6th World Chess Software Championship

Jan Krabbenbos, Jaap van den Herik

The 6th World Chess Software Championship started on July 2, 2016. Seven programs participated in a round robin tournament of seven rounds. The tournament took place at the Leiden University and is organized by the ICGA, LIACS and LCDS. The sponsors are Google, Naturalis Biodiversity Center, the municipality of Leiden, Leiden University, Faculty of Science, ICGA, iSSC, SurfSara, Digital Game Technology and NWO Exact Sciences. It is held in conjunction with the 22nd World Computer Chess Championship, 19th Computer Olympiad and the 9th Computers and Games conference.

Round 1

Ginkgo Raptor 0-1

Komodo Hiarcs -

Shredder Jonny -

Ginkgo versus Raptor proved that computers know many things and can compute even more. The opponents played a Semi Slav opening in which black castled to the queenside and the center was dominated by dynamic pieces and pawns. Both programs knew that there were many examples of previous games stored in their libraries. At move 22 white played a new move 22. Nb5. Earlier two other moves were played 22. Ne4 and 22. Na4. Apparently the attacked knight is a problem to white. This observation was very well exploited by Raptor. On move 28 (see diagram) it played Rd7-b7 and hit with this move the nail on its top: where should the white knight go and what should be the result? It turned out that there was no better place then Na7 and after 29. Qb6 the queens were exchanged. However whites knight problem was not solved and it took him several moves to free the knight. Black spend that time quite well and build up a won position. Although white had the pair of bishops against two knights, it turned out that the two passed pawns supported by the knight was sufficient for the win. On move 47 white agreed with this opinion by sacrificing the exchange in an attempt to prolong the game. Raptor completed the work efficiently and effectively.

The new world champion Komodo had a tough game against Hiarcs in the first round of the WCSC. After an English opening we saw that whites position had to stand some pressure by the black pieces. By the move 18. Bf5 black made an attempt to maximize his pressure with a variety of small threats. It was time for white to take appropriate actions. Komodo did so by playing 19. Bg2-e4 (see diagram). Surprisingly this move indeed solved all problems white was facing. After some large sequence of exchanging pieces the position was equal. Although both sides tried to prove that their side was slightly better it was in vain, the draw could not be avoided.

The game Shredder Jonny was a fantastic fight. After a declined Queens Gambit white tried to consolidate a small opening advantage. But Jonny aimed also on advantage and we saw a big fight on a squared millimeter. It looked that black was the more clever collector of small advantages. Jonny obtained some pressure on the white position. However Shredder understood the possibilities of the position quite well and succeeded time and again to reply adequately on the small threats post by Jonny. The diagram position is a telling example. Whites last move has been f3-f4 and now there was a large sequence of moves of which the outcome was a position with limited pieces and clearly drawish. However these players are both fighters up to the very end. For those who like to see the game to its full extend they have to replay some forty more moves in which the value of the game did not change. The draw was deserved result for both sides.

Round 2

Hiarcs Shredder 0-1

Raptor Komodo 0-1

The Baron Ginkgo 0-1

The second round of the WCSC was remarkable since all three games ended in a win for black. The first one was between Hiarcs and Shredder. They started with a sharp variation of the Sicilian Defense in which both sides had pawn run on opponent king. Mostly the issue is who is the first to bring the opponent king into danger. This game was an exception because both players seemed to be the first. The diagrammed position is a telling example of what was at stake. Black and white pawns intermingle in the front of the white and black king respectively. It was hard to get a correct evaluative answer although the expert opinion maybe a little bit inclined towards black since in retrospect we know that black is the winner of the game. Seen from the diagram position we believe that the outcome will be a win for one of the two. However this opinion disregards the defending power that current programs possess. They have ingenuity and find time and again escapes. That also happens in this game where white was able to reach an endgame of rook and bishop versus a queen with three pawns at both sides. Black played that position very well and won deservedly.

