2011 World Computer Championship

The 2011 Computer Championship began on the 1st of March 2011:

• Official Tournament Rules and Information

For other events see Event Reports

Participants

Tournament participants with pre-tournament information & history.

• Rating = Arimaa.com Gameroom Rating
• W-L = Cumulative Win-Loss record in all previous Computer Championships
• # Trn = Number of previous years competing in Computer Championships
• 1st, 2nd, 3rd = Number of all-time 1st, 2nd and 3rd place finishes

Seed	Participant	Author	Country	Rating	W-L	# Trn	1st	2nd	3rd
1	Marwin	Mattias Hultgren	Sweden	2134	8-2	1	1
2	Sharp	David Wu	United States	2101	8-9	3		1
3	Briareus	Ricardo Barreira	Portugal	1938		0
4	Bomb	David Fotland	United States	1862	31-9	7	5
5	OpFor	Brian Haskin	United States	1873	9-9	3			3
6	Clueless	Jeff Bacher	Canada	2056	26-14	6	1	3	1

Round 1

clueless vs. marwin 0-1

Clueless grabbed the early material lead on with a cat capture on 9g but then got into positional difficulty when a gold horse ran up the d-file and eventually became a hostage of the silver camel at c8 on the 15th turn. With a gold elephant, camel and horse tied up in the northwest quadrant, marwin was able to snatch a rabbit on 22s and a cat on 28s relatively easily. The gold horse escaped the hostage situation on 30s when the silver camel raced down the board to participate in a powerful goal attack rather than return to c7. A gold horse was lost on 32s and the silver goal threat still loomed in addition to the large material advantage. The gold elephant was forced back to the f2 square on 37g to halt the silver goal threat but even this huge concession didn't hold back the tide for long: a swarm of silver pieces overwhelmed the defending gold elephant and marwin appeared to be on the brink of victory when clueless ran out of time on the 43rd turn.

OpFor vs. sharp 0-1

Sharp obtained an eastern horse frame on move 8s but then abandoned it for an even stronger horse frame (one that didn't include its camel) on the western side on 12s. During the 17th turn the gold horse escaped from the frame just as Silver began an Elephant + Horse attack against the c3 trap while also capturing a gold rabbit in the northeast. Gold's best attempt to claw back towards equality on 19g likely would have been to get the camel out of its boxed-in position (though not a trivial task with an a3 gold rabbit and c4 silver elephant enclosing it) and so as to increase its mobility but instead, it moved to a5 and the silver elephant was able to freeze both the camel and a horse from the b5 square on 19s. That temporarily forced the gold elephant back to the northwest, conceding strong silver attacks against both southern traps. OpFor returned its elephant back to the home region to fight for control of at least one home trap and won a silver camel for a gold horse + rabbit. Silver had a slight lead after 26 turns but the position remained very tense and unpredictable. Sharp used a mobility advantage to gain the upper hand in the next sequence: with the gold elephant holding a hostage from the c2 square and the gold camel alone in the west, a silver horse threatened a gold dog in the northeast and captured it on 34s in return for a rabbit. Silver now had a horse + dog + rabbit in return for the camel while OpFor had a somewhat strong a6 rabbit to compensate slightly for the material disadvantage. But sharp continued to build an even stronger position and once the silver elephant was able to rotate away from the c3 trap on 36s, leaving the gold elephant in a passive position on c2. Active pieces on both wings, two advanced rabbits and strong trap control put too much pressure on Gold's defenses and a silver rabbit scored a goal on 46s.

briareus vs. Bomb 1-0

Diagram 1: briareus vs. Bomb

43s ra6ss Hb2s eb3s Gold to move with Silver possessing a scary western goal threat

