Final KO decided on slams and game swings (as many KOs are)...some bid well, some played well and some against the odds

Jack's margin of 23 IMPs over 64 boards can be found, like in most close matches, on a few big swing deals.  Often one lucky board is the difference between winning and losing.

Five swing boards and one flat grand from the final KO follow:

Board 2 of the third quarter produced a swing of 16 IMPs in favor of Jack.

Final Q3 Board 2
Dealer: East
Vul: N/S
♠ Q 7 3
 10
 A 10 9 8 6
♣ A Q 9 7
♠ 9 8 6 5 2
 A 9 8 6
 Q 7
♣ J 8
   
W   E
   

 K Q 7 4 3 2
 K 5 4
♣ K 6 5 4
♠ A K J 10 4
 J 5
 J 3 2
♣ 10 3 2

Table 1

N/S: Jack   E/W: WBridge5

West North East South
WBridge5 Jack WBridge5 Jack
1  1 ♠
2  3  Pass 4 ♠
Dbl Pass Pass Pass

 

Trick Lead 2nd 3rd 4th
1. W  A 10 7 5
2. W ♣ J Q K 2
3. E ♣ 4 10 8 7
4. S  J 6 ♠ 3 2
5. N ♠ Q  3 4 2
6. N ♠ 7  4 J 5
7. S ♠ 10 6  6  4
8. S ♠ K 8  8  Q
9. S ♠ A 9  9 ♣ 5
10. S  2 7 A 5
11. N ♣ 9 6 3  Q
12. N ♣ A  K  3  8
13. N  10 K J  9

Made 4: NS +790

Table 2

N/S: WBridge5   E/W: Jack

West North East South
Jack WBridge5 Jack WBridge5
1  1 ♠
3  3 ♠ 4  Pass
Pass 4 ♠ 5  Pass
Pass Dbl Pass Pass

Pass

 

Trick Lead 2nd 3rd 4th
1. S ♠ A 2 7  7
2. E  4 2 Q A
3. N ♣ A 4 2 8
4. N  10 K 3 7
5. E  Q 5 6 10
6. E  5 J  8 6
7. W ♣ J 7 K 3
8. E ♣ 5 10  9 9
9. W ♠ 5 3  2 4
10. E ♣ 6 ♠ 10  A Q
11. W ♠ 9 Q  3 J
12. E  K J ♠ 6  8
13. E  4 ♠ K

♠ 8

 9

Made 5: E/W +650
and 16 IMPs to Jack

 

Even after HA lead almost any defense (trump or Q return or duck of ♣K) will hold declarer to 9 tricks.  The contract should be defeated except for the actual play of the continuation of ♣J won by East's ♣K at trick two.

At table 1, Jack (N) had room to make a limit bid and Jack (S) was aggressive in jumping to 4♠.  With five trumps WBridge5 (W) ventured a double and kept WBridge5 (East) from saving in 5H.  At Table 2, Jack's (W) preempt kept WBridge5 (N) from showing a better hand.  Jack (E) bid 4 and then 5 on distribution, not giving Jack (W) a chance to double.  While the timing of the bids had some random influence at both tables, Jack clearly made better bidding decisions especially considering the vulnerability, and was rewarded with 16 IMPs.

A well bid slam by WBridge5 on board 11 of Q1 gained 9 IMPs.

Final Q1 Board 11
Dealer: South
Vul: None
♠ J 9 3
 K Q 9 4 2
 8 4
♣ Q 9 6
♠ A 6 5 4
 6 5
 7 6 5
♣ A J 8 7
   
W   E
   
♠ K Q 8
 A 7
 A K J 10 3 2
♣ K 10
♠ 10 7 2
 J 10 8 3
 Q 9
♣ 5 4 3 2

Table 1

N/S: Jack   E/W: WBridge5

West North East South
WBridge5 Jack WBridge5 Jack
Pass
Pass Pass 2 ♣1 Pass
2  Pass 3  Pass
4  Pass 4  Pass
4 ♠ Pass 4 NT Pass
5 2 Pass 6  Pass
Pass Pass
1 22-23 total points (2 game forcing)
2 two of five key cards without trump queen

