World Computer-Bridge Championship, XII

Wbridge5 and Jack battled for the championship.  It started with an 18 Imp carryover for Jack based on round-robin results, and ended with Wbridge5 defeating Jack 172-157.

The final difference of 15 Imps could have been gained in two swing boards.  We will look at the swing boards, with swings of 10 Imps or more.

Final Score Sheet

Final boards: quarter 1, quarter 2, quarter 3, quarter 4

Board 1, 1st quarter.  Dealer North. Vulnerable None.
	♠ A J 6 ♥ K Q 8 2 ♦ Q 10 9 3 2 ♣ 8
♠ 10 9 2 ♥ A J 9 6 5 ♦ 6 ♣ J 10 7 6		♠ 8 7 ♥ 7 4 ♦ J 8 7 5 4 ♣ K Q 6 2
	♠ K Q 5 4 3 ♥ 10 3 ♦ A K ♣ A 9 4 3

Wbridge5 reached the reasonable spade slam.  Against a ♣ J lead, and the duck of the ♥A once, the bad diamond break did not allow Wbridge5 to ruff a club and take two heart winners and three diamond winners.  Down one, and an 11 Imp pickup for Jack.

Board 8, 1st quarter.  Dealer West. Vulnerable None.
	♠ 2 ♥ 10 9 6 ♦ K Q J 9 8 6 2 ♣ A 4
♠ 10 5 3 ♥ A Q J 8 5 ♦ A 10 ♣ Q 7 6		♠ A K 6 4 ♥ 4 3 ♦ 4 ♣ K J 9 5 3 2
	♠ Q J 9 8 7 ♥ K 7 2 ♦ 7 5 3 ♣ 10 8

The traditional preempt with a seven-card suit is 3, and worked better for Wbridge5 than Jack's preempt of 4♦.  Preempts cause problems, but have risk.  At table 1, West tried 3NT, which failed.  Any diamond preempt makes it difficult for E-W to reach a good club game or lucky club slam.  At table 2, in 4♦x, Jack could only make seven tricks, 6 diamonds and the club A, for -500 and a 12 Imp pickup for Wbridge5.

Board 14, 1st quarter.  Dealer East. Vulnerable None.
	♠ 10 ♥ Q 7 2 ♦ Q J 10 8 6 3 ♣ A 6 5
♠ A 9 4 2 ♥ 9 ♦ K 9 4 ♣ K 10 8 7 3		♠ K J ♥ A J 10 6 5 4 3 ♦ 7 ♣ J 4 2
	♠ Q 8 7 6 5 3 ♥ K 8 ♦ A 5 2 ♣ Q 9

Edgar Kaplan used to say that an opening of 4♥  was a transfer to 4♠...by the opponents.  Jack followed the adage, for -500, and 11 Imps to Wbridge5.  I'm not sure Edgar would approve of the 4♠ bid in this case.  At the other table, Jack opened 1♥, and the auction proceeded, 1♥-1♠-2♣-2♦-All Pass, for +90 for Wbridge5.

Board 4, 2nd quarter.  Dealer West. Vulnerable Both.
	♠ 10 9 8 6 ♥ A J 8 7 3 ♦ - ♣ K J 5 3
♠ Q J 7 5 4 ♥ 5 2 ♦ 4 3 ♣ A 9 8 6		♠ A K ♥ 10 9 4 ♦ K 9 8 7 2 ♣ 10 4 2
	♠ 3 2 ♥ K Q 6 ♦ A Q J 10 6 5 ♣ Q 7

At Table 1, Jack led the ♠A and did not switch to trumps at trick two, +620 for Wbridge5.  At table 2, Jack, should either have bid 2♥ over 1♠ or 3♥ over 3♦ to reach 4♥.  Against 3NT, East started with ♠A, ♠K, and a club to West's ace for down 2, +200, and 13 Imps for Wbridge5.

Board 5, 2nd quarter.  Dealer North. Vulnerable N-S.
	♠ A K 9 3 ♥ A 7 6 2 ♦ 7 ♣ Q J 7 2
♠ Q 8 7 4 2 ♥ Q 10 9 4 ♦ K Q ♣ 10 9		♠ 5 ♥ J 8 5 3 ♦ 9 6 5 3 2 ♣ K 5
	♠ J 10 6 ♥ K ♦ A J 10 8 ♣ A 8 6 4 3

 3♣ forcing; 5♠ 2 key + ♣Q

* 2♣ inverted

At table 1, Wbridge5 found the excellent 6♣ contract.  At table 2, Jack bid 3NT over 2♥ rather than try to investigate further. 6♣ made and 3NT made 5.  12 Imps to Wbridge5.

