HexWiki - User contributions [en]

Foiling

2026-03-12T04:15:25Z

GiB: Add Hexworld practice link

To '''foil''' a [[ladder escape]] means to make a move which prevents an [[outpost]] from being used as a [[ladder escape]], and also [[Intrusion|intrudes]] on the outpost's [[connection]] to the [[edge]].

== Example ==

Consider the following position:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He6 Vf3 Vd4 Hd6 Hc1</hex>

[[Red (player)|Red]] has just played f6. In his next move he can either start a [[ladder]] at c7, using f6 as a ladder escape, or he can play g4, making an unbreakable connection from top to bottom. Thus f6 [[double threat|threatens two different connections]].

However it does not secure Red a connection, because there is one vulnerable cell, namely e7:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He6 Vf3 Vd4 Hd6 Hc1 He7</hex>

If [[Blue (player)|Blue]] plays here, he prevents the use of f6 as a ladder escape, and he also intrudes on its [[edge template]] to the bottom. In fact in this position Blue [[win]]s.

So to foil a ladder escape you make a move on the row below the outpost, in the direction of where the ladder will be coming from. Are there other ways to foil?

== Foiling does not always work ==

Consider the following position, which is almost equal the one in the first diagram:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He5 Vf3 Vd4 Hd6 Hc1</hex>

If Blue tries to foil f6 now, Red responds at f7:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He5 Vf3 Vd4 Hd6 Hc1 He7 Vf7</hex>

Observe that the ladder still works, and so does the connection via g4. Since Blue only can stop one of these two, Red wins.

== When does foiling work? ==

In general, it is difficult to figure out when a ladder escape can be foiled. There are some simple rules that apply in some cases.

* A ladder escape fork on the second row is unfoilable.

* A ladder escape fork on the third row is unfoilable if the cell marked "*" is empty, and is not required for the "connection up":

<hex>R5 C10 Vh3 Sg3 Vb1 Vb2 Vb3 Ha5 Hc3 Hc2 Hc1 Pg4</hex>

However, if the cell marked "*" is occupied by Blue, the ladder escape fork can often be foiled; in that case, playing at "+" is the only way of foiling it. Also, if the cell marked "*" is empty, but is required for Red's threatened upward connection, the fork may be foilable by playing at "+", as in the following example:

<hex>R5 C10 Vh3 Sg3 Vb1 Vb2 Vb3 Ha5 Hc3 Hc2 Hc1 Pg4 Hd3 He3 Hf3 V10f1 Hh1 Hi1 Hi2</hex>

Because the cell marked "*" is required for Red's threatened connection to 10, the ladder escape fork is foilable by playing at "+" (but not by playing at "*").

* A ladder escape fork on the fourth row is more complicated. If a 2nd row ladder is already approaching, the fork is unfoilable if the cells marked "*" both are empty (and not required for the "connection up"). Otherwise, it may be foilable, and in that case, playing in one of the cells marked "+" is the only way to foil it.

<hex>R5 C10 Vh2 Se3 Sg2 Vb1 Vb2 Vb3 Hc3 Ha5 Hc2 Hc1 Pe4 Pg3</hex>

If the approaching ladder is a 3rd row ladder, the fork is typically foilable by playing at "+".

<hex>R5 C10 Vh2 Vb1 Vb2 Vb3 Hb4 Hc2 Hc1 Hd2 Ph3</hex>

The foil may not work if Red has a lot of space. For example, the following position is winning for Red (with Blue to move, and assuming "*" connects to the top edge), but Red needs at least the amount of space shown. If any one of the empty cells is occupied by Blue, the position is foilable.

<hex>R6 C9 Vg3 Va2 Va3 Va4 Ha5 Hb3 Hb2 Hc2 Hd2 Va1 Hb1 Hc1 Hd1 He1 Hf1 Hg1 Sh1 Hi1</hex>

To practice: https://hexworld.org/board/#9c1,a7a8a6b6a5b5a4b4a3b3a2b2a1b1g6i4h3g4g3f4f3e4e3d4g2c4f2c3e2c2e1c1f1d3g1d2h1d1h2c5i1d5i2

== Fishing move ==

Playing a foilable move in the hope that the opponent doesn't know how to foil is sometimes called a ''fishing move''. The terminology originated with French-speaking Hex players, such as Mickaël Launay in [https://youtu.be/uAiU7hSiU5A this video], where it is called ''le coup du pêcheur'', literally "the fisherman's move". A fishing move is a kind of trap that is sometimes effective against beginners, but should not be used against experienced players, as it is usually bad for the player who makes it. A fishing move can also sometimes be a last ditch effort by a player who is losing and is desperate for the opponent to make a mistake.

