ACBL/WBF 17^th World Computer-Bridge Championship
By Alvin Levy

The World Computer-Bridge Championship is held annually at a major human championship. This year’s event was held on September 23-28, 2013 at the World Bridge Federation’s 41^st World Teams Championships in Bali Indonesia.  Six of the best robots were entered, including: the two top past winners, defending champion Jack (The Netherlands) and WBridge5 (France); past champions Shark Bridge (Denmark) and Bridge Baron (USA); and many time runner-ups Q-Plus Bridge (Germany) and Micro Bridge (Japan).

The format was a 48-board round robin with the two top finishers playing for the Gold medal in a 64-board KO match. The Conditions of Contest call for a semifinal stage when there are seven or more entries, but only a final KO with six or fewer teams. Twice before, in 2001 and 2005, were there as few as six robot teams entered. The greatest number of entries was ten, in 2009.

The contestants all used the same computers, 2.9 GHz Intel Core i5 desktop PCs under Windows 7 OS.

The round robin results:

WBridge5        69.45

Jack                 60.11

Q-Plus Bridge  54.81

Micro Bridge   48.03

Shark Bridge   39.13

Bridge Baron   28.47

Board 37 from the last round robin match had the theme...bid one more!

¹ hearts and diamonds

The play started ♦K, ♦A, ♦x, ruff and over-ruff.  Declarer leads a heart to the ace and leads a trump, covering the 10 with the jack and holds the trump losers to one for down one in 5♠x. E/W -100.

At the other table,

¹ hearts and a minor

The play started the same way ♦K, ♦A, ♦x, ruff and over-ruff and again declarer had no trouble holding the trump losers to one, making 4♠. E/W +420.  11 IMPs to Jack.

In another match,

¹ hearts and diamonds

Making 5, N/S +850

The play started ♦K, ♦A, ♦x, ruff and over-ruff and again declarer had no trouble making 4♠, E/W +420.  15 IMPs to Q-Plus Bridge.

In the other match,

¹ hearts and diamonds

Made 5, N/S +850

¹ strong spade raise with heart control.

The play started ♦K, ♦A and a switch to ♥4.  South recognized that there was no need to ruff out dummy’s diamond winner. Now declarer led a spade to the jack, and had to loss two trumps for down one, E/W -100.  13 IMPs to WBridge5

^** the developers comment on their robot's choice of 5♦/5♥.

Hans Kuijf, developer of Jack, comments..."Robots are certainly less partner oriented than humans. Best bridge is probably somewhere in the middle.  Humans include partner too much and robots too little. The reason for Jack’s 5♥ bid is that it is rule based and not based on simulations. If partner is able to make the right decision based on a number of sample hands, then Jack invites partner. In this case 5♦ would tend to show longer diamonds than hearts. Humans in the South seat, however, will certainly bid 5♣ or 4NT”.

Hans Leber, developer of Q-Plus Bridge comments... "It would be nice to say that 5♥ must show 6-6, because with 6-5 it would not bid 3♣ (but possibly with 5-6 it would).  This is how Q-Plus Bridge is programmed, but after 4 ♠ the robot sees the advantage of bidding on and prefers the major over the minor without thinking, i.e., purely rule based.  In this situation I would have expected the robot to have make a simulation, but it did not because it did not consider it a choice between 5♦ and 5♥.” Hans Leber considers this a software error. “If it had run a simulation (which I did after the play) it would have selected 5♦.  So 5♥ is an error which turned out lucky.  Over South's 5♦ North would pass if West passed, but run to 5♥ if 5♦ was doubled”.

Yves Costel, developer of WBride5 comments..." WBridge5 has a rule to add one to the length of a long suit with AKQ or AQJT or AKJT.  In that case diamonds are considered longer than hearts and WBridge5 bids 5♦ ”.

Board 10 of the final round robin started the same way at all six tables, with East dealer, the bidding started 1♥ - 3 ♠ - Pass - Pass. At five tables East reopened with a Dbl.

