Chances   


A bridge problem-corner conducted by Richard Cowan
rcowan@mail.usyd.edu.au 

for the Bulletin  of The Lindfield Bridge Club


The bridge problems in the Chances column involve an assessment of probabilities for competing strategies.  Brief solutions are reported in the Bulletin, while full solutions appear on this website. Columns 1-9 were run as a Club competition. From Column 10 onward, the competition format was dropped and the Chances column merely discussed bidding and card-play issues where probabilistic analysis is fruitful.

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Column 17.

North-South bid to 7NT with the cards shown in diagram (a), using an auction which marks South with a 3334 shape and 17-18 HCP (including one ace and two kings). West leads the J. South plays off winners to reach the 3-card ending shown in (b), noting that both opponents followed suit to each trick. He also noted that West played 10 and  9 on the second and third round of diamonds (as one would do if dealt J109, J109x or J109xx -- using the principle of playing what one is known to hold). He also noted that neither the Q nor J fell.

What is the chance, given the information to date, of making 7NT from situation (b) using the best line (which obviously starts by cashing the Q, pitching the 4 and observing both discards)

You'll have to consider all possible discards for the opponents. As an example, what is your best line and chance of success once (c) is reached if both discard a diamond on trick 11 and West plays x when you lead the 7?

a)  7NT

   North
AK42
AK105
82
AJ6

  South
J53
Q73
AKQ
KQ32

b)  end-game

   North
4
K10
-
-

  South
J
7
-
Q

c) trick 12

   North
-
K10
-
-
             
  South
J
7 (now led)
-
-

A solution is available; see the Column 17 download -- which has some interesting theory
about "vacancies", "free choice issues" and "game theory"


Column 16 (from the club's "Feb-March, 2006" Bulletin).

Deal (a) occurred during the 2005 Bermuda Bowl. The Australian Open team was playing Brazil. The contract at both tables was 7H.

In attempting to understand better the issues entailed in such a hand, I posed a somewhat simplified version, deal (b). My “generic” form of the deal has solid trumps (having no risk of over-ruff) and no lower honours nor high pips in the side-suits. So your resources are limited to the 9 trumps, the 5 outside high tricks and potential long tricks in the minor suits.

 Suppose, on deal (b), that West leads the 3 and East follows. What is the best line of play?

Thanks to Len Dixon for drawing my attention to the deal.

a)  actual

   North
AQ
AQ86
AK1087
J10

  South
3
KJ1073
96
AK732

b)  simplified

   North
A2
AJ97
AK652
74

  South
7
KQ1086
84
AK653

For the chances of success with deal (b), and some remarks on what actually happened
in the Brazil-Australia match with deal (a), see the Column 16 download.


Column 15 (from the club's "Oct-Nov, 2004" Bulletin).

What is the chance of making 7H by South on deal (a)? You have 11 high tricks and the potential to ruff two spades. My guess is that you will rate your chances highly on this "no-loser contract".

What about deal (b) played in 6H with the A missing? Or (c) and (d) which differ only from (a) and (b) in one way, the 9 appearing in dummy.

Deal (e) no longer has the Q; how does 6H rate? Finally, does that lovely 8 in deal (f) compensate for the fact that we have only 9 high tricks in 6H, with some hopes of a 10th via the J?

a)  7H

   North
K9
6532
A853
AK9

  South
A764
AKQJ10
4
Q43

b)  6H

   North
K9
6532
A853
AK9

  South
A764
KQJ109
4
Q43

c)  7H

   North
K9
9532
A853
AK9

  South
A764
AKQJ10
4
Q43

d)  6H

   North
K9
9532
A853
AK9

  South
A764
KQJ108
4
Q43

e)  6H

   North
K9
6532
A853
AK9

  South
A764
AKQJ10
4
743

f)  6H

   North
K9
8532
A853
AK9

  South
AJ74
KQJ109
4
743

For answers, see the Column 15 download. The column provides some theoretical insights into 5-4 fits.


Column 14 (from the club's "Jan-Feb, 2004" Bulletin).

After the auction 1D-1H <> 2NT-3NT, South received the  5 lead. The leading convention was "4th highest from length". East played the  K.

There appear to be two distinct lines of play. One of these, Line A, is the play of the diamond suit, hoping to derive 4 tricks from the suit. The other line, Line B, tackles the heart suit first – low toward KQ2  –  with  a  fall-back  on  the finesse against the Q should West have the A. This line relies on the clubs breaking 4-4 and West not having both the Q and A. In both lines, sensible management of the spades to provide entries to dummy, without blocking the suit, is achievable.

How should one play the hand?       Thanks to Les Varadi for providing  the deal.

   North
AQJ
9876
J86
874

  South
K932
KQ2
AKT5
AJ

 For the solution, see the Column 14 download.


Column 13 (from the club's "Nov-Dec, 2003" Bulletin).

You pick up a balanced hand of 16 HCP and plan to open a 15-17 1NT. Partner, however, opens before you, with 1NT.

I saw such a hand recently; the responder bid 6NT directly. Was it wise, do you think, for him to bypass the ace-asking convention?  What do you think the chances of the partnership missing two aces would be -- given responder's 16 HCP and the information that opener's range is 15-17?

 

 

For an answer which has some interesting tables about the
likely holdings of control cards when the partnership
has a given number of HCP, see the Column 13 download.


Column 12 (from the club's "Aug-Sept, 2003" Bulletin).

As  dealer  sitting South, in  a  tournament  with  IMPs scoring, you open 1S showing 5+ spades. LHO passes, partner bids 1NT (the usual 6-9 with at most 2 spades) and RHO passes. What do you bid? 2H or Pass? EW are vulnerable. Take a view before reading the analysis.

 
  South
AT542
J752
K42
A
 

For answers, see the Column 12 download.


Column 11 (from the club's "June-July, 2003" Bulletin).

All of the CHANCES columns to date have focussed on problems of card play. Yet considerations of the probabilities also arise in bidding; a recent hand from Thursday-night bridge at Lindfield illustrates this.

As South you must decide where to place the contract. Your partner has shown 25+ HCP, with no 5-card suit and no singleton. Upon enquiry you learn that he has 3 aces and 3 kings. Do you bid 7NT or subside in 6NT?

   North
AKJ9
KQ94
AJ
AKT

  South
QT6
AT2
Q2
QJ954

For answers, see the Column 11 pdf download.


Column 10 (from the club's "April-May, 2003" Bulletin).

On each of these deals, the bidding proceeds 1D-1H<>2H-4H.

On (a), a trump is led to East's K. He leads a trump back to West's A and a 3rd round of trumps is led. How to proceed?

On (b), West leads the K, which you duck. He then leads a trump. East wins and plays the T. You win, noting that both have followed and the 9 is still out. Should you now try to ruff two diamonds in hand or rely on a 3-3 club break? Or is there something better than these two choices?

(a)

   North
K76
QT52
A732
K5

  South
A95
J643
K4
A762

(b)

   North
J6
KQJ5
K732
K63

  South
A75
8432
A4
A742

For answers, see the Column 10 pdf file. There is a common theme and some very useful theory!


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