The game Raptor Komodo can be characterized as weaker player against the world champion. This is a well known feature in the human chess world. World champion Karpov was a chess player pur sang. He did not like analysis he liked to play. If he discussed a game afterwards and his opponent stated that the current position was objectively seen a draw he always invited the player with the words OK, you think so, but let us play and see what happens. This is the best characterization of the game Raptor Komodo. In early midgame Raptor lost now and then a tempo which Komodo exploited to its advantage. However the advantage so gained was not sufficient for a winning position. After a long fight in which Komodo had not reached his aims there was an unequal ending on the board. However equal or not Komodo played on and outplayed Raptor as did Karpov with many opponents. See the diagram position in which the endurance of play is materialized by winning the a-pawn. The conclusion is unavoidable the strongest program has won this match. It was Komodo.

In the game The Baron Ginkgo the white player started ambitiously and obtained a passed pawn on d6. Was it an asset or was it a liability? If it was a liability could it be made an asset? White worked very hard on answering this question positively. It sacrificed a pawn on f5 and really obtained a nice looking position. Now the question was how to exploit this position. On move 23 there was a decisive moment. White chose for the 23. Rd3. However better would have been 23. b4 or 23. a3 with the goal to answer 23. a5 with 24. b4. By missing this opportunity black was able to take the initiative in the complex position and slowly achieved the upper hand. That resulted in a deserved win for black.

Round 3

Komodo The Baron 1-0

Shredder - Raptor 1-0

Jonny Hiarcs 0-1

In the game Komodo The Baron we saw an English four knights opening. This opening always requires subtle treatment. Both sides are more or less at liberty to place their pieces on the appropriate squares. The best strategists have best winning chances. In the game Komodo showed its power. Nevertheless The Baron developed some nice ideas and handled accordingly. It looked that nothing was wrong with his approach although his pieces were not fully harmoniously placed. However next to strategy tactic plays an important role in chess. In the diagram position Komodo found a surprising move, worth to be played by the world champion. Komodo played 28. Rg1xg6. It fully destroys the black position. In the sequel black could have defended better, e.g., by playing 29. Bxf5 instead of 29. Rxf5 but this should not have changed the outcome. A deserved win by white.

Shredder Raptor was an exciting game that started as a Slav defense, Dutch variation. Shredder played rather active from the opening and it looked that he had a clear initiative in his hands. However black found a very good defense line which was based on the activity of its a-pawn. By his sharp play black challenged Shredder to go over to immediate action. The two different approaches are seen in the diagrammed position: black has a dangerous pawn on a2 and white has chances along the h-file. The question now is who is first and what is more important, to catch the black king or to promote the black pawn to a black queen. White played very accurately and started in the diagram position 28. Rh2. Black managed to prevent white from mating him but had to restructure its defending position. Still he had his asset on a2. White was well aware this pain in the ass and regrouped its pieces to eliminate the a-pawn. White did so in a very elegant way. On move 45 he simply took the pawn by his rook although its queen was attacked by black. The implicit change of queens ended the black chances completely. White won by following the better concept during the game.

In the WCSC Jonny Hiarcs is a game which is played under different circumstances than in the WCCC. Jonny is handicapped by 2396 cores. With only 4 cores it is still a strong program as can be seen in this game although Jonny lost. The game started as Queens Gambit Declined. Black played fiercefully but Jonny showed its experience and hold its own. Yet the initiative was with black. On move 25 Jonny took the wrong decision (see diagram), it played 25. b4? The idea was based on the cunning move 27. Rb1 of which the program much more than the reality could give him. In the diagram a better change would have been 25. Nxc6. The game progressed with black increasing its threats and opportunities. On move 37 there was no other opportunity for white than to sacrifice a pawn and hoping that the resultant ending would be defendable. It turned out not to be the case and so Hiarcs could add a nice victory on the former world champion to his credentials.

Round 4

Raptor Jonny 0-1

The Baron Shredder -

Ginkgo Komodo 0-1

In the game Raptor Jonny, Raptor did not show any respect for the former world champion. Righ