Arimaa/risteall vs. ChrisB

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In this 2018 postal game, a horse pulled a rabbit and was then itself taken hostage. A solid horse-by-camel hostage is usually worth more than a rabbit, but this hostage position was too dependent on the elephant, and then fell apart when the elephant left.

Game

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Diagram 1: the setups.

  • 1g. An MH setup gives Gold possibilities of quickly attacking c6. On the other hand, it gives Silver the option of placing both horses far away from the gold camel.
  • 1s (diagram 1). Instead Silver also uses an MH setup, perhaps setting the stage for competing attacks. The silver camel is on the f- rather than g-file, however, and may go west to defend c6.
  • 2g Ha2nnnn. Gold immediately advances the a2 horse to a6, from where it might later take b6. There is no direct punishment for the horse advance, as 2s ee7swww 3g Ed2nnnn would give Gold a strong position.
  • 2s ee7sssw. Silver goes the more conventional route, advancing his elephant immediately. If the gold elephant wants to advance to d5 or d6, it must now step around the silver elephant.
  • 3g Hg2n Cg1n Mb2n Ed2n.
  • 3s hg7s mf7ws de8s. Both sides develop; Silver brings his camel one file closer to the a6 horse, threatening to hostage it. For such a hostage to be effective, the western silver horse might first have to advance to a5.
  • 4g Ha6s ra7s Ha5s ra6s. Unable to block the silver camel from b6, Gold retreats his horse and pulls a rabbit along. In pulling the rabbit, Gold is perhaps trying to justify his 2g, but may be compounding a mistake. The pulled rabbit may impede an attack on c6; Gold has limited himself on his camel wing, and has still not advanced his elephant beyond the third rank. This shows why a horse does not typically advance ahead of its elephant at the outset.
  • 4s ed4ww rf8s ra8s. Silver could aim for an attack on f3, but instead moves his elephant west, protecting his rabbit and threatening to flip the gold camel or horse toward c6.
  • 5g Dc2w Ed3nw Mb3e. Gold chooses the only move that will free his camel without exposing a rabbit.
  • 5s eb4s Ha4en eb3n. Silver flips the horse, intending to hostage it with his camel.
  • 6g Rc1n Ec4n ra5s Hb5w. Gold pushes the silver rabbit toward the c3 trap. If Gold instead pushed the rabbit back to a6, it would be difficult for Silver to take a horse hostage. However, Gold is willing to allow the hostage, believing that Silver cannot hold it without his elephant nearby. The a5 square will be crucial to a horse-by-camel hostage position, as the silver camel could be pulled from b6 to b5.
  • 6s eb4n me6www. This is the only move that will not allow Gold to separate his horse from the silver camel.
  • 7g Ra1n Db2n De2n Hg3n. With the silver camel now on the west wing, Gold begins to advance in the east. Gold also moves toward a partial blockade of the silver elephant, which is currently committed to securing a horse hostage.
  • 7s mb6we Ha5n de7s. Silver is perhaps too quick to move the gold horse to a6, as this further blocks in the western silver horse. This hostage will only be strong if the silver elephant can leave, which would require the silver camel to have support on the a-file.
  • 8g Rb1n Db3n Rb2n Mc3n. Gold blockades the silver elephant. Silver could unfreeze and advance his rabbit, but Gold could reestablish the blockade: 8s eb5w ra4s ea5e 9g Db4w Rb3n Rc2wn.
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Diagram 2: after 8s.

  • 8s cd8e dd7e cc7e hb7e (diagram 2). With no other escape path, Silver prepares to move his elephant through c6 without disturbing the horse-by-camel hostage.
  • 9g Rh2n Cd1n De3ww. Gold brings his eastern dog west, so that he can push the silver rabbit south and still maintain the b4 blockade. Gold's forces are becoming quite imbalanced, however, with strength increasingly concentrated in the west.
  • 9s mb6n eb5ne mb7s. The silver elephant escapes through c6.
  • 10g ra4s Db4w Rb3n Dc3w. Breaking the hostage immediately with 10g Ec5we mb6s Ha6e runs into 10s ec6e Hb6e ra7ss, after which the gold horse could again be threatened. Gold therefore threatens the rabbit.
  • 10s ec6ess de6w. By centralizing his elephant, Silver moves toward a second threat. If Gold now captured the rabbit, he could not save both horses.
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Diagram 3: variation from 11s. Silver has captured a horse, but cannot save his camel.

