Humans versus Jack (2)

Computer Bridge 2; World Champion Jack in Action

To gauge the playing strength of Jack, we matched him against seven strong Dutch pairs. This instalment covers the first three matches.

To get quick results we decided to play 'Instant IMPS.' The boards had been played about five years ago in the First Division and none of the players had seen them before. We selected complete sets and played them in the order in which they had been played originally. Each pair of human chose which of four sets of 28 boards to play and whether to sit North-South or East-West. As each human pair played different boards, a fair comparison among human pairs was not possible, but this arrangement avoided the dullness of having the same deals played seven times.

The playing conditions were as normal as possible. Martin Pattenier operated the computer while Hans Kuijf and I bid and played for Jack by following the instructions Martin read from the screen.

Before the first match the Jack team was a bit nervous. Were we too optimistic to challenge the best of the Netherlands' pairs? What if all of them beat Jack decisively? After the first three matches we gave a sigh of relief. Two wins and one small loss. The experiment was a big success already!

In the match against Hanneke Kreijns & Just vd Kam, Jack's wide-range preempts proved effective and had a major influence.

South deals None 7 6 K 9 4 Q 10 8 4 A K 5 3 10 9 3 A Q J 10 8 6 5 3 - 7 6 N W E S V 2 K J 9 7 6 3 Q J 10 9 2   A K J 8 5 4 2 7 A 5 2 8 4

West HK North JackN East JvdK South JackS - - - 4 5 double pass pass pass

After 4 Hanneke Kreijns (daughter of living legend Hans Kreijns) looked at her eight card heart. 5 is understandable but it went down four doubled. The NS average was +430 and Jack won 9 IMPs.

A few boards later Jack opened another pre-empt. This time EW were a bit more cautious.

South deals North/South A 7 2 Q 8 7 5 4 10 7 3 4 3 K 10 4 3 J 10 9 A Q J 9 7 5 N W E S Q J 9 6 K 2 9 6 5 A K 6 2   8 5 A 6 3 K Q J 8 4 2 10 8

West HK North JackN East JvdK South JackS - - - 3 pass pass pass

This time West's caution missed a laydown 4. In 3 Jack misguessed hearts and went down two, but still won 6 IMPs.

So the first match gave a nice feeling. But what about Janssen & Top, the reigning Dutch Pairs champion? This time Jack's adventurous preemption ended less fortunately. With both sides vulnerable, Jack opened 3 and bid 5 on his own after the opponents reached 4. In Jack's commercial version this undisciplined action is not allowed, but we played these matches with the WC-settings. This means that a preemptive bidder is allowed to take another action. That may sound strange, but our experience is that this isn't such a bad strategy, at least not for computers. On this board, however, it backfired. 4 was making, all right, but 5 went down 1100. Most of the boards were a bit dull and Janssen & Top were very likely to score a small victory. But then, just before the end, one of them made a typical human mistake: he forgot an agreement...

From the match against Eric Janssen and Jeroen Top:

North deals North/South A K 9 8 2 A Q 8 7 5 3 2 10 5 4 2 4 K J 10 9 A K 9 5 3 N W E S K Q J 10 8 10 7 6 6 8 7 4 2   9 7 6 3 A Q J 5 3 4 Q J 6

West JackW North JT East JackE South EJ - 1 1 2 3 4 pass pass double pass pass pass

The bidding requires some explanation. Only a few days earlier Janssen&Top started playing the Bocchi-Duboin transfers after an overcall, so 2 showed hearts. Alas, Top had forgotten ...

JackW's 3 showed a constructive hand with spade support (13-15 support points) and instead of showing his heart support, Top bid 4. As Top hadn't alerted 2, Janssen knew there was a misunderstanding. Being a very ethical player, he passed, and JackW had visions of big numbers. After all, partner overcalled and he had AK and KJ109 in trump. So he doubled. But 4 could not be beaten and despite missing the heart game, Janssen & Top lost no IMPs. The NS average was +700 and +710 was a push.

Jan van Cleeff and Vincent Kroes soon noticed that Jack played a lot better then they had expected. About halfway through the match, van Cleeff had to play a contract that could not be made. Van Cleeff kept thinking and thinking. Meanwhile, Kroes glanced at the screen, where a double-dummy analyzer showed 'two off,' so he made a little joke: "Jack says you can make it!"

Van Cleeff plunged into deep thought. After a while, Kroes felt pity and rescued him. Playing well is not always an advantage. Van Cleeff & Kroes cleverly gave Jack an extra option and he took the best technical line. No good!

From the match against Jan van Cleeff and Vincent Kroes:

South deals East/West 10 Q 7 3 2 Q J 10 2 J 6 4 2 8 3 2 K B 9 8 6 A Q 10 8 3 N W E S Q 5 4 8 6 5 4 A 3 K 9 7 5   A K J 9 7 6 A 10 9 K 7 5 4 -

West VK North JackN East JvC South JackS - - - 1 pass 1SA pass 2 * pass 2 * pass 3 pass 4 pass 4 pass pass pass

Some explanation: 2 was conventional and could be based on a strong hand (a bit like Cole). 2 was a relay (denying long hearts). 3 was game-forcing with at least five spade and at least four diamonds. 4 showed a sixth spade and suggested a final contract.

Against 4 Kroes led the 6. Van Cleeff took his ace and returned a diamond. To retain his optimal play in the heart suit, Jack won in hand and played AK. The queen of trumps didn't drop, so Jack surrendered a spade. Van Cleeff returned a club (of course the defence didn't touch hearts). Jack ruffed and had to play hearts himself.

South deals East/West - Q 7 3 Q B J 6 - K B 9 A Q 10 8 N W E S - 8 6 5 4 - K 9 5   J 9 A 10 9 5 4 -

Seeing all four hands you might wonder how Jack could go wrong.

The ace of hearts and a heart, or a low heart towards dummy first would succeed. Everything works. But watch out! Double-dummy analysis is a well- known pitfall. Analysing objectively is not so easy, at least for humans, when all the cards are visible. However, Jack always plays according to the probabilities. With this holding he 'knows' the best way to play hearts is to finesse through East twice. That is why he kept two diamond entries to dummy. Without a blink he crossed to the Q and led a heart towards the nine. Kroes took his jack and return a club. Jack ruffed, entered dummy via the J and led a heart towards his ten...
Oh, well: "Down one is good bridge!"

The chosen line works if the Q drops in two rounds or East has a heart honor. The alternative is to cross to dummy in the second trick and finesse in trumps. If this fails declarer has to guess the hearts. Jack's line is definitely superior, but fails on this particular hand. A small disappointment for the Jack team, but the program didn't seem to mind.

The results of the first three matches:

Jack	-	Hanneke Kreijns & Just vd Kam		74 - 53
Jack	-	Erik Janssen & Jeroen Top		43 - 51
Jack	-	Jan van Cleeff & Vincent Kroes		61 - 46

Next time Jack plays against Paul Felten & Eric van Valen, Ton Bakkeren & Huub Bertens and Vincent Ramondt & Berry Westra. Will he survive?

Wim Heemskerk