Difference between revisions of "Tom's move"

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m (→‎Introduction: Spelling. "Breakthrough" is a noun, not a verb.)
(Added proof of the connectedness of Tom's move, moved from "Edge template IV1c")
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== Introduction ==
 
== Introduction ==
  
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'''Tom's move''' is a trick that enables a player to break through a second [[ladder]]. Its name originates from player [[User:Tom239|Tom239]] who devised it during a game (against dj11, on 15 December 2002) on [[Playsite]]. This was not its first use ever, just how it came to be known among hex players on Playsite.
+
'''Tom's move''' is a trick that enables a player to make a connection from a 2nd-and-4th row [[parallel ladder]]. It can also be used to break through a 2nd row [[ladder]] using a single stone on the 4th row, or to connect a single stone on the 4th row to the edge. Its name originates from Tom Ace (player [[User:Tom239|Tom239]]), who devised it during a game against dj11, on 15 December 2002 on [[Playsite]]. This was not its first use ever, just how it came to be known among Hex players on Playsite.
  
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== Minimal example ==
+
== Example ==
 
In this diagram [[Red (player)|Red]] wants to connect to the bottom edge.
 
In this diagram [[Red (player)|Red]] wants to connect to the bottom edge.
  
Line 9: Line 9:
 
  Va5 Va4 Vd3 Vb2 Ha6 Hb4 Hc3 Hd2 He1 Hf1 Hg1 Hh1 Hi1 Hh2 Hi2 Hi3</hex>
 
  Va5 Va4 Vd3 Vb2 Ha6 Hb4 Hc3 Hd2 He1 Hf1 Hg1 Hh1 Hi1 Hh2 Hi2 Hi3</hex>
  
−
It looks impossible to use the single stone on the [[fourth row]] as a [[ladder escape]]. How can it be done? By using '''Tom's move''':
+
It looks impossible to use the single stone on the 4th row as a [[ladder escape]]. How can it be done? By using '''Tom's move''':
  
−
He [[Push (ladder)|pushes]] the ladder until he is right underneath it, and then he plays at 5.
+
Red [[ladder handling|pushes]] the ladder until she is right underneath it, and then she plays at 5.
  
 
<hex>R6 C9 Q1
 
<hex>R6 C9 Q1
Line 17: Line 17:
 
N:on Vb5 Hb6 Vc5 Hc6 Vf4 +e5</hex>
 
N:on Vb5 Hb6 Vc5 Hc6 Vf4 +e5</hex>
  
−
Now the situation is completely identical to that in the [[Tips_and_tricks#Double_ladder_on_2nd_line_escape|Double ladder on 2nd line Escape]]. Blue's natural [[defense]] is to play at (+).
+
== Why Tom's move is connected ==
  
−
<hex>R6 C9 Q1
+
Red has three main threats:
−
Va5 Va4 Vd3 Vb2 Ha6 Hb4 Hc3 Hd2 He1 Hf1 Hg1 Hh1 Hi1 Hh2 Hi2 Hi3
+
 
−
Vb5 Hb6 Vc5 Hc6 Vf4 Sd5 Sf2
+
<hexboard size="5x11"
−
N:on He5 Vg3</hex>
+
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 E *:k2 E *:a3 E *:b3 R d3 E +:g3 R h3 E *:a4 B c4 R d4 R e4 R 1:f4 E +:g4 R 3:h4 B c5 B d5 B e5 B 2:f5 E +:g5 E +:h5"
 +
  />
 +
 
 +
<hexboard size="5x11"
 +
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 R 1:g2 E +:h2 E *:k2 E *:a3 E *:b3 R d3 E +:g3 R h3 E +:i3 E *:a4 B c4 R d4 R e4 E +:g4 E +:h4 E +:i4 B c5 B d5 B e5 E +:f5 E +:g5 E +:h5 E +:i5"
 +
  />
 +
using the [[ziggurat]] and
 +
 
 +
<hexboard size="5x11"
 +
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 E +:g2 E *:k2 E *:a3 E *:b3 R d3 R h3 E *:a4 B c4 R d4 R e4 E +:f4 R 1:g4 B c5 B d5 B e5"
 +
  />
 +
where the group containing 1 is connected to the left via one of the spots marked with + and trivially to the bottom.
 +
 
