 other tables, 9 other n/s pairs

how do you play the hand, and why do you select that particular line? have fun :)
"Paul Krugman is a stupid person's idea of what a smart person sounds like." Newt Gingrich (paraphrased)
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#2 Guest_Jlall_*

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Posted 2005-April-21, 22:20

I wouldn't safety play unless the field was so weak that I thought I had a very near top score by just getting to 6S. I would almost always play a spade to the ace.
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#3 User is offline   awm 

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Posted 2005-April-22, 01:13

After winning the lead in dummy I'll lead a spade towards hand. If RHO follows small, I will take the safety play of putting in the 9.

There are only two particularly interesting positions: stiff king on my left and KJx on my right. And other situation and this play is unlikely to matter. These two positions are very close to equally likely. Playing the 9, I stand to win a full matchpoint from each table in slam that plays the ace when I am right, and will lose a full matchpoint to each table in slam that plays the ace when I am wrong. Playing the A, I stand to win a full matchpoint from each table in slam that plays the nine when I am right, and will lose a full matchpoint to EVERY table, in slam or no, when I am wrong.

Seems to me that if even one table in the room fails to bid the slam, my expectation will be best by taking the safety play.
Adam W. Meyerson
a.k.a. Appeal Without Merit
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#4 User is offline   MickyB 

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Posted 2005-April-22, 01:36

A priori, KJx on right will occur 11%, K singleton on left 13%.

If I play the ace, then I gain one MP (half a US MP) from the other pairs in slam if I am right.

If I guess to play the ten, then I gain one MP from the other pairs in 6 and *two* MP (one US MP) from the other pairs in 4.

This analysis suggests that the breakeven point is when one-twelfth of the other tables don't bid slam, which in most fields is enough evidence to take the safety play IMO.

[snip a load of stuff based on 6NT making :) ]

BTW Luke, is the field 10 tables or 20? Not that it should make any difference to our decision :unsure:

This post has been edited by MickyB: 2005-April-22, 03:21

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#5 User is offline   helene_t 

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Posted 2005-April-22, 02:15

Just another old trick: Play a low spade towards the queen. Maybe West thinks his p has the ace sec and ducks from KJ or K2.

Btw, how can 6NT be made? I don't see it.
The world would be such a happy place, if only everyone played Acol :) --- TramTicket
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#6 User is online   P_Marlowe 

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Posted 2005-April-22, 02:40

Play it safe, i.e. spade to the Ten.

I can speak only for myself, but at least I
do not play in a fields, were every table
will reach 6S every time.

Even in top level events, it may happen
that they miss 6S.
And at least some of the people who did reach
6S will play it safe.

If you really believe, that every table is in
6S, then play low to the ace, losing only in
case RHO holds KJx.

With kind regards
Marlowe
With kind regards
Uwe Gebhardt (P_Marlowe)
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#7 User is offline   MickyB 

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Posted 2005-April-22, 03:19

Erm...you have a point Helene, slight lack of tricks lol
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#8 User is offline   Gerben42 

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Posted 2005-April-22, 03:28

Good analysis. Going down is just too costly for this slight edge.
Two wrongs don't make a right, but three lefts do!
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#9 User is offline   FrancesHinden 

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Posted 2005-April-22, 03:47

I'm sure there exist fields (World Pairs final?) where everybody will be in 6S, but I haven't found one yet. I would take the safety play.
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#10 User is offline   kgr 

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Posted 2005-April-22, 03:58

I would cross to my hand in and play 10, planning to put the Q in dummy. Combine safety play with possibility that LHO misdefends with Kx.
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#11 User is offline   pclayton 

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Posted 2005-April-22, 09:01

Just bang down the A. Still pick up KJx on left and stiff Kings.

I'm 2:1 favorite over those that take the safety play for more tricks. Hearts might be 7-1 as well, which skews it a little more for the A.

Adam's play is probably better though.
"Phil" on BBO
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#12 User is offline   MickyB 

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Posted 2005-April-22, 09:51

pclayton, on Apr 22 2005, 04:01 PM, said:

I'm 2:1 favorite over those that take the safety play for more tricks.

No you're not...small to the ten picks up stiff king with RHO (well, as long as you don't still put the ten on the trick :) )
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#13 User is offline   Rebound 

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Posted 2005-April-22, 10:17

Dumb question deleted.

This post has been edited by Rebound: 2005-April-22, 10:18

I'd rather have a bottle in front of me than a frontal lobotomy - but it might improve my bridge.
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#14 User is offline   Rebound 

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Posted 2005-April-22, 10:20

I'm pretty sure at the table I'm just going to play the A.
I'd rather have a bottle in front of me than a frontal lobotomy - but it might improve my bridge.
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#15 User is offline   luke warm 

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Posted 2005-April-22, 17:03

excellent discussion, very interesting, the reasoning used here by some very good players... this is what rubens has to say about it, and probably shows why i'm not an expert

first of all, he tries to decide what the normal contract would be, then what the alternative contracts might be... with this hand, even tho slam happens to be cold, he reasons that it isn't a particularly easy slam to reach... micky is right that the odds are roughly even (13:11), which means it's only correct to play for the overtrick if more than twice as many pairs bid 6s as stop in game (or bid 6nt or 7nt or 7s)... rubens thinks that is highly unlikely, and he's probably right that at *least* as many will be in 4s as in any slam

all declarers in 7nt are down, so making 6s beats them automatically (assuming the safety play)... those in 7s have to play the ace of spades, playing for a stiff king, since it's the only way to lose no spade trick... it either makes or it doesn't... so if the K is stiff, you lose to the 7s bidders and to all 6s bidders who bang the ace...

the 6nt bidders have only one chance for a good score, and that is to lead the Q (hoping for a stiff jack with west)... on any other distribution, they're gonna lose to some 7s bidders and all 6s bidders ... so hope for the stiff jack if you're in 6nt

this all boils down to rubens belief that if you take the safety play you will win much more often than you lose... he bases it on his belief that in very few (he says in probably none) tournaments will anything approaching twice as many people be in 6s as in 4s... so lead low from dummy to the 10 and take your cold slam (of course, if east shows out it's still cold... just go up with the ace and lead back)
"Paul Krugman is a stupid person's idea of what a smart person sounds like." Newt Gingrich (paraphrased)
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#16 User is offline   luke warm 

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Posted 2005-April-22, 17:26

oh by the way, awm's and micky's reasoning is right on... so if my post didn't make sense, read theirs
"Paul Krugman is a stupid person's idea of what a smart person sounds like." Newt Gingrich (paraphrased)
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#17 User is offline   HeartA 

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Posted 2005-April-22, 17:51

Gerben42, on Apr 22 2005, 04:28 AM, said:

Good analysis. Going down is just too costly for this slight edge.

I will play safe (low to 10) as well.
Senshu
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