Difference between revisions of "Multiple threat"

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Threatening to do two different attacks with one move. Often the opponent will only be able to defend against one of the attacks, or defend only partially against both.
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A '''multiple threat''' is when a player threatens to connect in two or more different ways. Ideally, the opponent cannot defend against all of them simultaneously; or at least the presence of multiple threats severely constrains the opponent's options.
  
Whenever possible, a player should make each move achieve at least two different goals or [[threat]]s. Moves that contain only a single threat are generally not hard to meet. If a move contains '''multiple threats''', the opponent may not be able to stop all the threats with a single move.
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Whenever possible, a player should make each move achieve at least two different goals. Moves that contain only a single threat are generally not hard to meet. Moves that contain multiple threats are more difficult, and sometimes impossible, to stop.  
  
A [[Ladder escape|Ladder Escape]] is a typical multiple threat.
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== Connection by double threat ==
  
It is sometimes called fork in hex and other games, and called miai in go.
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The most common example of a multiple treat is a [[double threat]] connecting two of a player's [[group]]s. In the following position, Red's two groups are connected by double threat at the two cells marked "*".
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<hexboard size="4x5"
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  coords="none"
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  edges="none"
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  contents="R a3 b2 c4 d3 e2 B c3 E *:b4 *:d1"
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  />
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If Blue moves at one of the cells marked "*" or its neighbors, Red can respond at the other one, thus guaranteeing a connection between the two groups.
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== Connection by triple threat ==
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Consider [[edge template IV1a]].
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<hexboard size="4x7"
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  coords="none"
 +
  edges="bottom"
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  visible="area(e1,c2,a4,g4,g2,f1)"
 +
  contents="R e1 E a:d2 b:e2 c:f2"
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  />
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The red stone is connected to the edge by (at least) three threats at a, b, and c.
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If Red plays at a or c, Red is connected by a [[ziggurat]]:
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<hexboard size="4x7"
 +
  coords="none"
 +
  edges="bottom"
 +
  visible="area(e1,c2,a4,g4,g2,f1)"
 +
  contents="R e1 R a:d2 S area(c2,a4,d4,d2)"
 +
  />
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<hexboard size="4x7"
 +
  coords="none"
 +
  edges="bottom"
 +
  visible="area(e1,c2,a4,g4,g2,f1)"
 +
  contents="R e1 R c:f2 S area(f2,d4,g4,g2) f1 e2"
 +
  />
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If Red plays at b, Red is connected by [[edge template III1b]]:
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<hexboard size="4x7"
 +
  coords="none"
 +
  edges="bottom"
 +
  visible="area(e1,c2,a4,g4,g2,f1)"
 +
  contents="R e1 R b:e2 S area(d2,b4,f4,f2)-d4"
 +
  />
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Since there is no hex in the overlap of all three threats, Blue cannot block Red's connection.
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== Overlapping threats ==
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In the following situation, Red can connect the two groups by moving at any one of the cells marked "*".
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<hexboard size="4x5"
 +
  coords="none"
 +
  edges="none"
 +
  contents="R d1 b4 c4 B b2 e2 E *:c2 *:d2 *:c3"
 +
  />
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However, these threats are '''overlapping'''; each of the three threatened connections passes through the cell c3. Therefore, by moving at c3, Blue can neutralize all three threats at the same time, denying Red the connection.
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<hexboard size="4x5"
 +
  coords="none"
 +
  edges="none"
 +
  contents="R d1 b4 c4 B b2 e2 B c3"
 +
  />
 +
 
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== See also ==
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* [[Double threat]]
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* [[Mustplay region]]
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* [[AND and OR rules]]
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[[category:Basic Strategy]]
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[[category:Definition]]

Latest revision as of 01:49, 18 May 2022

A multiple threat is when a player threatens to connect in two or more different ways. Ideally, the opponent cannot defend against all of them simultaneously; or at least the presence of multiple threats severely constrains the opponent's options.

Whenever possible, a player should make each move achieve at least two different goals. Moves that contain only a single threat are generally not hard to meet. Moves that contain multiple threats are more difficult, and sometimes impossible, to stop.

Connection by double threat

The most common example of a multiple treat is a double threat connecting two of a player's groups. In the following position, Red's two groups are connected by double threat at the two cells marked "*".

If Blue moves at one of the cells marked "*" or its neighbors, Red can respond at the other one, thus guaranteeing a connection between the two groups.

Connection by triple threat

Consider edge template IV1a.

abc

The red stone is connected to the edge by (at least) three threats at a, b, and c. If Red plays at a or c, Red is connected by a ziggurat:

a
c

If Red plays at b, Red is connected by edge template III1b:

b

Since there is no hex in the overlap of all three threats, Blue cannot block Red's connection.


Overlapping threats

In the following situation, Red can connect the two groups by moving at any one of the cells marked "*".

However, these threats are overlapping; each of the three threatened connections passes through the cell c3. Therefore, by moving at c3, Blue can neutralize all three threats at the same time, denying Red the connection.

See also