9th Annual World Computer-Bridge Championship

THE 9^th ANNUAL WORLD COMPUTER-BRIDGE CHAMPIONSHIP

Estoril, Portugal

October 25-30, 2005

The 9th annual World Computer-Bridge Championship, sponsored by the American Contract Bridge League (ACBL) and the World Bridge Federation (WBF), was held in Estoril, Portugal alongside the WBF’s World Team Championships. Six of the best bridge-playing software programs, or robots, competed for the 2005 computer-bridge world champion title.

History

The ACBL inaugurated an annual computer-bridge championship in 1997 as a way of encouraging computer-bridge software developers to accelerate their robots’ development to expert class, with the hopeful result of more software development for educational purposes and generally promote bridge. The WBF supports this event and it has become a joint venture. This year’s championship was dedicated to the memory of Alan Truscott, bridge historian, New York Times Bridge editor, and world-class player, who encouraged me to organize this championship ten years ago.

Since its inception in 1997, the championship has been held every year at an important human international bridge event. The first eight championships were held three times at ACBL North American Bridge Championships, four times at WBF World Championships and once at the European Bridge League’s first European Open Championship. For a complete history and details of previous championships go to ny-bridge.com/allevy/computerbridge or computerbridge.com.

Technical remarks

A bridge “table” consists of a central server, or Table Manager (TM), and four connecting computers that “seat” the robots. The TM distributes the four hands of each board to the robots. Play proceeds automatically with the TM receiving and passing information to the robots and recording the play. This year P4 3 GHz/512 MB PCs were used, running under Windows XP. The speed of play was set at two minutes per pair per deal, approximately half that of human play.

Without getting into the details, most of the robots are programmed with a combination of knowledge-based AI (sets of rules) and search-based AI (simulations).

Preparation

This is very much a group effort between the ACBL, the WBF, robot developers and myself as organizer. An administrative committee sets the Conditions of Contest (CoC) with input from the competitors and bridge experts.

It is important that the developers understand the opponent robots’ methods well in advance of the competition so that they can prepare and program defenses. In computer-bridge play the developers need time to enter detailed information about their opponents methods and program bidding defenses. Contestants are required to submit a Convention Card (CC) with their bidding and carding understandings one month before the competition. Since this information is stored in the robots’ memories before play begins, few explanations (alerts) are necessary during play. In the instances where explanations are required by the CoC, the pertinent information is manually input into memory and play continues.

Play format

The competition is in the form of team matches, with a team’s four identical robots seated N and S at one table and E and W at the other table. A match, or part of a match such as a 16-board segment, is played sequentially, first at one table and then at the other table.

This six-day event started with a 40-board round-robin, played in halves, with the top two robots advancing to a 64-board knockout (KO) final with carryover. The round-robin was scored on an international 30-VP scale, with the winner receiving a maximum of 25 VPs for a 69 or more IMP victory. To earn a carryover in the final KO match, a robot must both win its head-to-head round-robin match against its KO opponent and end higher in the overall standings. The carryover is the lesser of the two VP differences.

The competitors

With six teams entered, the smallest field to date, this was still one of the strongest fields of robots ever competing. Four-time defending champion, Jack (The Netherlands), was the favorite, with Bridge Baron (USA), the 1997 champion and 2003 and 2004 finalist and WBridge5 (France), the 1999 and 2002 finalist, losing to Jack in 2002 by 1 IMP, expected to threaten Jack’s recent domination. Other competitors were Q-Plus Bridge (Germany), three-time finalist, losing by 2 IMPs to Meadowlark (USA) in 2000, Micro Bridge (Japan), 2001 runner-up, and Blue Chip Bridge (U.K.).

The competition

The round-robin ended with Jack topping all competitors with 111 VPs. WBridge5, 20 VPs behind at 91VPs, would play Jack for he title. Q-Plus Bridge made a strong finish but fell short with 83 VPs. Micro Bridge was fourth with 70 VPs, followed by Bridge Baron with 48 VPs and Blue Chip Bridge with 37 VPs. To show the tightness of the competition, or possibly the randomness of short matches, even though Blue Chip Bridge finished last, it won two matches, 96-93 against last year’s finalist, Bridge Baron, and 116-110 against this year’s eventual champion, WBridge5.

The robots, their developers and the final round-robin standing are shown in Table 1. Table 2 shows the IMP/VP results of each round-robin match and the round that each match was played. Gérard Joyez operated Q-Plus Bridge.

Table 1. Robots, developers and round-robin standing

Robot	Developers	Country	VPs
Jack	Hans Kuijf, Wim Heemskerk and Martin Pattenier	The Netherlands	111
WBridge5	Yves Costel	France	91
Q-Plus Bridge	Hans Leber	Germany	83
Micro Bridge	Tomio and Yumiko Uchida	Japan	70
Bridge Baron	Stephen Smith, George Yanakiev, Jason Rosenfeld and Tom Throop	USA	48
Blue Chip Bridge	Ian Trackman and Mike Whittaker	UK	37

Table 2. Round-robin match results

Jack

Bridge Baron

WBridge5

Micro Bridge

Q-Plus Bridge

Blue Chip Bridge

Position

VPs

Jack IMPs

VPs

117-53

24-6

50-57

14-16

102-48

23-7

116-40

25-5

163-37

25-0

111

Bridge Baron

53-117

6-24

69-130

6-24

67-88

12-18

56-98

9-21

93-96

15-15

WBridge5

57-50

16-14

130-69

24-6

89-73

20-10

89-73

17-13

110-116

14-16

Micro Bridge

148-102

7-23

88-67

18-12

88-127

10-20

80-112

11-198

104-40

24-1

Q-Plus Bridge

40-116

5-25

98-56

21-9

73-89

13-17

112-80

19-11

176-23

25-0

Blue Chip Bridge

37-163

0-25

96-93

15-15

116-110

16-14

40-104

6-24

41-176

0-25

Some of the boards played in the second half of the round-robin were the played earlier in the Bermuda Bowl/Venice Cup/Senior Bowl world championship round-robin. Four boards from the fifth human round-robin follow. As the Bermuda Bowl played 20-board matches and the Venice Cup and Senior Bowl played 16-board matches, board 18 was only played in the Bermuda Bowl.

