Arimaa/Other Hostages

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Other than the elephants, any piece can potentially be taken hostage, and often the elephant is the only friendly piece which can feasibly protect it. The value of such a hostage depends largely on which side is left with the strongest free piece.

Horse-by-elephant hostages[edit]

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The horse hostage does not benefit Silver, since the gold camel is more free than the silver camel (from this game).

Not all hostage positions are effective. Even with camel hostages, the hostage-holder is often more stuck than the defender, since the hostage could become an attacker if freed. This gets worse if an elephant holds a horse hostage instead, as in this diagram. If the silver elephant left the northeast trap, the gold horse would likely help its elephant make captures, perhaps decimating Silver's eastern forces. Thus both elephants are basically stuck, but consider the overall position. Gold would gladly trade his horse for the silver camel, which if it came east might get forked between c3 and f3. The gold camel is more free to move around; if the silver elephant left the northeast, Gold could likely make progress there before Silver could threaten the gold camel, which could easily be defended in the west. The camels are the strongest free pieces, but Gold's camel is more free, thus the hostage does not give Silver an overall advantage. Ultimately, this is an issue of alignment; decentralizing one's elephant on account of an enemy horse is highly questionable.

For now, the gold elephant is better placed on e6 than on f5. If e6 and e7 were clear, the silver elephant could pull the gold horse onto e7 and then fork it between traps. That is a possible advantage of positioning a hostage-holder behind the trap.

In some cases, a horse-by-elephant hostage might be converted to a frame or passed off to the silver camel. If Silver were better positioned for that, it would be urgent for Gold to prevent a solid frame or horse-by-camel hostage, which could free the silver elephant while the gold elephant remained stuck defending the horse.

Gold can advance in the east, and perhaps replace his elephant with two weaker defenders. With the balance of free pieces, elephant rotation should be doable for Gold, and would make the gold elephant and camel quite powerful.

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This horse-by-elephant hostage makes the dogs the strongest free pieces.

A horse-by-elephant hostage may be effective on a depleted board. In this endgame, such a hostage tied up the three strongest remaining pieces. Up two-to-one in dogs, Silver can dominate the rest of the board.

Horse-by-camel hostages[edit]

The camel is usually the piece that should fight an enemy horse long-term. This may lead to a horse-by-camel hostage, which will ideally tie the opposing elephant to defense while the friendly elephant is free to roam. However, the "defending" elephant can often attack the hostage-holding camel, and thus turn the tables. If the hostage is defended by the enemy elephant, a hostage-holding camel will need friendly support. If a solid horse-by-camel hostage is feasible, it may be worth using considerable material on, since it can give one the only free elephant.


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These diagrams illustrate different horse-by-camel hostage configurations, with Gold holding such a hostage in the southwest. A gold piece is always on a4, to keep the gold camel mobile if it is pulled to b4. In the first diagram, note that the b2 cat allows capture of the hostage in case the silver elephant goes to b4. Also, Gold should leave d3 clear; if d3 were occupied by any gold piece, the silver elephant could then afford to move to b4, since the only one-turn capture would end with the gold camel on c4, where it would be threatened in c6. While Silver tries to undermine this hostage position, Gold might gain an advantage elsewhere.

Without a gold piece securely on a4, the hostage would be weak. With ec4we Mb3n ha3e, Silver could have her elephant on c4 and her horse on b3; if the gold camel were frozen on b4, Silver would have strong capture threats in c3, and could also flip the gold camel to c5 with a threat to capture it in c6. The a4 square is thus crucial to such a hostage position, and Gold does well to have a horse on that square, as a weaker piece could be pulled away more easily.

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In the second diagram, the hostage horse is on b2 rather than a3. This means that the silver horse can more directly join the trap control fight if the camel is dislodged. For instance, if the silver elephant moved to b4, it would then threaten to capture the camel due to false protection. On the other hand, Gold now has the option of pushing the horse to b1, which would make it even more difficult for Silver to free the hostage. If the silver elephant left, the horse could then be pulled back to b2.

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In the third diagram, the silver elephant has no easy way to approach the gold camel. As long as Gold can hold b3, the hostage is fairly secure. This can be the strongest type of horse hostage, provided there are enough pieces to maintain it.

In all of these cases, the side defending the hostage should consider bringing more pieces into the local fight. For instance, in the last example Silver would have a strong position if she could bring a horse to b3, dislodging the gold dog. In the first, the silver camel might attack the a4 horse, weakening the hostage pattern.

Cat and dog hostages[edit]

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In this game, Silver's position would be much stronger if her camel were free and a silver horse held the gold dog hostage.

A smaller piece may also make a valuable hostage, if its elephant is the only piece which can defend it. In this example, the silver camel holds a gold dog hostage next to c6. The silver elephant is free to pull gold pieces toward f6. The gold elephant can't defend both traps.

However, Silver's situation is less than ideal, for two reasons. First, the gold elephant could currently leave the c6 trap without losing the c8 dog on the next turn, since the silver cat would have to leave the trap square to allow for the capture. Second, the h5 gold rabbit will make it harder for the silver elephant to hostage the gold camel. Silver might have to capture the h5 rabbit before making any other threat in f6.

In general, the advantage of a small piece hostage over a horse hostage is twofold. First, the smaller piece can be held hostage by a horse, sparing both the friendly elephant and camel for other duty. Second, it is easier to frame a small piece than to frame a horse. In the diagrammed position, Silver would have a greater advantage if her camel were on g6 and horse on c7; the silver camel could defend the f6 trap, while the silver elephant either dragged a piece to capture or assisted in framing the hostage dog. As things stand, the silver elephant must instead prioritize eastern defense. Like a horse-by-elephant hostage, a dog-by-camel hostage is at best non-ideal while all strong pieces remain.