 

Trick Lead 2nd 3rd 4th
1. N  K A 8 5
2. E  A 9 6 4
3. E ♣ K 3 8 9
4. E  K Q 5 8
5. E ♣ 10 4 A 6
6. W ♠ 4 3 Q 2
7. E  2 ♣ 2 7  2
8. W ♣ J Q  3 5
9. E ♠ 8 7 A 9
10. W ♣ 7  4  7  3
11. W  6 9  10 10
12. E  J ♠ 10 ♠ 6 ♠ J
13. E ♠ K  J 5  Q

Made 7: E/W +940

Table 2

N/S: WBridge5   E/W: Jack

West North East South
Jack WBridge5 Jack WBridge5
Pass
Pass Pass 2 1 Pass
2 ♠ Pass 3  Pass
3 NT Pass Pass Pass

 1 very strong one suited, not game forcing (2♣ game forcing)

opening lead  4, Made 7: E/W +520
and 9 IMPs to WBridge5

 

6 makes if the Q drops and has chances if the Q doesn't drop even with a heart lead (♣Q held doubleton or tripleton; hearts 3-3). 7 is down, of course, if the Q doesn't drop, and has chances if the Q drops (♣Q held doubleton or tripleton; hearts 3-3; South with four or more clubs to the queen and four hearts).  3NT could go down.  This might be a case of 2NT or 6NT or 7NT as with the Q dropping there are added squeeze chances that don't exist if the Q doesn't drop.

WBridge5 made a good bidding decision to reach the best contract, 6.  WBridge5 and Jack play 2♣ and 2 opening reversed as far as game forcing. Both treated the East hand as non-game forcing, but WBridge5 (W) made a good decision to bid 4 over 3 while Jack (W) bid 3NT over 3.

A better choice of 7 card suits for trump produced a 14 IMP swing for Jack.

Final Q2 Board 2

Dealer : East
Vul: N/S
♠ A J 8 7 5 3 2
 
 K 4
♣ Q 9 7 5
♠ Q 9 4
 K Q 9 6 3
 Q J 3
♣ 6 4
   
W   E
   
♠ K 6
 2
 A 10 9 8 6 5 2
♣ K 8 2
♠ 10
 A J 10 8 7 5 4
 7
♣ A J 10 3

Table 1

N/S: WBridge5 E/W: Jack

West North East South
Jack WBridge5 Jack WBridge5
1  1 
Pass 2 ♠ 3  4 
Pass Pass Pass

Opening lead Q, Down 2: E/W +200

Table 2

N/S: Jack   E/W: WBridge5

West North East South
WBridge5 Jack WBridge5 Jack
1  1 
1 NT 4 ♠ Pass Pass
Dbl Pass Pass Pass

 

opening lead 2, losing 1diamond and two trump, Made 4: N/S +790
and 14 IMPs to Jack

 

Who ever jumps to 4 first gets to play it.  At table 1, West made a good decision to not double 4H, as North would run to 4S.

A slightly against the odds vulnerable slam by Jack produced a 13 IMP gain.

Down one would have given WBridge5 13 IMPs and the crown!