Fishing moves often take the form of playing a [[peep]] in an ascending bridge. In the following example, a red 2nd row ladder is approaching from the left, and the blue bridge is ''ascending'' (relative to the direction of the ladder).
<hexboard size="5x7"
coords="none"
edges="bottom"
contents="R b2 a4 b4 B a5 b5 d3 f2"
/>
Red plays the fishing move 1, hoping that Blue will defend the bridge and Red will get a 2nd row ladder escape. Instead, Blue should foil at 2.
<hexboard size="5x7"
coords="none"
edges="bottom"
contents="R b3 c3 e1 B a5 b5 d3 f2 R 1:e3 B 2:d4 R 3:e2 B 4:e4"
/>
Note that if Red follows through on the bridge threat, the result is a 3rd row ladder for Red, which is typically worse than the 2nd row ladder Red would have gotten otherwise. Playing a fishing move in an ascending bridge usually results in raising the ladder by one row, and is bad for the player who plays it.

On the other hand, playing a peep in a ''descending'' bridge is often useful and not a fishing move. It typically serves to lower the ladder by one row (for example converting a 4th row ladder to a 3rd row ladder), or to escape a 2nd row ladder outright. Consider the following example, with a red 3rd row ladder approaching from the left. Note that the blue bridges are descending (relative to the direction of the ladder).
<hexboard size="5x9"
coords="none"
edges="bottom"
contents="R a3 b3 h1 i2 B a4 b4 d2 e2 f3 g3 h4"
/>
Red's intrusion 3 lowers the ladder from 3rd row to 2nd row, and Red's 9 escapes it. (Moves 4, 5, 10, and 11 are not usually played, but have been included for clarity).
<hexboard size="5x9"
coords="none"
edges="bottom"
contents="R a3 b3 h1 i2 B a4 b4 d2 e2 f3 g3 h4 R 1:c3 B 2:c4 R 3:e3 B 4:f2 R 5:d3 B 6:d5 R 7:e4 B 8:e5 R 9:g4 B 10:h3 R 11:f4"
/>

== References ==

* Mickaël Launay, ''Le Jeu de Hex, Tactique et Strategie - Niveau 1, [https://youtu.be/uAiU7hSiU5A 6. Le coup du pêcheur]'', 2014.

[[category:ladder]]
[[category:definition]]

Foiling

2026-03-12T04:11:10Z

GiB:

To '''foil''' a [[ladder escape]] means to make a move which prevents an [[outpost]] from being used as a [[ladder escape]], and also [[Intrusion|intrudes]] on the outpost's [[connection]] to the [[edge]].

== Example ==

Consider the following position:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He6 Vf3 Vd4 Hd6 Hc1</hex>

[[Red (player)|Red]] has just played f6. In his next move he can either start a [[ladder]] at c7, using f6 as a ladder escape, or he can play g4, making an unbreakable connection from top to bottom. Thus f6 [[double threat|threatens two different connections]].

However it does not secure Red a connection, because there is one vulnerable cell, namely e7:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He6 Vf3 Vd4 Hd6 Hc1 He7</hex>

If [[Blue (player)|Blue]] plays here, he prevents the use of f6 as a ladder escape, and he also intrudes on its [[edge template]] to the bottom. In fact in this position Blue [[win]]s.

So to foil a ladder escape you make a move on the row below the outpost, in the direction of where the ladder will be coming from. Are there other ways to foil?

== Foiling does not always work ==

Consider the following position, which is almost equal the one in the first diagram:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He5 Vf3 Vd4 Hd6 Hc1</hex>

If Blue tries to foil f6 now, Red responds at f7:

<hex>C8 R8 Q1 Vc6 Hb8 Vf6 He5 Vf3 Vd4 Hd6 Hc1 He7 Vf7</hex>

Observe that the ladder still works, and so does the connection via g4. Since Blue only can stop one of these two, Red wins.

== When does foiling work? ==

In general, it is difficult to figure out when a ladder escape can be foiled. There are some simple rules that apply in some cases.

* A ladder escape fork on the second row is unfoilable.

* A ladder escape fork on the third row is unfoilable if the cell marked "*" is empty, and is not required for the "connection up":

<hex>R5 C10 Vh3 Sg3 Vb1 Vb2 Vb3 Ha5 Hc3 Hc2 Hc1 Pg4</hex>

However, if the cell marked "*" is occupied by Blue, the ladder escape fork can often be foiled; in that case, playing at "+" is the only way of foiling it. Also, if the cell marked "*" is empty, but is required for Red's threatened upward connection, the fork may be foilable by playing at "+", as in the following example:

<hex>R5 C10 Vh3 Sg3 Vb1 Vb2 Vb3 Ha5 Hc3 Hc2 Hc1 Pg4 Hd3 He3 Hf3 V10f1 Hh1 Hi1 Hi2</hex>

Because the cell marked "*" is required for Red's threatened connection to 10, the ladder escape fork is foilable by playing at "+" (but not by playing at "*").

