Arimaa/Attacking/Techniques

From Wikibooks, open books for an open world
Jump to navigation Jump to search

With camels on opposite wings and forces otherwise balanced, each side will likely advance on its camel wing, trying to remove the defending horse from its key square. This is known as an EMH or elephant-camel-horse attack. Later in the game, similar attacks may use different pieces.

In an EMH attack, the elephant will usually advance first, and the horse second. So as not to be taken hostage, the camel will usually advance behind other pieces. Having one's camel held hostage may not be a problem, however, if holding it would leave the opponent poorly positioned for a counterattack.

Course of an EMH attack[edit]

Prelude: horse to a6[edit]

a b c d e f g h
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg 8
7 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg Arimaa cs.svg Arimaa rs.svg Arimaa rs.svg 7
6 Arimaa hg.svg Arimaa hs.svg Arimaa ds.svg Arimaa ms.svg 6
5 Arimaa eg.svg Arimaa hs.svg 5
4 Arimaa es.svg 4
3 Arimaa mg.svg Arimaa hg.svg Arimaa rg.svg 3
2 Arimaa rg.svg Arimaa cg.svg Arimaa dg.svg Arimaa dg.svg Arimaa cg.svg Arimaa rg.svg 2
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg 1
a b c d e f g h

game

When facing a strong opponent, there is no quick way to get one's horse onto a decentralized key square of a defended enemy trap. Silver can block c7 with a phalanx, and a defending silver horse can hold b6. Often, an attacking gold horse will go to a6, hoping to later get onto b6.

Likewise, an attacking silver horse may go to h3 in hopes of later getting onto g3. Anticipating such a counterattack, Gold blockaded h3 with rabbits; the silver horse can still get to h3, but must first move the h3 rabbit to h5 or g4, which would currently take five steps. Aiming to get a gold horse to b6 before a silver horse can get to g3, Gold is not worried about rabbit pulls, which would cost Silver time.

Occupy key square[edit]

a b c d e f g h
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg 8
7 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg Arimaa ds.svg Arimaa cs.svg Arimaa rs.svg 7
6 Arimaa hg.svg Arimaa eg.svg Arimaa ms.svg Arimaa rg.svg 6
5 Arimaa rg.svg Arimaa hs.svg Arimaa es.svg Arimaa hs.svg 5
4 Arimaa mg.svg 4
3 Arimaa rg.svg Arimaa dg.svg Arimaa dg.svg Arimaa hg.svg 3
2 Arimaa cg.svg Arimaa rg.svg Arimaa rg.svg 2
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg Arimaa cg.svg 1
a b c d e f g h

game

In this diagram, Gold has just played the pull-and-replace Mb4ns hb6s Ha6e, getting his horse onto b6. Note that the a5 rabbit allowed the camel to return from b5 even with the silver elephant on c5. It is common for a weak piece to advance on the a-file, and for weak pieces to occupy c3 and two adjacent squares, to give the gold camel greater mobility with the silver elephant nearby.

The gold camel now threatens to pull the silver horse south and take it hostage, giving Gold strong threats in both western traps, which Silver must not allow. In the game, the silver horse retreated to a6, from where it might get back onto b6 with a pull-and-replace.

The silver elephant will sometimes occupy b5 to block the gold camel, if the c6 trap doesn't need the silver elephant as a direct defender. Gold could still continue the attack, but might do better to move his camel east and create a second threat.

See #Maneuvers for more examples of ways to get a key square.

Rotate out elephant[edit]

a b c d e f g h
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg 8
7 Arimaa cs.svg Arimaa hg.svg 7
6 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa rs.svg 6
5 Arimaa ds.svg Arimaa mg.svg Arimaa hs.svg 5
4 Arimaa hs.svg Arimaa rs.svg Arimaa eg.svg Arimaa ds.svg 4
3 Arimaa hg.svg Arimaa ms.svg Arimaa es.svg Arimaa dg.svg Arimaa rg.svg 3
2 Arimaa rg.svg Arimaa rg.svg Arimaa cg.svg Arimaa dg.svg Arimaa cg.svg Arimaa rg.svg Arimaa rg.svg 2
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg 1
a b c d e f g h

game

Once one has achieved shared control of an away trap, an ideal continuation is to replace the friendly elephant with a weaker piece. From this position, Silver played 11s De3e ed3e dd4s cf6e, using a dog to control c3 and freeing the silver elephant to deal with Gold's attack at f6. The gold elephant, by contrast, must stay by c3 to prevent material loss, so the elephant rotation gives Silver the strongest free piece for now. In other cases, the removal of the attacking elephant might also free the defending elephant, but the lasting shared control should still give the attacker an advantage.

