Difference between revisions of "A3 escape trick"

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(Example: Added response to d1.)
(Emphasize that this is a special case of a switchback.)
 
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'''"A3 escape trick"''' is an older name for the [[Switchback#A3 switchback|a3 switchback]]. It dates from a time when this was considered a one-off trick, rather than one of many possible ways of playing a [[switchback]].
  
The term '''a3 escape trick''' denotes the fact that though a red piece on a3 is not part of an [[edge template]] to the [[Top edge|top]], it can still be useful as a [[ladder escape]], when handled correctly.
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The a3 escape trick is a way to handle a 3rd row [[ladder]] approaching a red stone on a3 along the top edge. Although a3 is not sufficient as a [[ladder escape]], it can still be used as a [[switchback]], and can help Red connect when handled correctly.
  
 
== Example ==
 
== Example ==
  
Consider the following position, with red to move:
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Consider the following position, with Red to move:
  
 
<hex>
 
<hex>
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<hexboard size="8x8"
 
<hexboard size="8x8"
 
   coords="show"
 
   coords="show"
   contents="B e2 B f2 B g2 B h2 R a3 B 1:d3 R e3 R f3 R g3 R b4 B 3:d4 B e4 R 2:c5 B e5 R f5 R 4:d6 R e6"
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   contents="B e2 B f2 B g2 B h2 R a3 B 6:d3 R e3 R f3 R g3 R b4 B 8:d4 B e4 R 7:c5 B e5 R f5 R 9:d6 R e6"
 
   />
 
   />
  

Latest revision as of 00:56, 16 March 2022

"A3 escape trick" is an older name for the a3 switchback. It dates from a time when this was considered a one-off trick, rather than one of many possible ways of playing a switchback.

The a3 escape trick is a way to handle a 3rd row ladder approaching a red stone on a3 along the top edge. Although a3 is not sufficient as a ladder escape, it can still be used as a switchback, and can help Red connect when handled correctly.

Example

Consider the following position, with Red to move:

abcdefgh12345678

The a3 escape trick consists of laddering to e3 (making a three-hex gap between the ladder and a3) and then connecting to a3 through a bridge:

abcdefgh1234567842315

Blue's only working response is d3, to which Red responds with another bridge:

abcdefgh123456786879

No matter what Blue plays, Red can either connect with the ladder or directly to the bottom.

Blue can also play c3 instead of d3 but the outcome is the same. If Blue plays d1 instead of d3, Red d3 wins locally (i.e., in this case, Red doesn't even require a connection to e6).

This escape does not always work, as it depends on the size of the board and the pieces already on it.

See also