Board 18 Dlr: East Vul: N-S	North ª Q 9 5 3 © A 6 3 ¨ A 3 2 § A Q 4
West ª --- © 10 9 5 4 ¨ K J 10 9 § K 10 9 5 3		East ª K 10 8 7 © K 7 2 ¨ 6 5 4 § J 7 2
	South ª A J 6 4 2 © Q J 8 ¨ Q 8 7 § 8 6

The robots played in 4ª at all six tables. In the Bermuda Bowl, 4ª was played 14 times, 3NT by North 7 times, and 3ª once.

The play at two tables is mentioned here. If the defense slips, 4ª can be made on a non-diamond lead by East. At one table Q-Plus Bridge won a heart lead by East with the ©Q, took a club finesse, a spade to the ªJ, §A, club ruff, ©A and a heart to East’s King, leaving this position:

	North ª Q 9 5 © --- ¨ A 6 3 § ---
West ª --- © --- ¨ K J 10 9 § K 10		East ª K 10 8 © --- ¨ 6 5 4 § ---
	South ª A 6 4 © --- ¨ Q 8 7 § ---

East exited with a diamond. 4ª is now cold if East has the ¨K and cannot be made, with best defense, if West has the ¨K. If East has the ¨K, declarer’s winning line would be, ¨Q, followed by the ¨A, exiting with a diamond, then ducking a spade to East. However, Q-Plus Bridge played West for the ¨K and ducked to the ¨9. West went wrong by returning the ¨10 rather than a club. Declarer ducked to the ¨Q, then won the ¨A and ducked a spade, endplaying East.

In another match, on a club opening lead, WBridge5 found itself in the same end position as shown above but with North on lead. WBridge5, not allowing for an opponent error, played best by playing the ¨A and a diamond toward the ¨Q, going down on the lie of the cards, but only one-down when it endplayed East in trumps.

All six declarers played in 4ª, with Q-Plus Bridge making, as shown, and four others going one-down.

Interestingly, of the 15 times that the contract was played in spades in the Bermuda Bowl, declarer took only eight tricks 7 times, going –200 in 4ª and –100 in 3ª. On this board the robots were less imaginative than the experts, never playing in 3NT, and declared better than the experts, only taking less than nine tricks once in six contracts.

Board 5 from the same set follows:

Board 5 Dlr: North Vul: N-S		North ª K 8 5 4 © J 8 7 ¨ J 10 8 § K 6 2
West ª Q 10 7 6 © K Q 4 ¨ 9 7 3 § 9 8 5				East ª J © 10 9 5 3 2 ¨ A K § A Q 10 7 4
		South ª A 9 3 2 © A 6 ¨ Q 6 5 4 2 § J 3
	West		North		East	South
	WBridge5		Micro Bridge		WBridge5	Micro Bridge
	---		---		1©	Pass
	2©		Pass		3§	Pass
	3©		Pass		4©	All Pass

Micro Bridge’s §J lead resulted in +450 for WBridge5.

A simulation shows that, after 1© – 2© with the opponents silent, game is better than 50% and if partner doesn’t accept, 3© will almost always make (game will still make over 25% of the time), and if partner accepts, game will make most of the time. The risk of a game-try is nil as going down in 3© is offset by South possibly entering the auction, if East passes 2©, and going plus in a spade contract.

WBridge5 bid to 4© as shown. This appears to be a faulty simulation. On a similar auction, Jack, against Bridge Baron, reasonable (and correctly) passed 3©. 2© was played at the other four tables. Micro Bridge and Blue Chip Bridge, playing four-card majors, bid 1©-1ª/2§-2©/Pass (with West holding 4 or more spades and only three hearts, game is less than 50% with the risk of going overboard greater than 25%, therefore pass is the percentage bid), as did Bridge Baron, playing five-card majors (with West holding 2 or three hearts pass is the percentage bid). Q-Plus Bridge, playing 5-card majors, bid 1©-2©. Given their methods, four judged well with Micro Bridge, Blue Chip Bridge and Bridge Baron passing, and Jack stopping in 3©), Q-Plus Bridge was too conservative and WBridge5 was too aggressive.

It is interesting to compare the robots’ play to that of the experts in the world championship events. In the Bermuda Bowl, 4© was bid twelve times and made ten times (miss-guessing the ©J at two tables, I presume), 3© was played nine times, and 3§ was played once (too aggressive, assuming a variety of systems). In the Venice Cup, 4© was bid and made nine times, 3© was played three times, 2© was played five times, and there were five other inferior contracts, 2NT, 3NT, 2§, 2ª by N (-2), and 3§ (average aggressiveness with too many accidents). In the Senior Bowl, 4© was bid and made eight times, 3© was played five times, and 2© was played nine times (average aggressiveness, assuming a variety of systems). In our championship, 4© was bid and made once, 3© was played once, and 2© was played four times.

One trademark of the Bermuda Bowl experts is reaching slim games even when non-vulnerable.