The right piece to replace the elephant depends on the defenders in the vicinity. In this case, no gold horse was near d3, so a silver dog could do the job. The presence of the gold dog on d2 might have allowed Gold to reclaim d3 with a pull-and-replace (12g Ec4ew dd3n Dd2n), but here it fails to 12s ee3n Dd3e dd4s dd5s, after which the silver dog on d4 blocks the pull-and-replace.

Alternative: switch wings with the camel[edit]

a b c d e f g h
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg 8
7 Arimaa ds.svg Arimaa cs.svg Arimaa cs.svg Arimaa rs.svg Arimaa rs.svg 7
6 Arimaa rs.svg Arimaa ds.svg Arimaa eg.svg Arimaa hs.svg Arimaa hg.svg 6
5 Arimaa ms.svg Arimaa hs.svg Arimaa es.svg Arimaa rg.svg 5
4 Arimaa dg.svg Arimaa cg.svg 4
3 Arimaa hg.svg Arimaa dg.svg Arimaa mg.svg 3
2 Arimaa rg.svg Arimaa cg.svg Arimaa rg.svg Arimaa rg.svg 2
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg 1
a b c d e f g h

game

In this game, the gold camel helped the gold horse get onto g6, and the camel now hastens to the western wing to defend against Silver's threats there. Gold is ahead, but his position is not ideal, as he has no good way to free his elephant. Meanwhile, the silver blockade on g7 prevents the gold horse from penetrating further into Silver's camp. Without that blockade, Gold might have moved the horse to f7 and controlled g6 with his camel. Instead, Gold will have to find a slower way to use his trap control advantage.

Some noteworthy features of the position:

  • The g5 rabbit prevents Silver from regaining g6 with a pull and replace. This defensive pull and replace is a common idea, as is blocking it by occupying g5.
  • Silver must keep a piece on d6 to prevent Gold from flipping the f6 horse. If Gold could remove the silver horse from the northeast, the silver army would be unbalanced, and a gold dog could become a strong eastern attacker. Such a flip occurred on 12g in this game, giving Gold strong trap control.
  • If Gold has time to advance the h2 rabbit to h6, Silver will be cramped in the east.

Defences[edit]

Counterattack[edit]

While not strictly a defense, a counterattack is often the correct response to an EMH attack if the defender's camel is on the other wing. Such positions are extremely sharp, and a difference of a few steps can be crucial. In an opening with camels on opposite wings, it is typically an advantage to have greater development on one's camel wing. Also, if the elephants are on the same wing this tends to favour the side whose camel is not on that wing, since that camel is the strongest piece on its wing.

Bring the camel[edit]

a b c d e f g h
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa ds.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg 8
7 Arimaa rg.svg Arimaa rs.svg Arimaa cs.svg Arimaa ms.svg Arimaa cs.svg 7
6 Arimaa hg.svg Arimaa eg.svg Arimaa ds.svg Arimaa rs.svg Arimaa hs.svg 6
5 Arimaa cg.svg Arimaa hs.svg Arimaa dg.svg 5
4 Arimaa es.svg 4
3 Arimaa mg.svg Arimaa dg.svg Arimaa hg.svg 3
2 Arimaa rg.svg Arimaa rg.svg Arimaa cg.svg 2
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg 1
a b c d e f g h

Silver brings the camel (game)

When an attacking horse occupies a key square, one possibility is for the defending camel to move through the back ranks to take it hostage. In the early days of Arimaa, it was thought that this defence might render elephant–horse attacks unsound. It has turned out, however, that this is not a good first response to an attack if the camel is far away. The attacker might have time to get enough control to resist the camel; otherwise, the attacker can often gain time by retreating a little while preparing an attack on the other wing instead. Bringing strong defenders to deal with an attack is an important resource more generally; for example, in this game Gold won material using his camel, then moved it through the back ranks to blunt Silver's eastern attack, since it no longer had large targets in the west.