 +
The overlap in which Blue has to play:
 +
 
 +
<hexboard size="5x11"
 +
  coords="none"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 E *:k2 E *:a3 E *:b3 R d3 E a:g3 R h3 E *:a4 B c4 R d4 R e4 E b:g4 B c5 B d5 B e5 E c:f5 E d:g5"
 +
  />
 +
 
 +
The 4 different moves are now considered one by one.
 +
 
 +
If Blue moves at a:
 +
<hexboard size="5x11"
 +
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 E *:k2 E *:a3 E *:b3 R d3 B 1:g3 R h3 E *:a4 B c4 R d4 R e4 R 2:f4 R 4:g4 B c5 B d5 B e5 B 3:f5"
 +
  />
 +
The group containing 4 is now connected to the bottom via the template [[Edge_template_III2b|III-2-b]] 
 +
 
 +
If Blue moves at b:
 +
<hexboard size="5x11"
 +
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E +:h1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 R 4:i2 E *:k2 E *:a3 E *:b3 R d3 E +:g3 R h3 E *:a4 B c4 R d4 R e4 R 2:f4 B 1:g4 B c5 B d5 B e5 B 3:f5"
 +
  />
 +
  The group containing 4 is now connected to the left by one of the threads marked with + and to the bottom via the template [[Edge_template_IV2b|IV-2-b]]
 +
 
 +
If Blue moves at c:
 +
<hexboard size="5x11"
 +
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 R 4:g2 E *:k2 E *:a3 E *:b3 R d3 R h3 E *:a4 B c4 R d4 R e4 B 3:f4 R 2:g4 R 6:i4 B c5 B d5 B e5 B 1:f5 B 5:g5"
 +
  />
 +
If Blue plays 3 before 5, Red can play 4 before 6.
 +
 
 +
If Blue moves at d:
 +
<hexboard size="5x11"
 +
  coords="hide"
 +
  edges="bottom"
 +
  visible="area(g1,c5,k5,k3,i1)"
 +
  contents="E *:a1 E *:b1 E *:c1 E *:d1 E *:e1 E *:f1 E *:j1 E *:k1 E *:a2 E *:b2 E *:c2 E *:d2 R f2 E *:k2 E *:a3 E *:b3 R d3 R h3 E *:a4 B c4 R d4 R e4 R 2:f4 R 4:i4 B c5 B d5 B e5 B 3:f5 B 1:g5"
 +
  />
 +
So all of Blue's blocking attempts fail.
 +
 
 +
== See also ==
  
−
Now Red´s two pieces at g3 and f4 are [[Connection|connected]] to the [[bottom edge]] via [[edge template IV2b]], and his [[ladder]] can thus connect to the bottom edge in [[Multiple threats|two different ways]], by playing in either of the starred [[Hex (board element)|cells]].
+
* [[Tips_and_tricks#Double_ladder_on_2nd_line_escape|Double ladder on 2nd line escape]]
  
 
[[category:ladder]]
 
[[category:ladder]]
 
[[category:Advanced Strategy]]
 
[[category:Advanced Strategy]]

Revision as of 05:58, 9 December 2020

Introduction

Tom's move is a trick that enables a player to make a connection from a 2nd-and-4th row parallel ladder. It can also be used to break through a 2nd row ladder using a single stone on the 4th row, or to connect a single stone on the 4th row to the edge. Its name originates from Tom Ace (player Tom239), who devised it during a game against dj11, on 15 December 2002 on Playsite. This was not its first use ever, just how it came to be known among Hex players on Playsite.

Example

In this diagram Red wants to connect to the bottom edge.

abcdefghi123456

It looks impossible to use the single stone on the 4th row as a ladder escape. How can it be done? By using Tom's move:

Red pushes the ladder until she is right underneath it, and then she plays at 5.

abcdefghi12345651324

Why Tom's move is connected

Red has three main threats:

132
1

using the ziggurat and

1

where the group containing 1 is connected to the left via one of the spots marked with + and trivially to the bottom.

The overlap in which Blue has to play:

abcd

The 4 different moves are now considered one by one.

If Blue moves at a:

1243

The group containing 4 is now connected to the bottom via the template III-2-b

If Blue moves at b:

4213
  The group containing 4 is now connected to the left by one of the threads marked with + and to the bottom via the template IV-2-b

If Blue moves at c:

432615

If Blue plays 3 before 5, Red can play 4 before 6.

If Blue moves at d:

2431

So all of Blue's blocking attempts fail.

See also

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