Arimaa/Distribution of Force

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Right next to the silver camel and far away from both silver dogs, the gold horses are poorly positioned. (Game)


To create effective threats, one must use pieces efficiently. A strong piece should not be wasted on a job a weaker piece could do. With no gold horse nearby, a silver dog is as secure on g3 as a silver horse would be, and thus the eastern silver horse can go west. Another basic concern is activity: strong pieces should be kept flexible and available for duty. The b2 gold horse is passive due to being blocked in. The a3 gold horse is less blocked, but still poorly placed; Gold's position would be stronger if he had a horse in the east to fight the silver dogs.

Pieces are often passive because they are blocked in at home, but even a functional advanced piece is passive if it is not doing anything useful. In a race, a piece is passive if it doesn't have time to do something.

Having the strongest local piece can be an asset. If a trap control fight pits two gold horses against a silver camel and dog, Silver might get full control of the trap, but Gold can't unless his elephant joins that fight. The strongest local piece can also help with goal attack, goal defense, mobility fights, etc.

AlignmentEdit

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With Gold's forces restricted, the silver dogs are strong attackers. (Game)

Alignment refers to the overall positioning of one army relative to the other, especially in regards to which piece faces which. A strong alignment will not, for example, waste an elephant on an enemy horse while the enemy camel is active elsewhere. Here, Silver's alignment is near-perfect: the silver elephant fights the gold camel, the silver camel fights both gold horses, and other silver pieces take advantage of the freedom this provides. The silver camel and c2 horse are both strongest local pieces, whereas Gold does not have a uniquely strong piece in any area.

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The silver elephant and camel ignored the gold horse.

Alignment may seem unimportant when a forced goal is in sight. However, a poor alignment could allow the opponent to get a quick goal attack of his own. In this endgame, Silver's apparently strong goal attack left the one remaining gold horse unopposed in the east. After 38g, Silver suddenly faced a goal threat which could only be stopped via an elephant sacrifice.

BalanceEdit

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Silver needs a dog in the west.

If too much strength is concentrated on one wing, the other may become vulnerable. A dog can be a strong attacker if there is no active enemy horse nearby, and stronger still if there is not even an enemy dog to counter it. Note that Gold currently has the uniquely strongest non-elephant piece in both the west and the east. Silver can move the e7 dog west, however, perhaps delaying a Gold takeover of c6 long enough for Silver to counterattack in the east. The silver elephant needed to face the gold horse, not the gold dog as it did in the actual game. There was not much point in having both silver dogs on the same wing as the gold horse. Even on a full board, it is usually not good for both dogs to face a single enemy horse; if there is an active enemy horse on each wing, it is probably best to split one's dogs, preparing for a strong attack on one wing and a strong defense on the other.

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The silver elephant is stuck defending a horse and dog, but the gold elephant is stuck defending goal. (Game)

Weak pieces should usually be balanced also, as a goal threat might negate an advantage elsewhere. Gold's hybrid frame–hostage–partial elephant blockade may appear strong, but it leaves Gold very weak in the west. The gold elephant is currently stuck defending goal, so the silver camel is free to disrupt the blockade. Using one's elephant to defend against rabbits is extremely inefficient.


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With a horse flip, Gold can unbalance Silver's forces.

Even on a full board, one wing might become quite weak. On 12g of this game, a horse flip unbalanced Silver's forces, allowing the gold dogs to become strong eastern attackers. A trap defender should watch out for such a flip, and watch out for a pull-and-replace which might set the stage for such a flip.

CentralisationEdit

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The gold camel cannot safely advance without the support of the gold elephant. (Game)

A centralized elephant affects all four traps. Here, the gold camel cannot defend f3 until the gold elephant comes east. If Gold played Me2n De1n Me3e De2n, Silver could push the gold camel to f4 (De3s ee4s Mf3n ee3e), where it would be doomed to capture in f6. This would not work for Silver if the gold elephant were in the center.

While attacking or defending a trap, an elephant should usually be on one of the more centralized key squares, e.g. c4 or d3 when next to c3. An exception might occur when there is a chance to threaten the enemy camel. However, an elephant should not automatically go after an enemy camel which is still in its own home territory.

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Gold pieces can move through the center. (Game)

Control of the center itself is also important, as pieces would often like to move through the center. The side with greater elephant mobility will tend to have better central control. In the diagram at left, Silver is limited by potential capture threats in c3 and f3. By contrast, Gold currently defends all four traps; the silver elephant's isolation allows the gold camel to defend c6, making the center safe for more Gold advances.

Even when neither elephant is marginalized, shared control of an away trap may improve one's central control; if the opponent owns only one trap, pieces in the center are safer. It is sometimes even possible to blockade the center.