Board 8, 2nd quarter.  Dealer West. Vulnerable None.
	♠ 5 ♥ K 8 ♦ K Q 10 9 6 3 2 ♣ 9 6 4
♠ J 9 ♥ A 10 9 5 4 ♦ A 5 4 ♣ A J 7		♠ K 8 6 3 ♥ Q 6 ♦ J 8 7 ♣ K 10 5 2
	♠ A Q 10 7 4 2 ♥ J 7 3 2 ♦ - ♣ Q 8 3

The robots are consistent...see board 8 from the 1st quarter.  At table 1, Wbridge5 preempted with 3♦ and defended 3NT, while at table 2, Jack, once again preempted with 4♦ with a seven-card suit. This would have gone down 3, doubled, but South tried 4♠ and went down 4, doubled, for -800.  At table 1, Jack could have timed the play to make 3NT.  After the ♦K lead, low toward the ♥Q at trick two would let declarer play North for the actual hand held.  With good timing and a winning club guess, 9 tricks could have been made.  In actual play, Jack returned a diamond at trick two and went down two, -100, and 14 Imps for Wbridge5.

Board 2, 3rd quarter.  Dealer East. Vulnerable N-S.
	♠ 9 8 7 5 4 3 2 ♥ Q 7 ♦ J 2 ♣ 10 6
♠ A 6 ♥ K J 8 6 4 2 ♦ K 6 ♣A K 4		♠ K Q J ♥ 10 5 3 ♦ Q 9 7 3 ♣ J 9 2
	♠ 10 ♥ A 9 ♦ A 10 8 5 4 ♣ Q 8 7 5 3

* 2♦ strong one- suiter; 2♠ positive, waiting

At table 1, South's questionable 2NT, coupled with North's 3♠  bid, led to -800 for Wbridge5.  At table 2, the ♦J was led to South's ace, and West unblocked the ♦K.  A spade return was won with the ace.  There were possible unblocking issues with the play, so Wbridge5 played a second spade to the king...curtains...South ruffed and returned a diamond, got in with the ♥A and retuned a third diamond, promoting North's trump queen for down one and 13 Imps to Jack.

[Wbridge5 does a simulation bases on known information, but not based on the implications of the opponents' defense.  In this case, at trick three, declarer determines that it is safer to reach dummy with a second spade rather than with a second diamond.  However, South's winning the ♦A and returning a spade, strongly suggests a singleton spade.  A second tier simulation can analyze this.  For each hand generated, a second tier simulation, from the opponent's point of view, would show that South's return of a spade implies a singleton.  Best declarer play would then be to win the second trick in dummy, and return a trump to the king if South ducks.  AL]

[Yves Costel reports that Wbridge5 does not make simulations from the opponents' point of view.  "I tried double dummy but it did not improve the card play.  To achieve a real improvement, I have to make the simulation from the opponents' point of view single dummy.  It will be very time consuming.  In this case, West has to go to the dummy to play a trump. A spade is much less risky than a diamond, as the 7-1 break is only 1.3%."]

Board 3, 3rd quarter.  Dealer South. Vulnerable E-W.
	♠ 9 5 2 ♥ J 5 ♦ A K 9 7 4 ♣ A Q 6
♠ A 7 ♥ K 7 6 3 2 ♦ J ♣ 9 8 7 4 2		♠ Q 7 ♥ A Q 10 9 ♦ 10 6 3 ♣ K J 5 3
	♠ K J 8 6 4 3 ♥ 8 4 ♦ Q 8 5 2 ♣ 10

* fit-showing

Jack bid game at both tables.  Both contracts can be defeated, but both made.  Against 4♥x, North could have led the ♣A, knowing that South had a singleton, but chose the ♦A first.  North switched to the ♣A and club ruff, but it was too late for 2 club ruffs, and +790 for Jack.  At table 2, Wbridge5 made the killing lead of the singleton ♦J, declarer led to the ♣A, led a trump to the jack and ace.  West cashed the ♥K, led to the ♥A, but East tried to cash the ♣K rather than try give partner a diamond ruff, 420, and 15 Imps for Jack.

[Yves Costel reports that Wbridge5 wasn't aware that the 3♦ bid was fit-showing, and assumed that South had seven spades.  If noticed in time, a "friendly" appeal would be in order, and in these cases the opponents either agree to a replay or ask for a ruling.  This is possible in robotic play, as the robots' memory can be erased.]

Board 14, 3 rd quarter.  Dealer East. Vulnerable None.
	♠ K 7 6 ♥ 9 7 3 2 ♦ A Q J 7 6 ♣ A
♠ 9 3 ♥ K J 5 ♦ 5 2 ♠ K J 10 5 4 2		♠ A Q J 8 4 2 ♥ A Q 6 4 ♦ 8 ♣ 9 8
	♠ 10 5 ♥ 10 8 ♦ K 10 9 4 3 ♣ Q 7 6 3

The first four trick were the same at both tables, diamond lead to the ace, ♣A, diamond ruffed by declarer, ♠A.  At table 2, Wbridge5 went to dummy via ♥J, and led a second trump, +420 for Wbridge5.  At table 1, for unknown reasons, Jack tried to reach dummy with a club, North ruffed for down 1 and 10 Imps to Wbridge5.

