Arimaa/Distribution of Force

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Neither gold horse can fight either silver dog. (game)

An important element of Arimaa is the overall distribution of pieces. One basic concern is efficiency: a strong piece should not be wasted on a job a weaker piece could do. At right, Silver would gain no further advantage by having a horse on g3, so the silver dog is efficiently placed there. 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 creating or furthering a threat.

Having the strongest local piece is often crucial. 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.

The army which is better distributed overall will have the advantage.

Alignment[edit]

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Silver is dominating the entire board (game).

Alignment refers to the general positioning of the army relative to the opposing army. Strong pieces should not be wasted; a good alignment is one where the friendly elephant neutralizes the enemy camel, the friendly camel neutralizes at least one enemy horse, and the other pieces take advantage of the freedom this provides.

In the diagram, Silver has a large alignment advantage: the silver elephant fights the gold camel, the silver camel fights gold horses, and the c2 horse fights a gold dog. The silver camel and c2 horse are both strongest local pieces, whereas Gold does not have the strongest piece in any area.

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The silver elephant and camel ignored the gold horse, letting it create a strong goal threat.

A poor alignment can lose a nearly won game. In this endgame, Silver had a camel advantage, but still let the one remaining gold horse beat her. When it went north on 36g, Silver took no notice. With nothing to stop the gold horse in the northeast, it created a one-turn goal threat on 38g. At that point, Silver had only one way to stop it, and that left her elephant on the f3 trap square. The elephant was lost.

Balance[edit]

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Silver needs a dog on each wing.

It is usually best to have some strength on each wing. In the position at right, from this endgame, the strongest remaining pieces are the elephants, horse, and dogs. Gold has split his horse and dog; the dog has just advanced in the west, and the horse is poised to advance in the east. The silver elephant cannot fight both at once, but would do best to confront the horse, which could otherwise dominate the east. Silver would however be left vulnerable in the northwest if the silver elephant went east.

Having both silver dogs in the east is pointless; a second dog is not needed to defend f6, and doesn't improve Silver's prospects for taking over f3. The e7 dog should move west, to counter the gold dog and delay any Gold takeover of c6. In the actual game, Silver left both dogs in the east, and soon got into trouble. Had Silver balanced his dogs, he would have had time to counterattack in the east.

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In this game, the silver elephant is stuck defending a horse and dog, but the gold elephant is stuck defending goal.

It is also often important to balance weak pieces, which are vital to home defense and to goal threats. With three gold pieces already gone, and eleven gold pieces tied up in the hybrid frame–hostage–partial elephant blockade, Gold is very weak in the west. The gold elephant is currently stuck defending goal, so the silver camel is free to disrupt Gold's eastern position. Using one's elephant to defend against rabbits is extremely inefficient.

Centralisation[edit]

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

Ideally, an elephant should be able to quickly get anywhere it might be needed. Thus it should stay fairly centralized, until it has sufficient reason to go to the outskirts.

The diagram at right illustrates the tactical dangers of elephant decentralisation. The gold elephant has gone far away from f3, allowing Silver to start an attack there despite the gold camel's presence; until the gold elephant comes east, the gold camel cannot safely chase the g3 horse. 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 were the gold elephant in the centre.

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Gold pieces can move through the center. (Game)

Control of the center itself is also important; pieces which can't move through the center will have a harder time navigating the board. 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. Gold is freer in that regard, due to the respective positions of the elephants.

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.

Development[edit]

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In this game, Silver is better developed.

When one army is more advanced than the other, the more advanced army has more room to maneuver and gets the first chance to attack. The opponent must then divert resources to defense, perhaps allowing the advanced army to develop further.

In the diagram at right, each side is missing a rabbit, horse, and camel; with fewer pieces to threaten capture, advanced pieces are safer. Although material is even and neither side has a piece on the enemy's first two ranks, the middle four ranks contain twelve silver pieces but only eight gold pieces, giving Silver a space advantage. Of course, the need for development must be tempered by the need to defend one's home traps and goal line. If direct home defense is sparse, the advanced army must stop threats from getting that far. Here, Gold has a potential eastern goal which is currently blocked via congestion, although the g3 dog could flip away the g4 cat.

Advances are often risky in the opening, though it is usually good to have pieces advanced on a wing where one may get a strong attack—for instance on one's camel wing if camels are on opposite wings. In a slow opening, the attacking potential of advanced pieces may be outweighed by the risk of capture in away traps.

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Silver's advanced pieces stop Gold from advancing.

In this opening, Silver's advances were very effective. By 24g, Gold's options were severely limited; the gold elephant couldn't go east, lest the silver camel clear space for a goal.