Final Q2 Board 3
Dealer: South
Vul: E/W
♠ 10 5 3
 J 10
 9 7 3 2
♣ K 9 8 5
♠ A 8 7 4 2
 A Q 6
 J 5
♣ J 10 6
   
W   E
   
♠ K Q 6
 5 3 2
 A K 10 6
♣ A Q 2
♠ J 9
 K 9 8 7 4
 Q 8 4
♣ 7 4 3

Table 1

N/S: WBridge5   E/W: Jack

West North East South
Jack WBridge5 Jack WBridge5
Pass
1 ♠ Pass 2  Pass
2 NT Pass 4 ♣ Pass
4 ♠ Pass 4 NT Pass
5 1 Pass 5 NT Pass
6 ♣ Pass 6 ♠ Pass 
Pass Pass

1 2 of 5 key cards without trump queen

Trick Lead 2nd 3rd 4th
1. N ♣ 8 Q 3 6
2. E ♠ K 9 4 3
3. E ♠ Q J 8 5
4. E ♠ 6  4 A 10
5. W ♣ 10 5 2 4
6. W  J 7 6 Q
7. S  7 A 10 2
8. W  5 2 10 8
9. E  A 4  6 3
10. E  K ♣ 7 ♣ J 9
11. E ♣ A  8  Q 9
12. E  5 K ♠ 2 J
13. W ♠ 7 ♣ K  3  9

Made 6: E/W +1430

Table 2

N/S: Jack   E/W: WBridge5

West North East South
WBridge5 Jack WBridge5 Jack
Pass
1 ♠ Pass 2  Pass
2 NT Pass 3 ♠ Pass
4 ♠ Pass Pass Pass

Opening lead ♣5, Make 6: E/W +680
and 13 IMPs to Jack

The probability of making 6♠ is 37.4% (50% of the 67.8% of the times trumps are 3-2, plus 12.5% of the 28.3% of the times trumps are 4-1; plus none of the 3.9% of the times trumps are 5-0.).  The so called "rub of the green" in bridge!  A long match can be decided by one slightly lucky deal.  Of course, the luck tends to balance out and without a complete analysis it can't be determined which side had the better of it.

The last board of the match shows an interesting inference that humans sometimes get right and sometimes get wrong but robots always get wrong.

The play often depends on declarer's estimate of the level of an opponent's play.  Robots don't make such a judgment.

Final Q4 Board 16

Dealer: West
Vul: E/W
♠ K J 7 6 5
 2
 K Q 4 2
♣ A 9 7
♠ 9 8
 A 9 5 3
 J 8 7 6 5
♣ K 10
   
W   E
   
♠ 10 4
 K Q J 8 7
 10 3
♣ 6 4 3 2
♠ A Q 3 2
 10 6 4
 A 9
♣ Q J 8 5

Table 1

N/S: WBridge5   E/W: Jack

West North East South
Jack WBridge5 Jack WBridge5
Pass 1 ♠ Pass 2 NT1
Pass 3 ♣2 Pass 3 ♠3
Pass 4 ♠ Pass Pass
Pass
1 Jacoby 2Alert. 3Alert


Opening lead K, Made 5: N/S +450

Table 2

N/S: Jack   E/W: WBridge5

West North East South
WBridge5 Jack WBridge5 Jack
Pass 1 ♠ Pass 2 NT
Pass 3 ♣ Pass 3 
Pass 3 NT Pass 4 ♣
Pass 4 ♠ Pass 4 NT
Pass 5  Dbl 6 ♠
Pass Pass Pass

 

Trick Lead 2nd 3rd 4th
1. E  K 4 5 2
2. E  8 6 A ♠ 7
3. N ♠ 5 4 Q 9
4. S  10 3 ♠ 6 7
5. N ♠ J 10 2 8
6. N  2 10 A 5
7. S  9 J K 3
8. N  Q  J ♣ 5 6
9. N ♠ K  Q A  9
10. S ♣ J K A 2
11. N ♣ 7 3 8 10
12. W  7 4 ♣ 4 ♠ 3
13. S ♣ Q  8 9 6