Briareus got into significant positional difficulty in the opening as it allowed an Elephant + double-horse attack against the f3 trap while the gold camel stood passively on the e1 square. The gold camel joined the action on 16g and then was immediately frozen at d5 on 16s. Briareus threw rabbits into the north to help the camel stay alive longer and during the ensuing tactical battle Gold was able to salvage 2 silver dog captures in return for the lost camel and a rabbit. There was a rabbit trade on moves 28s and 29g to maintain Silver's slight material advantage. The gold elephant continued to have difficulties managing against a swarm of silver pieces around the f3 trap and by the 33rd turn Bomb appeared to have the stronger and more organized position. However, Briareus outplayed Bomb tactically during turns 38-41 with the aid of a diversionary dog and rabbit in the northwest, winning a silver horse, cat and rabbit in return for a gold dog and 2 rabbits. Silver maintained a positional edge after that mass exchange by fighting for shared control of both southern traps and advancing a very scary rabbit to a4 on 43s (Diagram 1). But Bomb played poorly after that, wasting its 45th move to flip a gold rabbit into a better long-term scoring location and then using its 46th move to needlessly sacrifice a d6 rabbit. Another silver rabbit was captured on 51g and it was clear that Gold now dominated both the position and the material count. Briareus found a pretty forced goal-in-two on 56g by using a passed silver rabbit to help blockade the silver elephant on the b6 square.

Round 2

marwin vs. briareus 1-0

Briareus advanced a rabbit from a7 to c6 on the 3s move and Marwin quickly jumped on the unfortunate rabbit, framing it at c3 on 7g. A two-for-two piece trade followed, leaving Gold ahead by a cat after 15 turns. Each bot used various tactical attempts to capture pieces or create goal threats and marwin won that particular battle by capturing a rabbit on 23g and then advancing a rabbit to c7 two turns later. A silver cat was sacrificed on 25s in a desperate bid to slow down the gold goal attack and allow enough time to switch the focus to the southeast. However, the silver goal attacks were too slow relative to the many gaps available for gold rabbit charges in the lightly-defended northwest. A dog was sacrificed on 31s to further delay a gold goal attack but this left briareus hopelessly behind in material. The silver forces were repeatedly decimated by one capture after another until finally, on the 42nd turn, there were no silver rabbits remaining on the board, giving Gold the immediate victory.

sharp vs. Bomb 1-0

This game almost resembled a human versus machine game where the Gold side exploited Silver's lack of positional understanding. Sharp commenced an Elephant + Horse attack against the f6 trap on move 3g and for the rest of the game that horse would remain a powerful attacker. The gold camel seized the b6 square on 7g and it would also remain a powerful force around that trap for the remainder of the game. On 12g a 2nd gold horse attacked the f6 trap and the rout was on: both of silver's home traps were under seige and an advanced gold rabbit on each side of the board put additional pressure on the silver defenders. Faced with the loss of a horse on the 16th turn, Bomb used its elephant to take one of the attacking gold horses hostage but the gold elephant was able to both capture the silver horse and defend the f6 trap without any difficulty. A long positional battle ensued in which Sharp used its western forces to gain full control of c6 while Bomb used its elephant to fight off the horses around the northeast trap. Rather than defend endagnered pieces around the f6 trap on 34g, Sharp instead offered a large exchange of pieces in which it could have won both the silver camel and horse and also obtain a strong goal attack. Bomb declined a capture on 34s in order to minimize its losses on the west side, however that soon left Gold in control of both sides of the board again. By the 38th turn Sharp had won a camel and two rabbits and still had powerful forces on each side of the board. Another silver rabbit was taken in f6 and then an eastern gold threat drew the silver elephant from c7 to d7 on 41s, opening the door for a new goal attack up the c-file. Finally, the gold camel rotated to b7 where it created a 3rd gold threat and this time it succeeded on move 44g.

OpFor vs. clueless 0-1

Diagram 2: OpFor vs. clueless

After 32g Dg3w rh3w Df3s rg3w rf3x Silver to move: Gold has just eliminated one rabbit but Silver finds a forced goal-in-three with the another.

Clueless gained the upper hand after an unusual 4g that left both the g3 square open to counter-attack and the b3 camel vulnerable to an elephant pull. Clueless used its 4s move to pursue the camel and it was flipped up to b5 on 6s before gaining an opportunity to escape on the 10th turn. Instead, OpFor went in for an attack against the f6 trap on 10g, a plan which had some promise until Gold got too amitious and advanced a cat all the way to d6 on 12g. The cat was lost on the 15th move because the gold elephant could not assist the cat's escape to d6 without exposing it to a “false protection” capture on silver's next move. Once again a gold piece got framed on the c6 square on 18s, this time a rabbit, but OpFor was able to keep it alive for the time being by blockading the d5 square. Another blockade was built on d4 to protect the c3 trap on 20g and yet another at e5 on 22g to protect a framed cat after the gold elephant pulled the silver camel to e6, possibly to prevent it from rotating to d5 at a later time. With many gold pieces tied up in the north or participating in blockading squares, clueless initiated a rabbit charge down the a-file on 22s where Gold was weakest. This led to the direct loss of the framed gold rabbit because the gold horse had to retreat to c4 to slow down Silver's powerful attack. Clueless ramped up the pressure with an eastern rabbit advance on 26s and soon the gold defence was relying on only rabbits on both wings to contain silver goal attacks. A silver dog was poised to dislodge the b2 gold rabbit defender on 29s, forcing Gold to abandon yet another framed rabbit, this time on its home trap. OpFor temporarily bottled up the western rabbit and had enough time to capture the eastern rabbit on 32g to narrow its material deficit to 2 pieces (Diagram 2). However, Clueless discovered a beautiful forced goal-in-three on 32s and the silver rabbit reached the d1 square on the 34th turn.

