International Computer Games Association Journal          September 2004          pp. 189-193

THE 8^th ANNUAL ACBL’S WORLD COMPUTER COMPUTER-BRIDGE CHAMPIONSHIP

New York City, New York, USA

July 13-17, 2004

Alvin Levy[1]

The American Contract Bridge League’s (ACBL) 8th annual World Computer-Bridge Championship was held in New York City in conjunction with the ACBL’s summer North American Bridge Championships (NABC).  Eight of the best bridge-playing software programs, or robots, competed for the title of 2004 computer-bridge world champion.

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.  Since then progress has accelerated and the top robots have advanced significantly to the level of strong club player.

This championship has been held every year at an important human international bridge event, with me as the organizer.  The preceding seven championships were held three times at ACBL NABCs, three times at World Bridge Federation (WBF) World Championships and last year at the European Bridge League’s (EBL) first European Open Championship.  When hosting this championship, the ACBL, WBF and EBL have given both financial and organizational support.  For a complete history and details of previous championships go to ny-bridge.com/allevy/computerbridge.

Technical remarks

A bridge “table” consists of a central server, or Table Manager (TM), and four connecting computers, which “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 2.4 GHz/512 MB PCs were used, running under Windows XP.  The speed of play was set at 2 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, or sets of rules, and search-based AI, or simulations.

Preparation

This is very much a group effort between the organizer, the computer-bridge software developers and the ACBL.  The Conditions of Contest are set by an administrative committee with input from the software developers and bridge experts.

It is important that the developers understand the opponent robots’ methods in advance of the competition so that they can prepare defenses.  In human play advance notice, with unusual systems not allowed, are not necessary.  However, in computer-bridge play the developers need time to program defenses and store information about the opponent robots’ methods.  Contestants are required to submit a Convention Card (CC) one month before the competition.  This is in the form of a spreadsheet, with over 100 questions.  Once the CCs are published contestants ask each other (through email) even more detailed questions about their methods and conventions.  Since this information is stored in the robots’ memories before the competition begins, few alerts are necessary during play.  In the few instances where alerts are required the pertinent information is input into memory and play continues.

Play format

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

The five-day event starts with a 24-board round-robin with the top four robots advancing to a 64-board knockout (KO) semifinal with carryover.  The round-robin is scored on an international 30-VP scale, where the winning side receives a maximum of 25 VPs for a 52 or more IMP victory.  To earn a carryover in a KO match, a “team” 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 these two VP differences.

The competition

The round-robin ended with Bridge Baron topping all competitors with 147 VPs.  The other three teams advancing to the semifinals were Wbridge5, closely behind with 145 VPs, Jack, with 138 VPs and Micro Bridge with 131 VPs.

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.

Table 1.  Robots, developers and round-robin standing

Table 2.  Round-robin match results

Even though Q-Plus Bridge did not make the semifinals, it demonstrated fine play on this deal.  This hand occurred in the fourth round against Jack.  26 IMPs were at stake; 13 IMPs to Q-Plus Bridge if it makes its 6© contract and 13 IMPs to Jack if it fails.  Note: In every set of boards throughout the championship there were demonstrations of expert play and poor play.  The hands shown in this report demonstrate some of the expert play.

With the spade bid by South, West’s hand became bigger, and the Q-Plus Bridge robots bid to an overly aggressive heart slam.  South led a low spade.  Declarer finessed, drew trumps, eliminated diamonds and spades, cashed the §A and led a low club.  The defense was helpless and Q-Plus Bridge scored +1430.

Semifinals

In the semifinals, round-robin first place finisher, Bridge Baron, had a 14 IMP carryover against fourth place finisher, Micro Bridge, and second place finisher, Wbridge5, had a 2 IMP carryover against third place finisher, Jack.

The last time Jack played Wbridge5 in the championship KO stage was the 2002 finals.  That final was the closest KO final in computer-bridge history with Jack winning by 1 IMP.  This year Jack continued its winning ways, this time defeating Wbridge5 more comfortably, 157-118.  In the other semifinal match Bridge Baron defeated Micro Bridge 166-126.

Board 64 of the semifinals earned Jack 17 of its 39 IMP margin of victory and was a wash in the other match.