  • 11g Ec5we mb6s Ha6e. Gold breaks the hostage and threatens the silver camel, which he could capture if the silver elephant went east: 11s ed4ee Hg4n ef4e 12g Mc4se 12s Hg5w eg4n Hf5nx eg5w 13g Ec5e mb5es Ed5w (diagram 3).
  • 11s ra7s rb8ws ra6s. Unwilling to abandon his camel, Silver advances rabbits to unfreeze it and perhaps get it back to b6.
  • 12g Re1n Rh1n ra5n Da4n. Gold pushes the rabbit back so that the silver camel is again frozen.
  • 12s Mc4s ed4w de7s ce8s. Silver defends his advanced rabbit and prepares to unfreeze his camel from below.
  • 13g Db3s ra3e Ra2nn. To keep the silver camel frozen, Gold blockades b4, keeping his own camel on c3 so that it can go east. Alternatively 13g Rb4w Db3n ra3e Cd2n prevents Silver's next move.
  • 13s Mc3e ec4sn Rc2n. This move delays and complicates the rabbit frame, which may now require a gold rabbit on d3.

    An alternative approach was to block the gold camel from the east and try to advance there, using Gold's comparative weakness in the centre and east. 13s ec4es de6ss threatens to penetrate the gold lines with the dog, and the gold camel has trouble going east: if it moves to d4 it will be pushed to e5. Gold might be forced into messy tactics like 14g Mc3n rb3e Db2n Hg4w 14s hg6sss 15g Ec5n mb5ee Ec6s.

  • 14g Rf1w Cd2w Md3e Rc3e. The gold camel steps east so that it cannot be pushed back to c3. The Rf1w step anticipates the silver elephant coming to c2 and thus creating a western goal threat.

    Although the silver camel is frozen, it cannot be pushed south; advanced gold rabbits restrict Gold as well as Silver. Gold's rabbit advances have also left his goal line thinly defended against the silver rabbit on b3.

  • 14s ec4e Rb4es ed4w. If Silver now moved his elephant to c2, he would have threats in both c6 and c3, and a goal threat. 14s ec4s Cc2e ec3s de6s 15g Rb4e Rd3w Me3w Re1w 15s Db2s ec2w rb3ws 16g Rd1w Db1w Rc1w Cd2w 16s eb2nn Hb6n mb5n could work for Silver, although the details are unclear. Instead, Silver flips the b4 rabbit onto c3, clearing space to unfreeze his camel. This move appears to concede the advanced silver rabbit, which can now be framed, and will then disappear when the silver elephant steps west. Silver did not yet need to worry about his camel, which posed problems for Gold even while frozen.
  • 15g Rd3n Rc3e rb3e Db2n. The silver rabbit is finally framed, but a gold rabbit is exposed on d4.
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Diagram 4: after 15s.

  • 15s ec4w rc3x Hb6n mb5n eb4n (diagram 4). Silver might want to move his elephant back to c4 after moving his camel, but Gold could undo that move and still create a new position, as a silver rabbit would be gone: 15s ec4w rc3x Hb6n mb5n eb4e 16g Ec5we mb6s Hb7s would give Gold a winning repetition fight that would soon force Silver to play a move other than ec4w Hb6n mb5n eb4e. Silver could push the gold horse to c6, but that would allow it to escape east and strengthen Gold's position e.g. 15s ec4w rc3x Hb6e mb5n eb4e 16g dd6s Hc6e dd5e Hd6s 16s Rd4e ec4e Hd5n ed4n 17g Ec5n mb6s Ec6w. With no good way to return to c4, the silver elephant goes to b5, preparing to once again move through c6 if Gold blockades c4.

    Comparing diagram 4 to diagram 2, the gold horse has been moved from a6 to b7, which gives Silver the option of pushing it to b8, protecting the silver camel and clearing b6 for the silver horse. On the other hand, Gold is more advanced and has captured a rabbit; the rabbit capture gives Gold a freer position as well as a material lead.

  • 16g Ec5e Me3n Ed5w dd6s. Gold threatens a silver dog and also blockades d4. The dog could be flipped to c4 if the silver elephant immediately went north to escape through c6. The gold camel advance will complicate any retreat by the silver dog.
  • 16s eb5s Da5e ra6s de6w. Silver threatens to frame a dog and thus further restrict the gold elephant.
  • 17g Cc2nn ra5n Db5w. Gold occupies c4, further boxing in the silver elephant. By pushing the a5 rabbit back to a6, Gold avoids the dog frame and weakens Silver's hostage position; without a silver piece on a5 or b4, the silver camel could not return to b6 if pulled to b5. The elephant is the only silver piece which can safely occupy b4 at this point, so in order to free his elephant, Silver must occupy a5 or move the hostage.
  • 17s Hb7n mb6n eb4nn. The silver camel retreats to b7, pushing the gold horse to b8; this may soon lead to a horse hostage held behind the trap, where the silver camel will be safer. With the gold horse no longer able to take b6, Silver might get better control of that square, and perhaps not need to keep his elephant nearby. With the other two steps, Silver could move the c7 horse to b6; the gold cat would hang after 17s Hb7n mb6n hc7sw 18g dd5e Ec5e Me4s de5s, while Silver is just in time to defend the dog after 18g Me4nn dd5e Rd3w 18s Db3w eb4sse. In the latter case the gold camel might join the fight at c6 before the silver elephant returns to the centre, with a messy position which is probably good for Gold.