Round 3

sharp vs. marwin 0-1

Diagram 3: sharp vs. marwin

After 29g Rg3n Hg6e Rg5nn Silver to move: Gold has just weakened the southeast quadrant with a needless rabbit advance.

Sharp got into a world of trouble in the opening when its camel got stuck at e8 in the vicinty of the silver elephant. A silver cat was captured on 10g but that was the last material lead that Gold would have in the game. In a successful, but excessively costly bid to keep the camel alive, Sharp gave up a dog and rabbit and decentralized the gold elephant on 14g. With the two strongest gold pieces far away in the north, Marwin launched a counter-strike against the southwest quadrant. That plan quickly reaped a gold rabbit on 17s followed by a powerful rabbit advance on the east side on 18s to further strain the gold position. The gold elephant re-emerged into the middle on 20g but then was quickly pinned to the c5 square due to a horse frame on 21s. Despite all of its difficulties, marwin actually managed to advance a rabbit to f5 on 22g with some vague long-term goal possibilities. Before the gold rabbit could cause any problems, Marwin attempted to advance its own eastern rabbit with the help of a horse against 5 small gold pieces. The silver horse couldn't single-handedly fight off the swarm and the silver rabbit could not obtain the finishing goal strike. In fact, Sharp even removed one of the defending goal rabbits from the southeast quadrant (leaving 4 gold pieces to fight against the horse & rabbit) in order to intensify its own northeastern goal attack. Then on 29g another gold rabbit voluntarily advanced from g3 to g4 but this turned out to be a major long-term error (Diagram 3). By reducing the number of gold defenders in the southeast, Marwin found that it could bring in its elephant with decisive effect on 34s while the extra gold rabbits that wandered into the north played little role in the remainder of the game. Before Gold could build any steam in the northern goal attack Marwin used its pieces to freeze the 3 gold defenders, allowing the silver rabbit to finally advance down the h-file.

clueless vs. Briareus 1-0

The opening phase was a bit stodgy yet slowly but surely Clueless gained the advantage as weaknesses appeared in the silver position. On 16g Gold had the chance to take a clear positional advantage with a horse advance to g6 but it settled for a rabbit pull instead. In fact, it was Briareus that registered the first Elephant + Horse attack with the pulled rabbit acting as an asset at the h3 square. But the gold camel was relentless in pursuit of the attacking silver horse and Clueless regained a clear advantage on 28g thanks to a strong attack of its own against the f6 trap. The first capture was made on 30g when a gold horse removed a silver rabbit and things quickly went downhill for Briareus after the silver elephant pushed a gold rabbit into the weakened northeast on 30s. Silver had to devote the 32s move to a goal defence which allowed a silver dog to be captured on 33g. Briareus used delaying tactics to slow down the gold attack, but Clueless continually reversed the move while slowly building a second attack on the west side. When Silver used a full move on the 36th turn to reinforce the west, Gold won a third silver piece on 37g and then a fourth on the next move. The result was not in doubt yet Silver held on for 13 more turns before Clueless achieved its victory on 50g.