Down 1: E/W +50
and 11 IMPs to WBridge5

The play comes down to finding the ♣10.  The holdings that matter to declarer are West holding ♣ K, ♣ K 10, K x and K x x x.  With ♣ K x x, West will always duck the king and defeat the game.  With K x x x, West will never cover with the king as the 10 will show up.  With K 10, West will always cover.  With K x?  If it is known that West always covers with K x declarer will always get K x x x right (when the king doesn't appear play for the K x x x as opposed to K x) and have a guess for K 10, K x when it does appear, with the finesse of the 10 four times as likely as the drop of the 10.  If it is known that West never covers with K x then declarer will always get K 10 right (except for singleton king) and have a guess for K x and K x x x when the king doesn't appear.  If defender assumes, from K x, that if covering with the king, the declarer will always finessing for the 10, then defender will never cover from K x.  If declarer knows this is defender's tendency, then declarer will always get K 10 right (again, except for the singleton king)!  A matter of game theory (judging your opponent's tendency and with what probability) which the robots don't do!  The robots will always finesse for the 10 when the king is played and sometimes play the K from K x if only using double dummy techniques as double dummy either card loses (it is assumed that declarer will never go wrong).  In human play, with two known experts against each other, duck from K x most of the time (Edgar Kaplan would give the percentage quite accurately (80% of the time?)...as he did in his famous "The Deep Nine" article (The Bridge World, October 1973).

An excellent grand was bid and made at both tables.

Final Q3 Board 11

Dealer: South
Vul: None
♠ 3
 8 6 4
 10 8 6 4
♣ Q 9 6 5 2
♠ K 7 5 2
 A
 A K Q 7 2
♣ A 10 8
   
W   E
   
♠ A Q 10 9 6
 Q J 10 9 5
 5 3
♣ K
♠ J 8 4
 K 7 3 2
 J 9
♣ J 7 4 3

Table 1

N/S: Jack   E/W: WBridge5

West North East South
WBridge5 Jack WBridge5 Jack
Pass
1  Pass 1 ♠ Pass
4 1 Pass 4 NT Pass
5 2 Pass 5 NT Pass
6 3 Pass 7 ♠ Pass
Pass Pass

1singelton or void; 2 1 or 4 key cards; 3 one king

Table 2

N/S: WBridge5   E/W: Jack

West North East South
Jack WBridge5 Jack WBridge5
Pass
1  Pass 1 ♠ Pass
4 NT Pass 5 ♣ 1 Pass
5  Pass 5 NT 2 Pass
7 ♠ Pass Pass Pass

1 one key card; 2 trump queen and club king (one king, not a heart)

Made 7 at both tables, E/W +1510, no swing

Final Q4 Board 3

Table 1

Dealer: South
Vul: E/W
♠ 10 7 6 3 2
 10
 7 4 3 2
♣ 10 5 4
♠ Q J 9 8
 4
 A K 6
♣ A Q J 7 2
   
W   E
   
♠ A 5
 A K J 7 6 5 3 2
 J 9
♣ K
♠ K 4
 Q 9 8
 Q 10 8 5
♣ 9 8 6 3
West North East South
Jack      WBridge5 Jack      WBridge5
Pass
1 ♣ Pass 2  Pass
2 ♠ Pass 3  Pass
3 NT Pass 4 NT Pass
5  Pass 5 ♠ Pass
6 ♣ Pass 6  Pass
Pass Pass
opening lead 8

Making 12 tricks, E/W +1430

Table 2

West North East South
WBridge5 Jack      WBridge5 Jack     
Pass
1 ♣ Pass 2  Pass
2 ♠ Pass 3  Pass
4 NT Pass 5 ♣ Pass
6 NT Pass Pass Pass

opening lead 7

down 3, E/W -300

17 IMPs to Jack

Keen analysis of this hand can be found in the New York Times Bridge Column, by Phillip Alder.  In summary...
At table 1, declarer played a heart to the ace at trick 2.  When South followed, declarer was assured of 12 tricks.  A finesse at trick two would guarantee the contract against a four card heart holding by North, barring an unlikely ruff at trick three.  At table two, Wbridge5 would be assured of the contract with a heart finesse at trick two.  Instead declarer took a spade finesse at trick two and went down when the hearts did not come home.