Board 16, 3rd quarter.  Dealer West. Vulnerable E-W.
	♠ K 4 ♥ J ♦ K 6 3 2 ♣ A K Q 8 7 5
♠ Q 6 3 ♥ A K Q 9 5 3 ♦ 5 4 ♣ 4 2		♠ 10 8 7 5 ♥ 10 6 4 2 ♦ 10 8 7 ♣ 10 9
	♠ A J 9 2 ♥ 8 7 ♦ A Q J 9 ♣ J 6 3

The first two rounds of bidding was the same.  Wbridge5 North then bid 4♣, while Jack North bid a strange 3NT.  This led to 6♣ by Wbridge5, making 6 for 920, and 6NT by Jack, down 5 doubled, -1100.  19 Imps for Wbridge5, more than the winning margin.

Board 2, 4th quarter.  Dealer East. Vulnerable N-S.
	♠ 10 8 4 2 ♥ J 6 3 ♦ 9 7 3 2 ♣ 10 5
♠ 5 ♥ K Q 8 5 ♦ A K 5 ♣ 8 7 6 3 2		♠ A Q 9 7 6 3 ♥ A 10 9 4 2 ♦ J ♣ 9
	♠ K J ♥ 7 ♦ Q 10 8 6 4 ♣ A K Q J 4

At table 1 Wbridge5 stopped in 5♥, making 6 for +480.  Clones are not supposed to have bidding misunderstandings, but at table 2 is seems as if Wbridge5 East and West were on different wavelengths.  Whatever West's Dbl showed, East showed spades and hearts, and West placed the contract in 6♥, which makes.  For some unknown reason, East went to 6♠, down 3, and 12 Imps to Jack.  [Yves Costel reports a bug in his robot, which is now fixed.]

Board 9, 4th quarter.  Dealer North. Vulnerable E-W.
	♠ 9 4 ♥ Q J 9 8 ♦ J 10 8 ♣ A J 6 4
♠ J 10 8 6 ♥ 7 6 5 ♦ Q 6 ♣ 10 8 7 5		♠ A 2 ♥ K 3 2 ♦ 9 7 4 3 2 ♣ Q 9 2
	♠ K Q 7 5 3 ♥ A 10 4 ♦ A K 5 ♣ K 3

The ♦3 was led at both tables. The play at trick one determined the success of the contract.  Wbridge5 went up with the ♦A, and went after 2 clubs, 2 diamonds, and six tricks in spades and hearts.  ♣K, ♣A, spade to the queen.  ♥A and a heart to nine and king.  A better line is for declarer to not cash the ♥A first.   A better defense, and one that beats the contract, is for East to duck the second heart.  [The best line is ♦A, and a small heart to the nine at trick two.]  After winning the ♥K, East returned a diamond to partner's queen, but West didn't have a good return.  A club allows the club queen to be the ninth trick, and the actual return of a spade allowed the ♠K to be the ninth trick, and +400 for Wbridge5.  When Jack played in 3NT, the diamond lead was ducked to West's queen, and a diamond was returned.  It is easy to see that the tempo was now with the defense.  Jack now played ♣K, and club to the jack and queen, down 2 and 11 Imps to Wbridge5.

Board 10, 4th quarter.  Dealer East. Vulnerable Both.
	♠ - ♥ Q 6 3 ♦ 5 2 ♣ A K J 10 5 4 3 2
♠ A 10 3 ♥ 10 9 7 ♦ K J 10 9 7 ♣ Q 6		♠ K J 9 6 5 ♥ A K 8 4 ♦ A 6 4 ♣ 9
	♠ Q 8 7 4 2 ♥ J 5 2 ♦ Q 8 3 ♣ 8 7

In 4♠, A club was led to the ♣K and ♣A, ruffed by declarer.  The ♠K revealed the bad trump break.  Play proceeded, ♦A, diamond to the nine, heart to the ace, spade to the ten, and cashing good diamonds.  South gets two trump tricks and Jack gets 620.  At table two, Wbridge5 got to 6♦, but made a slight slip that cost the contract.  After a club ruff and three rounds of diamonds, declarer innocently leads the ♠10 toward dummy.  With the 5-0 break, declare cannot establish a fourth spade trick.  Wbridge5 should have led a low spade to the ♠K, then spade to the 10, ♠A, ♥A, ♠J now establishes the fourth spade and 12 tricks.  Down one was 12 Imps for Jack. [Wbridge5 determines the probability of a 5-0 split at less than 2%.  If North covers the spade ten the contract is made, and if not Wbridge5 will try to finesse against South.]

Board 14, 4th quarter.  Dealer East. Vulnerable None.
	♠ - ♥ A 9 5 3 ♦ J 10 9 5 ♣ Q 9 6 5 2
♠ K 10 8 7 2 ♥ Q J 4 2 ♦ Q ♣ 10 8 3		♠ Q J 6 5 3 ♥ 8 7 6 ♦ 4 ♣ K J 7 4
	♠ A 9 4 ♥ K 10 ♦ A K 8 7 6 3 2 ♣ A

* 2♣, 22+points

*  2♦, strong one-suiter; 2NT, positive, less than 2 spades, 3+ in other suits; 4♣, agreed diamonds as trump, 10-12 points in support

# I don't need the trump queen if you have 3+ trumps, at most one spade, and the heart ace

Jack found the lay-down grand, while Wbridge5 didn't explore further over 5♦.  11 Imps to Jack.