In some cases the attacker can gain time by flipping the defender's back rank rabbits into the path of the camel, since they cannot retreat and must instead advance to the (attacker's) sixth rank to get out of the way. It may also be appropriate to put the elephant on the seventh rank to block the camel directly.

Stuff the trap[edit]

The defender might blockade squares around the trap to deny the attacker room to maneuver. In addition, it can be valuable for either side to occupy the trap square itself. If one side occupies the trap, the other cannot move pieces through the trap, and the piece on the trap can move off to defend the trap whenever necessary. If one might be forced to quickly abandon the trap, but still wants to occupy it, the weakest piece possible should be used.

Rabbit blockade[edit]

a b c d e f g h
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa ds.svg Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg 8
7 Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg Arimaa cs.svg Arimaa rs.svg 7
6 Arimaa hs.svg Arimaa ms.svg Arimaa eg.svg Arimaa hs.svg Arimaa hg.svg 6
5 Arimaa es.svg Arimaa rg.svg Arimaa rg.svg 5
4 Arimaa dg.svg 4
3 Arimaa hg.svg Arimaa mg.svg 3
2 Arimaa rg.svg Arimaa cg.svg Arimaa dg.svg Arimaa cg.svg Arimaa rg.svg 2
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg 1
a b c d e f g h

Gold's own rabbits block his northeastern attack. (game)

In the game at right, Gold advanced a rabbit to h5 in order to make g5 mobile for his camel, which he intended to use for a pull-and-replace that would get the h6 gold horse onto g6. Silver foiled this plan by pulling another gold rabbit to g5. Since rabbits can't retreat, the g5 and h5 rabbits and thus also the h6 horse are stuck in place as long as the adjacent silver pieces stay put. While the gold elephant stays by the trap, Silver should leave these rabbits in place; framing one would break this blockade, which stops any Gold attack on the east wing. If the gold elephant leaves e6, the blockaded h6 horse may then be vulnerable to the silver camel, and of course the gold rabbits can be captured when Silver chooses.

A flank rabbit advance may aid an attack, but one should be careful not to let a second rabbit get pulled up if the two rabbits together might block the attack.

Horse-by-elephant hostage[edit]

An attacking gold horse might be taken hostage by the silver elephant. This is usually a bad long-term strategy, but it is still a way to slow an attack, and might possibly result in a horse frame. It may be best for an attacking horse to initially go to a7 rather than a6, so the defending elephant can't even think about going after it.

Maneuvers[edit]

Here are some ways for an attacker to get initial shared control of an enemy trap. There is no simple recipe for attacking: any of these maneuvers might be prevented by the defender, and the rest of the board must be considered before pieces are committed to a local fight. The following are simply some common tactics that both an attacker and defender should be aware of.

The positions are all from actual games (which are linked) except that they are transferred to the c6 area, swapping colours if necessary.

a b c d
8 Arimaa rs.svg Arimaa rs.svg
7 Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg
6 Arimaa hs.svg Arimaa eg.svg
5 Arimaa hg.svg

game

The horse dives through the trap: Hb5en cc7n Hc6n. This may be dangerous for Gold if the silver camel is at home; even if the camel can't immediately take the gold horse hostage, the silver elephant may block the horse from retreating while the silver camel comes west. To prevent such a dive, the defender can either use a c7 phalanx or stuff the trap.
a b c d e
8 Arimaa rs.svg
7 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa cs.svg Arimaa ds.svg
6 Arimaa rs.svg Arimaa hs.svg Arimaa hg.svg Arimaa eg.svg
5 Arimaa mg.svg Arimaa es.svg Arimaa dg.svg
4 Arimaa rg.svg

game

Gold to move defeats the c7 phalanx with Ed6e cd7s cc7e Hc6n. The gold piece on c5 is essential, since otherwise the horse would be lost when the elephant stepped away. Were Silver to move here, the gold horse could be framed, although there would then be a chance for a pull-and-replace to get the gold horse onto b6.
a b c d
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg
7 Arimaa hg.svg Arimaa rs.svg Arimaa ds.svg Arimaa eg.svg
6 Arimaa rg.svg Arimaa hs.svg
5 Arimaa es.svg

game

Silver has blockaded b7 against the advancing horse, but Gold defeats the blockade with Ed7s dc7e rb7e Ha7e.
a b c d
8 Arimaa rs.svg Arimaa rs.svg
7 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg
6 Arimaa hg.svg Arimaa hs.svg Arimaa eg.svg
5 Arimaa rg.svg Arimaa es.svg
4 Arimaa mg.svg