* A ladder escape fork on the fourth row is more complicated. If a 2nd row ladder is already approaching, the fork is unfoilable if the cells marked "*" both are empty (and not required for the "connection up"). Otherwise, it may be foilable, and in that case, playing in one of the cells marked "+" is the only way to foil it.

<hex>R5 C10 Vh2 Se3 Sg2 Vb1 Vb2 Vb3 Hc3 Ha5 Hc2 Hc1 Pe4 Pg3</hex>

If the approaching ladder is a 3rd row ladder, the fork is typically foilable by playing at "+".

<hex>R5 C10 Vh2 Vb1 Vb2 Vb3 Hb4 Hc2 Hc1 Hd2 Ph3</hex>

The foil may not work if Red has a lot of space. For example, the following position is winning for Red (with Blue to move, and assuming "*" connects to the top edge), but Red needs at least the amount of space shown. If any one of the empty cells is occupied by Blue, the position is foilable.

<hex>R6 C9 Vg3 Va2 Va3 Va4 Ha5 Hb3 Hb2 Hc2 Hd2 Va1 Hb1 Hc1 Hd1 He1 Hf1 Hg1 Sh1 Hi1</hex>

To practice: https://hexworld.org/board/#9c1,a7a8a6b6a5b5a4b4a3b3a2b2a1b1g6i4h3g4g3f4f3e4e3d4d3c4c3c5h2d5h1

== Fishing move ==

Playing a foilable move in the hope that the opponent doesn't know how to foil is sometimes called a ''fishing move''. The terminology originated with French-speaking Hex players, such as Mickaël Launay in [https://youtu.be/uAiU7hSiU5A this video], where it is called ''le coup du pêcheur'', literally "the fisherman's move". A fishing move is a kind of trap that is sometimes effective against beginners, but should not be used against experienced players, as it is usually bad for the player who makes it. A fishing move can also sometimes be a last ditch effort by a player who is losing and is desperate for the opponent to make a mistake.

Fishing moves often take the form of playing a [[peep]] in an ascending bridge. In the following example, a red 2nd row ladder is approaching from the left, and the blue bridge is ''ascending'' (relative to the direction of the ladder).
<hexboard size="5x7"
coords="none"
edges="bottom"
contents="R b2 a4 b4 B a5 b5 d3 f2"
/>
Red plays the fishing move 1, hoping that Blue will defend the bridge and Red will get a 2nd row ladder escape. Instead, Blue should foil at 2.
<hexboard size="5x7"
coords="none"
edges="bottom"
contents="R b3 c3 e1 B a5 b5 d3 f2 R 1:e3 B 2:d4 R 3:e2 B 4:e4"
/>
Note that if Red follows through on the bridge threat, the result is a 3rd row ladder for Red, which is typically worse than the 2nd row ladder Red would have gotten otherwise. Playing a fishing move in an ascending bridge usually results in raising the ladder by one row, and is bad for the player who plays it.

On the other hand, playing a peep in a ''descending'' bridge is often useful and not a fishing move. It typically serves to lower the ladder by one row (for example converting a 4th row ladder to a 3rd row ladder), or to escape a 2nd row ladder outright. Consider the following example, with a red 3rd row ladder approaching from the left. Note that the blue bridges are descending (relative to the direction of the ladder).
<hexboard size="5x9"
coords="none"
edges="bottom"
contents="R a3 b3 h1 i2 B a4 b4 d2 e2 f3 g3 h4"
/>
Red's intrusion 3 lowers the ladder from 3rd row to 2nd row, and Red's 9 escapes it. (Moves 4, 5, 10, and 11 are not usually played, but have been included for clarity).
<hexboard size="5x9"
coords="none"
edges="bottom"
contents="R a3 b3 h1 i2 B a4 b4 d2 e2 f3 g3 h4 R 1:c3 B 2:c4 R 3:e3 B 4:f2 R 5:d3 B 6:d5 R 7:e4 B 8:e5 R 9:g4 B 10:h3 R 11:f4"
/>

== References ==

* Mickaël Launay, ''Le Jeu de Hex, Tactique et Strategie - Niveau 1, [https://youtu.be/uAiU7hSiU5A 6. Le coup du pêcheur]'', 2014.

[[category:ladder]]
[[category:definition]]