Arimaa/Other Hostages

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

As with a camel hostage, a horse hostage will be effective only if it gives the hostage-holder an advantage in free pieces.

Horse-by-elephant hostages[edit]

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

This horse hostage does not benefit Silver, whose camel is very limited (from this game).

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. The camels are the strongest free pieces, but Gold's camel is more free, thus the hostage does not benefit Silver. 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 begin to advance in the east, but should try to avoid having a second piece taken hostage while the gold elephant is still needed for defense. The more Gold has at stake in the northeast, the more aggressive Silver can afford to be elsewhere.

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

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. If a second gold horse or dog remained, this hostage would likely be weak.

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 hostage-holder's 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.


5
4 Arimaa hg.svg Arimaa es.svg
3 Arimaa hs.svg Arimaa mg.svg
2 Arimaa rg.svg Arimaa cg.svg Arimaa rg.svg
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg
a b c d e

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 if the silver elephant goes to b4. Gold should leave d3 clear, so that the camel could finish on d3 after making that capture. The b2 cat and empty d3 square indirectly protect Gold on the b-file; if the silver elephant could afford to step west and begin the next turn on b4, things could quickly turn around. As things stand, this may be a solid hostage position for Gold, whose own elephant is the strongest free piece for the time being.

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.

5
4 Arimaa rg.svg Arimaa es.svg
3 Arimaa mg.svg
2 Arimaa rg.svg Arimaa hs.svg Arimaa cg.svg Arimaa dg.svg
1 Arimaa rg.svg Arimaa rg.svg Arimaa rg.svg
a b c d e

In the second diagram, the hostage horse is on b2 rather than a3; this has implications 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. If the silver elephant left, the horse could then be pulled back to b2.

5
4 Arimaa rg.svg
3 Arimaa dg.svg Arimaa es.svg
2 Arimaa rg.svg Arimaa mg.svg Arimaa cg.svg Arimaa dg.svg
1 Arimaa rg.svg Arimaa hs.svg Arimaa rg.svg
a b c d e

In the third diagram, the silver elephant cannot easily displace the gold camel. As long as Gold can hold b3, Silver could only break this hostage position by decentralizing her elephant. This can be the strongest type of horse hostage, provided there are enough pieces to support the camel while its elephant is active elsewhere.

In all of these cases, the side defending the hostage should consider bringing more pieces into the local fight. In the last example, Silver might 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.


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

Gold cannot save both horses. Game

While a horse-by-elephant hostage is usually a bad long-term strategy, it may be an effective tactic if the hostage-holder can make a quick second threat. Here, Silver took both gold horses hostage, and Gold did not have time to defend both traps.


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

The gold elephant is needed at home.

On 23s of this game, the silver camel took a gold horse hostage. The western silver dog and the silver rabbit behind it proved crucial, as they stopped Gold from retaking ownership of c3 and threatening multiple captures; the gold elephant then quickly returned north to defend the horse hostage, and Silver owned c3. Silver decimated Gold's forces around c3, all the while retaining the threat in c6. The gold elephant should have defended c3 and let the c8 horse be captured, as that capture would have only pulled Silver even in material.


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

Silver's horse-by-camel hostage allows silver dogs to control an away trap.

By tying up the gold elephant and horse, Silver's horse-by-camel hostage at right enabled silver dogs to control f3. This led to a 29-turn win.


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

Gold holds a camel hostage in the east, and a double hostage in the center.

In this game, Gold's central horse-by-camel hostage stopped Silver from forcing a western goal; with the silver horse frozen and other silver pieces blocked from advancing, there was nothing to help the silver elephant counter Gold's defense. This would be a strong position for Silver if he could displace the gold camel, but Gold to move can blockade c3 and perhaps move toward a northwestern goal threat. With the southern forces tying each other down, the western gold horse is the strongest free piece; the silver elephant must stay beside c3, and cannot freeze the gold horse in place. One way or another, this horse can soon accomplish something.

Cat and dog hostages[edit]

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

Silver does not have an ideal alignment, but may eventually overload Gold. (Game)

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 threaten the gold camel. Silver might have to capture the h5 rabbit before making any other threat in f6.

Silver would have a greater advantage if her horse held the dog hostage and her camel were free; with the gold elephant stuck defending against a silver horse, the silver elephant and camel together could make a strong threat elsewhere. Like a horse-by-elephant hostage, a dog-by-camel hostage is at best non-ideal in most situations.


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

Gold's dog-by-horse hostage allowed the gold camel to safely advance to g6.

In this game, Gold's early dog-by-horse hostage allowed the gold camel to lead an attack on f6. An early camel advance would often result in a camel hostage, but the southeastern hostage gave Gold time to advance his camel and support it with rabbits.