Cornering - Revision history

Selinger: Link to KataHex

2023-11-18T14:57:30Z

Link to KataHex

Demer: /* D3 corner move */ showed usually-better move for the defender

2023-05-03T05:34:55Z

‎D3 corner move: showed usually-better move for the defender

Hexanna: move katahex sequences to separate section

2023-05-03T02:03:43Z

move katahex sequences to separate section

Hexanna: add katahex-approved sequences; also, in the last c4 corner move example, Blue 6 is actually not a bad move

2023-04-29T17:45:58Z

add katahex-approved sequences; also, in the last c4 corner move example, Blue 6 is actually not a bad move

Selinger: /* D3 corner move */ Showed a more logical sequence of moves for d3 corner move.

2021-06-28T03:21:37Z

‎D3 corner move: Showed a more logical sequence of moves for d3 corner move.

Selinger: Added another cornering move.

2021-03-31T20:29:10Z

Added another cornering move.

Selinger: Converted to new hexboard diagrams

2020-12-28T18:40:24Z

Converted to new hexboard diagrams

Selinger: typo

2020-10-29T13:58:24Z

typo

Selinger: Added an example of cornering that does not result in a ladder for the opponent.

2020-10-17T01:53:48Z

Added an example of cornering that does not result in a ladder for the opponent.

Selinger: Elaborated example

2020-10-16T22:46:35Z

Elaborated example

@@ Line 69: / Line 69: @@
 ===Strategic considerations===
-The above sequences are useful if one has the goal of climbing to a particular hex, or when space is limited. However, it's not uncommon to have an empty corner with lots of space available, especially on larger boards like 19&times;19. In these cases, the attacker generally shouldn't be fixated on climbing to a particular hex and should aim to "make the most" of her lack of a ladder escape. There are a few ways to do this. KataHex frequently prefers the following Red 7, followed by move 9 at one of (*):
+The above sequences are useful if one has the goal of climbing to a particular hex, or when space is limited. However, it's not uncommon to have an empty corner with lots of space available, especially on larger boards like 19&times;19. In these cases, the attacker generally shouldn't be fixated on climbing to a particular hex and should aim to "make the most" of her lack of a ladder escape. There are a few ways to do this. [[KataHex]] frequently prefers the following Red 7, followed by move 9 at one of (*):
 <hexboard size="8x9"
    coords="hide"

@@ Line 54: / Line 54: @@
 Another useful corner move for second row ladders is this:
-<hexboard size="7x9"
+<hexboard size="7x10"
    coords="hide"
    edges="bottom right"
-   contents="R a6 B a7 R 1:b6 B 2:b7 R 3:c6 B 4:c7 R 5:f5 E *:e2"
+   contents="R a6 b6 1:c6 3:d6 5:g5 B a7 b7 2:c7 4:d7"
    />
-This allows the attacker to [[climbing|climb]] to "*", even without a [[Switchback#Switchback threat|switchback threat]], as follows:
+This allows the attacker to [[climbing|climb]], even without a [[Switchback#Switchback threat|switchback threat]], as follows:
-<hexboard size="7x9"
+<hexboard size="7x10"
    coords="hide"
    edges="bottom right"
-   contents="R a6 B a7 R b6 B b7 R c6 B c7 R f5 B 6:e6 R 7:d6 B 8:d7 R 9:g4 B 10:e5 R 11:f3 B 12:e3 R 13:e4 B 14:d5 R 15:d4 B 16:c5 R 17:e2
+   contents="R a6 b6 c6 d6 g5 7:e6 9:h4 11:g3 13:f2 B a7 b7 c7 d7 6:f6 8:e7 10:f5 12:e4 S area(a1,a5,c5,e3,e1,a1) f1 g1 h1 h2 i1 i2 j1 j2 i3 j3 j4 E *:d3"
-            S all-area(a6,a7,i7,i5,f2,e2,d3,c5,b6)"
    />
-This move has some similarities with [[Tom's move]], although it does not require a [[parallel ladder]]. Note that 5 and 9 are connected to the edge by [[edge template IV2b]]. The shaded area is not required for this move, i.e., it can be occupied by Blue.
+This move has some similarities with [[Tom's move]], although it does not require a [[parallel ladder]]. Note that 5 and 9 are connected to the edge by [[edge template IV2b]]. The shaded area is not required for this - i.e., it can be occupied by Blue - although depending on what's to the left, 13 may again be threatening to connect back to the ladder (most likely by playing at "*").
 ===Strategic considerations===

@@ Line 68: / Line 68: @@
 This move has some similarities with [[Tom's move]], although it does not require a [[parallel ladder]]. Note that 5 and 9 are connected to the edge by [[edge template IV2b]]. The shaded area is not required for this move, i.e., it can be occupied by Blue.
-However, KataHex more commonly prefers the following Red 7, followed by move 9 at one of (*):
+===Strategic considerations===
 <hexboard size="8x9"
    coords="hide"
@@ Line 83: / Line 85: @@
              R 9:h2 B 10:d5 R 11:e3 B 12:c4 R 13:c5 B 14:d4 R 15:d2"
    />
 [[category:ladder]]
 [[category:definition]]