game

Pull and replace by the camel from b4 (Mb4ns hb6s Ha6e), with a follow-up threat of pulling the horse back to c3. The silver elephant often occupies b5 to prevent this. Such defensive play is usually combined with a counterattack on the other wing, since it will not hold indefinitely. Note that in this case Silver can answer by framing the gold horse. The frame will not hold for long, but it may be a good way for Silver to gain time, depending on the situation elsewhere.
a b c d
8 Arimaa rs.svg Arimaa rs.svg
7 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa rs.svg
6 Arimaa hg.svg Arimaa mg.svg Arimaa hs.svg
5 Arimaa rg.svg Arimaa rg.svg
4 Arimaa rg.svg Arimaa es.svg

game

The gold camel goes directly into b6 with the gold horse on a6. Gold plans either to retreat the camel and put the horse on b6, or to move the camel through the trap to c7 or d6. Beware double hostages and blockades: in the linked game, this maneuver (played on 22g) was a mistake, because Silver blockaded the trap square, while Gold's own rabbits prevented the gold camel from retreating.
a b c d
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg
7 Arimaa hg.svg Arimaa rs.svg Arimaa hs.svg
6 Arimaa hs.svg Arimaa mg.svg Arimaa ds.svg Arimaa eg.svg
5 Arimaa es.svg
4 Arimaa rg.svg Arimaa dg.svg

game

Gold just played Rb2nn db6e Mb5n. The a7 horse prevents the camel from being taken hostage. In the game Gold was subsequently able to push the silver horse down the a-file and take a strong hostage.
a b c d
8 Arimaa rs.svg Arimaa rs.svg
7 Arimaa rs.svg Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg
6 Arimaa hg.svg Arimaa hs.svg Arimaa eg.svg
5 Arimaa rg.svg Arimaa es.svg Arimaa dg.svg
4 Arimaa rg.svg Arimaa mg.svg

game

Silver has blocked the gold camel, but Gold plays a pull and replace through the trap with the d6 elephant. It is easy for Silver to prevent this by stuffing the trap, but the piece in the trap may be vulnerable to being flipped towards c3, especially if it is a cat or rabbit.
a b c d
8 Arimaa rs.svg Arimaa rs.svg
7 Arimaa rs.svg Arimaa ds.svg Arimaa rs.svg Arimaa cs.svg
6 Arimaa hg.svg Arimaa hs.svg
5 Arimaa eg.svg

game

Gold plays Ec5we hb6s Ha6e. This one is relatively hard to prevent directly, but Silver might be able to make it bad by bringing her camel closer with a threat to hostage the gold horse, since the gold elephant is not on d6 to block. A drawback is that it loses a little time since the elephant probably wants to move to d6 afterwards. Note that Gold could also prepare by moving the elephant to b5, but this is dubious if the silver elephant can reach c5, as the gold elephant would lose time returning to the centre.
a b c d
8 Arimaa rs.svg Arimaa rs.svg Arimaa rs.svg
7 Arimaa rs.svg Arimaa cs.svg Arimaa ds.svg
6 Arimaa hg.svg Arimaa hs.svg Arimaa mg.svg
5 Arimaa es.svg Arimaa eg.svg

game

The gold camel has just moved to c6, threatening to reach c7 or help the gold horse onto b6. If the silver elephant leaves b5, the silver horse might be pushed towards c3. Camel-in-trap can be played with the gold elephant on c5 or d6; the a6 horse makes a camel hostage unlikely. If the elephant is on c5, it is essential that the camel cannot be pulled back to d6 for a fork.
a b c d
8 Arimaa rs.svg Arimaa cs.svg
7 Arimaa rs.svg Arimaa rs.svg Arimaa hg.svg
6 Arimaa hs.svg Arimaa es.svg
5 Arimaa hs.svg Arimaa eg.svg
4 Arimaa rg.svg Arimaa hg.svg

game

From this position the gold elephant occupied b6, pushing the defending horse away; the c4 gold horse then took b6 in what amounted to a multi-turn push-and-replace. Moving the elephant to b6 is an unusual and interesting method, possible in this case only because a deadlock on the rest of the board left Silver unable to punish the elephant decentralisation.