Board 64               North

Dlr: West              ª 6 5 3

Vul: E-W               © Q 10 4

                            ¨ 10 8 7 2

                            § 10 8 5

West                                        East

ª 8                                          ª A K Q 4 2

© 8 2                                       © K 9 3

¨ A K Q J                               ¨ 6 5

§ K Q J 7 6 3                          § A 4 2

                            South

                            ª J 10 9 7

                            © A J 7 6 5

                            ¨ 9 4 3

                            § 9

¹ two key cards and the §Q

² one king other than the §K

Jack found the perfect contract, 6NT by East.  Jack took thirteen tricks after the lead of the ªJ, +1470.   5NT asked for kings.  East was planning to bid 6§ if West didn't have the ¨K.  Indeed, if West has ª8 ©Q2 ¨AQJ7 §KQJ763, for example, 6§ is the superior contract.

At the other table, Wbridge5 did not reach slam.  The strong 2ª bid crowded the auction and Wbridge5 stopped in 3NT, played from the wrong side.  Jack found the deadly lead of the ©10.  Now the defenders took the first five tricks for one down.  Jack normally leads low from honor-third.  However, after simulating possible layouts, Jack saw the danger of blocking the suit and therefore chose the ©10 lead instead of the ©4. The unexpected extra bonus was one down when the ©10 lead won the trick and hearts could be continued.

In the other semifinal match, both teams arrived at 6§ by West and could have been beaten on a heart lead.

¹ two key cards and the §Q

At one table Micro Bridge was on a guess between a diamond and a heart lead, and chose a diamond.  At the other table, if Bridge Baron doubles 5© for a lead, East might bid 6NT.  Without the double North led a diamond.  6§ making 7 at both tables for a wash.

For the second year in a row Jack and Bridge Baron were playing for the championship.  There was no carryover as Jack defeated Bridge Baron in their head-to-head round-robin match and Bridge Baron finished higher in the round-robin standing.  Jack defeated Bridge Baron, 157-97, to claim the championship for the fourth year in a row.

An example of some of the good play is shown in Board 27.

Board 27           North

Dlr: South         ª Q 10 7 6

Vul: None         © K 4

¨ J 6

§ K 8 4 3

West                                        East

ª J 8 2                                     ª A 4 3

© Q 8 6                                    © A J 10 9 7 3 2

¨ 10 3                                      ¨ K 9

§ A Q 10 9 2                            § J

South

ª K 9 5

© 5

¨ A Q 8 7 5 4 2

§ 7 5

West    North    East      South

BB        Jack     BB        Jack

Jack     BB        Jack     BB

---        ---        ---        3¨

Pass     Pass     4©        All Pass

At both tables the bidding and play were identical.  The opening ª5 lead went to the ª10 and ªA.  Both declarers led a club to the §A and passed the ©6.  Next the §Q was led and both Norths defended best by not covering.  The declarers discarded a spade and continued with the §10, covered and ruffed; cashed the ©A; crossed to the ©Q and cashed the §9.  11 tricks (seven hearts, three clubs and a spade) were made at both tables for +450.

General remarks

After 296 boards Jack demonstrated the most consistent good play and the title of computer-bridge world champion is well deserved.  Bridge Baron, Wbridge5, Micro Bridge and Q-Plus Bridge also demonstrated good play.

The level of play of the top robots has greatly improved over the past seven years, with the top programs such as Jack, Bridge Baron, Wbridge5, Micro Bridge, Q-Plus Bridge and GIB (not entered in this championship for the past two years) making great progress.  Before this championship began in 1997 the best robots were barely approaching Intermediate play.  Now the best robots would be hard to beat in club play and a pair of Jack-Jack robots would be stars.  This has been demonstrated recently in matches pitting expert human players against a team of Jack robots (Marston, 2003; Kleinman and Kuijf, 2004).

For more information on this year’s championship as well as past championship results, articles and photos, go to computerbridge.com or ny-bridge.com/allevy/computerbridge

References

Marston, P. (2003).  The Australian Bridge Australia-Wide Spring Pairs Souvenir Booklet.  Australian Bridge, Vol. 34, No. 5, P. 4.

Kleinman, D. and H. Kuijf (2004).  Humand vs. Computer:  Vrijthof Maasvogels – JACK, ICGA Journal, Vol. 27, No. 1, p. 52.