@@ Line 40: / Line 40: @@
              B 6:e5 R 7:f6 B 8:e6 R 9:g3 E *:f5 *:h4 B 10:e4 R 11:f2"
    />
-Note how Red's 9 is connected to the edge via a [[double threat]] at the cells marked "*". If Blue instead plays 6 on the second row, things are generally worse for Blue:
+Note how Red's 9 is connected to the edge via a [[double threat]] at the cells marked "*". If Blue instead plays 6 on the second row, the position transposes to one commonly encountered with the D3 corner move (described below).
 <hexboard size="7x8"
@@ Line 67: / Line 67: @@
    />
 This move has some similarities with [[Tom's move]], although it does not require a [[parallel ladder]]. Note that 5 and 9 are connected to the edge by [[edge template IV2b]]. The shaded area is not required for this move, i.e., it can be occupied by Blue.
 [[category:ladder]]
 [[category:definition]]

@@ Line 63: / Line 63: @@
    coords="hide"
    edges="bottom right"
-   contents="R a6 B a7 R b6 B b7 R c6 B c7 R f5 B 6:e6 R 7:d6 B 8:d7 R 9:g4 B 10:e5 R 11:f3 B 12:d4 R 13:e2
+   contents="R a6 B a7 R b6 B b7 R c6 B c7 R f5 B 6:e6 R 7:d6 B 8:d7 R 9:g4 B 10:e5 R 11:f3 B 12:e3 R 13:e4 B 14:d5 R 15:d4 B 16:c5 R 17:e2
              S all-area(a6,a7,i7,i5,f2,e2,d3,c5,b6)"
    />

@@ Line 1: / Line 1: @@
 In a [[ladder]] situation when no [[ladder escape]] exists, the [[ladder|attacking player]] can [[ladder]] into a corner and create a "quasi-escape piece" at the very last minute. This play is called '''cornering'''.
-Example:
+=== Pivoting ===
 <hexboard size="5x10"
@@ Line 19: / Line 21: @@
 Red could have also cornered earlier, resulting, for example, in a 4th row ladder for Blue.
 Given enough space, the attacker can sometimes get an outcome that is better than merely turning the ladder, though not as good as a [[switchback]]. For example, starting from a 2nd row ladder, the following maneuver lets Red move towards the center, rather than parallel to Blue's edge:
@@ Line 46: / Line 50: @@
 Note that Red's 7 is connected to the edge via [[edge template IV2b]].
 [[category:ladder]]
 [[category:definition]]

← Older revision		Revision as of 13:58, 29 October 2020
Line 1:		Line 1:
−	In a [[ladder]] situation when no [[ladder escape]] exists, the [[ladder\|attacking player]] can ~~into a~~ [[~~corner~~]] and create a "quasi-escape piece" at the very last minute. This play is called '''cornering'''.	+	In a [[ladder]] situation when no [[ladder escape]] exists, the [[ladder\|attacking player]] can [[ladder]] into a corner and create a "quasi-escape piece" at the very last minute. This play is called '''cornering'''.

	Example:		Example:

← Older revision		Revision as of 01:53, 17 October 2020
Line 17:		Line 17:

	Red could have also cornered earlier, resulting, for example, in a 4th row ladder for Blue.		Red could have also cornered earlier, resulting, for example, in a 4th row ladder for Blue.
		+
		+	Given enough space, the attacker can sometimes get an outcome that is better than merely turning the ladder, though not as good as a [[switchback]]. For example, starting from a 2nd row ladder, the following maneuver lets Red move towards the center, rather than parallel to Blue's edge:
		+
		+	<hexboard size="7x8"
		+	coords="hide"
		+	contents="R a6 B a7 R 1:b6 B 2:b7 R 3:c6 B 4:c7 R 5:f4"
		+	/>
		+
		+	Blue now has several options, but all of them allow Red to connect towards the center of the board:
		+
		+	<hexboard size="7x8"
		+	coords="hide"
		+	contents="R a6 B a7 R b6 B b7 R c6 B c7 R f4
		+	B 6:e5 R 7:f6 B 8:e6 R 9:g3 E :f5 :h4 B 10:e4 R 11:f2"
		+	/>
		+	Note how Red's 9 is connected to the edge via a [[double threat]] at the cells marked "*". If Blue instead plays 6 on the second row, things are generally worse for Blue:
		+
		+	<hexboard size="7x8"
		+	coords="hide"
		+	contents="R a6 B a7 R b6 B b7 R c6 B c7 R f4
		+	B 6:d6 R 7:e5 B 8:d5 R 9:e3"
		+	/>
		+	Note that Red's 7 is connected to the edge via [[edge template IV2b]].
		+

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

@@ Line 1: / Line 1: @@
-In a [[ladder situation]] when no [[ladder escape]] exists, the [[attacking player]] can [[Laddering|ladder]] into a [[corner]] and create a "quasi-escape piece" at the very last minute. This play is called '''cornering'''.
+In a [[ladder]] situation when no [[ladder escape]] exists, the [[ladder|attacking player]] can into a [[corner]] and create a "quasi-escape piece" at the very last minute. This play is called '''cornering'''.
 Example:
-<hex>R5 C10 Vc1 Vb3 Hb4 Vc3 Hc4 Vd3 Hd4 Ve3 He4 Vf3 Hf4 Vg3 Hg4 Vi3</hex>
+<hexboard size="5x10"
-This results in a new [[ladder]], but now the attacking player is [[defending player|defending]] instead.
+This results in a new [[ladder]], but now the attacking player is [[ladder|defending]] instead.
 [[category:ladder]]