Difference between revisions of "Nozoki"

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Sometimes it's hard to tell if a move is [[Forcing moves|forcing]], i.e. if the nozoki is correct or wrong. Playing correct nozokis is one of the most sophisticated aspects of hex strategy.
 
Sometimes it's hard to tell if a move is [[Forcing moves|forcing]], i.e. if the nozoki is correct or wrong. Playing correct nozokis is one of the most sophisticated aspects of hex strategy.
 
In all following examples red edges are vertical ones and blue edges are horizontal ones.
 
  
 
== Example ==
 
== Example ==
 
<hexboard size="6x6"
 
<hexboard size="6x6"
 
   coords="show"
 
   coords="show"
   contents="R :d3 B :e4 R :e3 B :b3 R :b4 E *:c4 E *:c3"
+
   contents="B :d3 R :e4 B :e3 R :b3 B :b4 E *:c4 E *:c3"
 
   /><br/>
 
   /><br/>
  
In this position blue player can play 2 '''correct nozokis''' - c4 or c3. In case of playing c3, red has to defend with c4. In case of playing c4, red has to defend with c3. Otherwise red loses the game.
+
In this position red player can play 2 '''correct nozokis''' - c4 or c3. In case of playing c3, blue has to defend with c4. In case of playing c4, blue has to defend with c3. Otherwise blue loses the game.
  
Notice that moves on a4, a5, f2 and f3 are '''wrong nozokis'''. Against a4, a5 red has a choice of playing b5 which improves their position. Similarly, against f2, f3 red should play d2.
+
Notice that moves on a4, a5, f2 and f3 are '''wrong nozokis'''. Against a4, a5 blue has a choice of playing b5 which improves their position. Similarly, against f2, f3 blue should play d2.
  
 
== Crucial nozoki ==
 
== Crucial nozoki ==
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<hexboard size="9x9"
 
<hexboard size="9x9"
 
   coords="show"
 
   coords="show"
   contents="R :h4 B :d4 R :e5 B :g6 R :c6 E *:d6"
+
   contents="B :h4 R :d4 B :e5 R :g6 B :c6 E *:d6"
 
   /><br/>
 
   /><br/>
  
The only winning move for blue is the nozoki on d6. If blue misses it the game proceeds as follows and the winner is red.
+
The only winning move for red is the nozoki on d6. If red misses it the game proceeds as follows and the winner is blue.
  
 
<hexboard size="9x9"
 
<hexboard size="9x9"
 
   coords="show"
 
   coords="show"
   contents="R :h4 B :d4 R :e5 B :g6 R :c6 B 1:g4 R 2:g5 B 3:f5 R 4:f6 B 5:e6 R 6:d8 B 7:e7 R 8:e9"
+
   contents="B :h4 R :d4 B :e5 R :g6 B :c6 R 1:g4 B 2:g5 R 3:f5 B 4:f6 R 5:e6 B 6:d8 R 7:e7 B 8:e9"
 
   /><br/>
 
   /><br/>
  
If d6 is played then blue win.
+
If d6 is played then red win.
  
 
<hexboard size="9x9"
 
<hexboard size="9x9"
 
   coords="show"
 
   coords="show"
   contents="R :h4 B :d4 R :e5 B :g6 R :c6 B 1:d6 R 2:d5 B 3:g4"
+
   contents="B :h4 R :d4 B :e5 R :g6 B :c6 R 1:d6 B 2:d5 R 3:g4"
 
   /><br/>
 
   /><br/>

Revision as of 12:14, 19 March 2017

A nozoki (term borrowed from Go) is a forcing move to which opponent has just a single answer to defend against an immediate threat. This situation occurs if one threatens to cut a connection between major groups or key stones of opponent's. The stone causing this threat is called a nozoki.

Sometimes it's hard to tell if a move is forcing, i.e. if the nozoki is correct or wrong. Playing correct nozokis is one of the most sophisticated aspects of hex strategy.

Example

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In this position red player can play 2 correct nozokis - c4 or c3. In case of playing c3, blue has to defend with c4. In case of playing c4, blue has to defend with c3. Otherwise blue loses the game.

Notice that moves on a4, a5, f2 and f3 are wrong nozokis. Against a4, a5 blue has a choice of playing b5 which improves their position. Similarly, against f2, f3 blue should play d2.

Crucial nozoki

There is a great use for playing nozokis. In certain conditions a player can benefit from them and claim victory. Look at the following example:

abcdefghi123456789

The only winning move for red is the nozoki on d6. If red misses it the game proceeds as follows and the winner is blue.

abcdefghi12345678913254768

If d6 is played then red win.

abcdefghi123456789321