    Rather than moving his horse to b6, Silver moves his elephant to that square, preferring the northwest as an escape route. However, this hangs the d5 dog.

  • 18g dd5e Ec5e Me4s de5s. This capture-forcing move would not be effective were the gold horse still on b7, as the horse could then be captured in exchange for the dog.
  • 18s eb6se Da5e ra6s. Silver threatens a gold dog and advances a rabbit to prevent it from retreating.
  • 19g dd6e Ed5n de4e Me3n. The d6 dog is pushed east rather than west since this weakens the hostage trap.
  • 19s mb7s ec5ee Rd4n. The silver elephant moves east and pulls a rabbit, which will not have time to step west if Gold captures the dog and retreats both his camel and horse. The silver camel steps south to defend the c6 trap, leaving the gold horse unfrozen on b8. This horse is still boxed in, and thus remains hostaged in a strategic sense.

    The rabbit pull is a mistake, however, as Silver cannot afford to use two more turns on a rabbit capture. It would have been better to reestablish a one-turn threat to the hostaged horse, with 19s mb7s Hb8s ec5ee or 19s hc7sw mb7e Hb8s.

  • 20g Cc4n ra5n Db5w Rd3n. Gold could capture the f4 dog, but wants to push the a5 rabbit back to a6 while a6 is still empty; if silver rabbits held both a6 and a5, Silver's horse hostage would become stronger, as the silver camel could not be frozen on b5. Gold thus retakes a5 in a move that also takes c5 and clears b5. This may allow the gold elephant to push the silver camel south, perhaps creating a double-threat in the west.
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Diagram 5: Variation from 20s. Gold is up by a dog and rabbit, but does not have a quick plan.

  • 20s Me4s ee5s df4nw. Silver chooses to save the f4 dog, allowing Gold to proceed with the western camel push. Had Silver used his last step to move his camel to b7, he could have then lost the c7 horse. Had Silver conceded the dog, he could have preserved the horse hostage with 20s hc7s Cc5s hc6s cd7w 21g df4sx Hg4ws Me4s 21s ee5s Rd4s ee4w mb6n (diagram 5), leading to a position where neither side had a quick plan. While Silver would have been down by a dog and rabbit, he might have been better off strategically than he is now.
  • 21g Ed6w mb6s Ec6w Hb8s. By pushing the silver camel south, Gold separates it from his horse, threatens it in c3, and weakens Silver's defense of c6. The gold horse returns to b7, prepared to take b6 or c7.
  • 21s de6w Rd4w ee4w rc8w. Hoping to block the camel-capture threat in c3, Silver pushes a gold rabbit west. However, Gold can now take c7. 21s de6ww cd7s would have allowed the silver horse to hold c7.
  • 22g Eb6ew hc7s Hb7e. Gold could create a one-turn camel-capture threat with 22g Db3ee mb5s Eb6s, but after 22s Rc4s ed4w de5n, Gold himself faces a double-threat in the west, and does not have time to take a secure camel hostage. Silver would have further threats in c6 e.g. 23g Hb7s Re2ww 23s mb4ss Cc5n ec4n.

    Gold thus opts not to immediately threaten the silver camel, and instead gets his b7 horse onto c7 to strengthen his control of the c6 trap. However, the silver horse was not likely to stay on c7, and has now gotten a free step forward. Gold might have done better to move his camel and g4 horse east.