Opening lead ♠8, making E/W +600

In one match Micro Bridge (West) bid 3NT, as shown above, and could not be stopped from taking nine tricks, while at the other table, Jack (West) bid 4♥ and went down 3 for -300 and 11 IMPs to Micro Bridge.  In another match Shark Bridge (West) bid and made 4♣ for +130 while at the other table Q-Plus Bridge (West) passed.  In 3♠x Shark Bridge played correctly by setting up a diamond trick for a heart discard before playing trumps and was +730 (only double dummy defense can beat 3♠) and 13 IMPs to Shark Bridge.  In the final match WBridge5 (East) doubled and WBridge5 (West) passed. After a heart lead, East cashed the club ace and the diamond ace on which Bridge Baron correctly unblocked the king (not needed in this particular layout) and was +730.  At the other table, Bridge Baron did not balance with a double, and WBridge5 went down one in 3♠ when declarer played on trumps before diamonds. 13 IMPs to Bridge Baron.

For a comparison to the human play, two 16-board sessions were taken from the championship round robin play (round robin sessions 1 and 14), and used in the final 16-board session of the 2^nd and 3^rd robot round robin.  The human competition consisted of 22 teams in each of three categories, Open (Bermuda Bowl), Women (Venice Cup) and Seniors (d’Orsi Trophy).  One can compare the robot results to the human results as all the robot play records are shown and the links to the human records are given on the official website, www.computerbridge.com

Round 14 of the human round robin was used in the third round of the robot round robin. On board 12, 7♥ was the final contract at three of the six robot tables and 6♥ was the contract at the other three tables.

In one match Jack picked up 13 IMPs against Shark Bridge.

In another match Bridge Baron picked up 13 IMPs against Micro Bridge.

¹ 2NT or game force; ² 2 or 5 key cards; ³ no kings

In the other match WBridge5 picked up 13 IMPs against Q-Plus Bridge.

¹ game force; ² no ace, 7+ hcp; ³ 5 key cards

¹ 2NT or game force; ²control; ³0 or 3 key cards

In human competition 7♥ was reached 9 times in the Bermuda Bowl, 9 times in the Venice Cup (played once in 4♥), and 9 times in the d'Orsi Senior Trophy (played once in 5♥). So the robots' percentage was better (50% compared to 41%) than in the human’s, albeit with a small sample.

Board 15 of the same round produced a large swing on an opening lead against 6♦.

In one match, both Q-Plus Bridge and WBridge5 bid and made 6♦.

¹ one key card
opening lead, ♠ 8, making 6, N/S +1370

opening lead, ♣ A, making 6, N/S +1370

The other time 6♦ was bid.

¹ one key card, ² not the diamond queen.  N/S were on the same wavelength, that is, not stopping in 5♦.

opening lead, ♣ A, making 6, N/S +1370

At the other table Shark Bridge made +660 in 3NT. 12 IMPs to Jack

At the final match, the contracts were 3NT, +660 and 5♦, +620, with Bridge Baron picking up 1 IMP against Micro Bridge.

In the human championships, 6♦ was reached at many tables, and for the big clubbers with South as declarer after opening 1♦.  When South was declarer, West led a heart more often than not, but with North as declarer, the opposite was true.  The human play (except in Daily Bulletin articles) is not revealed, so the opening lead cannot be analyzed.  In 6♦ from the North side, the human defense got it right some times (25%), but the robots were 0 for 3.

In the final KO between Jack and WBridge5 there were many swing deals.

A slightly against the odds vulnerable slam by Jack produced a 13 IMP gain on Board 3 of the second quarter. Down one would have given WBridge5 13 IMPs and the crown.

Opening lead ♣5, making 6: E/W +680

¹2 of 5 key cards without trump queen; ² no kings

The probability of making 6♠ is approximately 44.25%.  62.25% of the 67.8% of the times trumps are 3-2 (whenever the ♣K is onside and approximately 12.5% of the times the ♣K is offside) plus 12.5% of the 28.3% of the times trumps are 4-1.  A long match can be decided by one slightly against the odds 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.

For the complete results go to www.computerbridge.com  You will find the 17 year history of the event, along with many publications and descriptions of computer play.  This year’s results also offer an opportunity to compare robot play against human play, with two sets of 16 boards to compare.  The complete robot play of the two sets are shown.  The complete play of the final KO is also shown along with some highlights.