Bomb vs. OpFor 1-0

A silver cat onto the c5 square on 8s and it was flipped down to d4 on 9g. It should have easily escaped on 9s but OpFor inexplicably allowed it to remain in the middle of the board, even wasting a step to vacate the g6 square. The silver camel created a diversion on 10s to save the cat's life but once the two strongest silver pieces were occupied in the southwest corner it allowed Bomb to rapidly build an attack against the f6 trap. The gold camel roamed the board by capturing two gold cats and then freezing the silver horse at d2 on 17g. The horse was pushed into the f3 trap on 20g and Gold's lead was already apparently insurmountable. Adding to Silver's headaches were a gold rabbit that advanced to d7 on 26g followed by a dog frame on 27g. Several more piece captures followed before Bomb neatly forced goal-in-one on 38g by blocking out the silver defenders from the a-file. With the defeat OpFor is the first bot eliminated from the tournament.

Round 4

Bomb vs. clueless 0-1

Diagram 4: Bomb vs. clueless

After 25s dd6s me6sse Gold to move and increase the material lead

Bomb didn't accomplish anything concrete in the opening moves but Clueless did succeed in pushing the western gold horse north into the waiting arms of the silver camel on 12s. However, a silver horse was left vulnerable at the d5 square and that allowed Gold to trade his hostage horse away and maintain the material balance. As the game progressed Bomb started to build a huge positional advantage. The silver elephant and camel stood on the western half of the board but only the elephant was used to work on a cat frame. Meanwhile, the gold horse and camel were very active on the eastern half of the board causing much discomfort to the Silver pieces. A silver rabbit on 23g and then a silver horse was taken hostage at h3 two turns later. With the silver elephant far out of the action the silver camel was forced to defend the hostage horse from the f4 square (Diagram 4). Bomb calculated that it could abandon the c6 cat to chase the exposed camel, and the powerful silver piece was pushed into the trap on move 28g. At this stage of the game Gold was far ahead with an extra camel + rabbit in return for just a cat plus the gold camel stood near the silver horse, providing a further advantage. And yet Bomb failed to fully capitalize on the advantage by shifting its horse to the west when the opportunity arose. That simple adjustment would have given Gold a strong advantage of both wings rather than just the east.

Diagram 5 Bomb vs. clueless

After 53g Rc2ennn Silver to move and defend against the goal threat

Another silver rabbit was captured on 39g leaving Gold ahead by two extra pieces, including the camel which was powerfully positioned. Yet another silver rabbit fell on 43g but by this time Silver was starting to gain a strong eastern position to offset some of the material shortfall. Clueless made a great tactical move on 44s to force the win of material in the east. After the large tradeoff of pieces, Silver had made a great comeback by the 49th turn being down only 2 rabbits in exchange for an extra cat. Importantly as well, all of the gold rabbits stood on the first 3 ranks while the silver rabbits were starting to encroach into the south. Clueless was practically forced to by abandon the g2 silver horse on 53s in order to nab stop the d5 gold rabbit (Diagram 5). For a forced move, however, this 53s was particularly strong: by liquidating both the gold horse and dog along the d-file, Silver was set up for a very strong counter-charge down the c-file. By the 56th turn the fast-advancing silver rabbits were already creating serious goal threats and putting tremendous pressure on the gold elephant to hold them back. Bomb wasted many tempii trying to win material while Clueless simply pressed its rabbits towards the south, keeping all its pieces alive in the process. Move 62s was the final crushing blow against the weakened gold defenders: the capture of the g3 gold rabbit was inevitable and there weren't enough defenders to hold the fort after that. A silver rabbit scored the goal on 64s to seal the incredible comeback by Silver, largely thanks to Bomb's tentative play contrasted against the aggressive rabbit attacks by Clueless.

Computer Championship Results

Seed	Participant	Rd. 1	Rd. 2	Rd. 3	Rd. 4	Rd. 5	Rd. 6	Rd. 7	Rd. 8	Rd. 9	Rd. 10	W-L	Finish
1	Marwin	S 6 W	G 3 W	S 2 W	Bye	G 6 W	G 2 L	Bye	S 2 W	G 2 L	S 2 L	5-3	2nd
2	Sharp	S 5 W	G 4 W	G 1 L	S 3 W	Bye	S 1 W	G 6 W	G 1 L	S 1 W	G 1 W	7-2	1st
3	Briareus	G 4 W	S 1 L	S 6 L	G 2 L							1-3	t-4th
4	Bomb	S 3 L	S 2 L	G 5 W	G 6 L							1-3	t-4th
5	OpFor	G 2 L	G 6 L	S 4 L								0-3	6th
6	Clueless	G 1 L	S 5 W	G 3 W	S 4 W	S 1 L	Bye	S 2 L				3-3	3rd