  • 22s ed4e Rc4e Cc5s hc6s. Now framed on c6, the silver horse could be captured if the d6 dog were dislodged. Silver could move a piece to d8 and thus blockade d7 against the c7 horse, but would rather free and further advance his horse, which could soon be part of a multi-piece defense of the hostaged silver camel. Silver could delay a standard camel hostage pattern with 22s de5n Rd5e Cc5e hc6s 23g Db3ee mb5s Eb6s 23s Rc4s ed4w Ra4s mb4w, although this leaves the elephant blocking the further advance of the horse. Later in the game the silver elephant went to d3; it was probably better to do so immediately with 22s ed4s Rc4e Cc5s hc6s.
  • 23g Db3ee mb5s Eb6s. Gold threatens the silver camel and ensures that his own camel will be active in the east if the silver elephant defends.
  • 23s Me3e ee4s rb8ss. Silver does not yet need to defend c3, as he now has a counterthreat to the gold camel. With the b-file rabbit advance, Silver prepares to unfreeze his western horse and perhaps attack c3; a false protection capture would now be possible if the c5 horse were active.
  • 24g Hg4ww Mf3n Re2w. Gold blockades e4, delaying any eastern threat by Silver. By placing his camel near a silver horse and his horse next to a silver dog, Gold strengthens his alignment. The rabbit on d2 prevents the d3 dog from being pushed back; the dog could only be pushed onto c3, which would blockade c4 and thus strengthen Gold's control of the trap.
  • 24s Dd3w ee3w dd6w cd7s. To save his camel, Silver does indeed push the dog west. He also blockades c5 and c6. However, a western gridlock would leave Gold strong in the east.
  • 25g mb4s Eb5s Re1n Rd2w. If Gold now pushed the camel twice and created a typical hostage position, his dog would still have to move off of c3 before the silver camel would face a one-turn threat. Gold thus pushes the camel only once, even though this momentarily leaves Silver strong around c3, which Gold defends by keeping his dog in the trap and moving a rabbit to c2. Silver might try to free his elephant with 25s ed3e Dc3e Cc4s hc5s, but this would leave the northwest vulnerable to a goal attack.

    Earlier in the game Gold's space advantage made it easier for Gold to fight against the horse hostage. It now strengthens the camel hostage by making it harder for Silver to advance towards c3, and giving Gold quicker threats at c6.

  • 25s ed3e Rd4s He4w ee3n. Seeing few viable moves, Silver offers a camel trade. After 26g Rh3nw Mf4s Rc2e, however, Gold's camel would be safe, and Silver would have to reverse his 25s to save his own camel.
  • 26g Rd3e Dc3e mb3ex Eb4s. But Gold will gladly take the camel trade, which will leave him strong in the west.
  • 26s Mf4n ee4e Mf5nx ef4n. Silver captures the gold camel. Silver could have tried 26s rb6s dc6w Mf4n ee4e, but then after 27g Hd4e de5n He4n Mf5e, Silver would come out well behind whether or not he captured the camel.
  • 27g Eb3nn Cc4w Re3n. Gold threatens a silver horse, moving his cat out of the way. With c4 now empty, Gold advances a rabbit to e4 so that the gold horse cannot be pushed to c4, where it would block the capture of the c5 horse.
  • 27s de5n Rd5e hc5e ef5s. The silver horse retreats and threatens a gold rabbit. The fourth step is a mistake, as b6 should have been blockaded. However, after 27s de5n Rd5e hc5e ra7e both the horse and the c6 trap remain vulnerable, for instance 28g Eb5ew hd5w Hd4n 28s hc5se Cb4e dc6s 29g Eb5s Cc4sw Eb4e 29s rb6ss cd6ww 30g Da5e cb6e Db5n Ra4n.

    The alternative was to attack in the east with 27s hg6sss ef5s. Then Gold would probably not want to capture the horse immediately, but would still win it after 28g hc5s Eb5e Dd3e. Gold would have to defend for a few moves, but should be able to do so comfortably.

  • 28g Eb5e Da5e rb6n Db5n. Gold's attack is crushing, as captures in c6 will come with very quick goal threats.
  • 28s hg6sss ce7w. The silver elephant could probably defend c6 in time to prevent a short-term goal, but Silver's position would be hopeless, as the gold elephant could rotate out and dominate the board. Silver thus counterattacks f3; Gold can win this race, but there is always a chance that one with a winning position will miscalculate. An apparently hopeless counterattack may thus be better than a hopeless defense.
  • 29g cd7e Hc7ew cd6n dc6x. Silver had no way to prevent this capture once the frame was in place.
  • 29s ef4sw Rf2nx cd7s. By capturing the f2 rabbit and moving his elephant to e3, Silver makes way for a goal threat on the f-file. To protect the d5 horse, Silver steps the d7 cat to d6; Gold will not have time to capture both the cat and horse.
  • 30g Db6e Ra4nen. Gold creates a one-turn goal threat, to stay ahead of any goal attack by Silver.
  • 30s cd6nnw ce7w. Silver uses congestion to delay the goal.
  • 31g cc8e Hc7n Dc6n. Gold ensures that Silver cannot block the western goal line.
  • 31s rf7sss ra6s.
  • 32g Dc7s rb7e Rb6nn. Gold wins.