View source for Template VI1/Other Intrusion on the 1st row

This article deals with a special case in [[defending against intrusions in template VI1]], namely the right-hand ('other') intrusion on the 1st that is not eliminated by [[sub-templates threat]]s.

== Basic situation ==

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R j2 B g7"
/>

Red should go here:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R 1:h5 j2 B g7 E +:i3 +:i4"
/>

The Red 1 hex is connected to the bottom, and threatens to connect to the top through
either one of the "+" hexes.  It is now Blue's move.

== Claim #1: Blue must move in one of the following + squares below ==

If Blue moves to 

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 j2 B g7 E +:e7 +:f6 +:f7 +:g5 +:g6 +:h6 +:h7 +:i3 +:i4 +:i5 +:i6 +:i7"
/>

If not, Red can move to either i3 or i4 and secure a connection.

== Proposed first Red response ==

If Blue moves to {e7, f6, f7, g5, g6}, Red should take i6 and force a Blue response in either i3 or i4.
If Blue moves to {h6, h7, i5, i6, i7}, Red should take f6 and force a Blue response in either i3 or i4.
If Blue takes i3 or i4 direcly, proceed with [[#Response_to_i3|Response to i3]] or [[#Response_to_i4|Response to i4]] instructions below.

== Response to i3 ==

If we've arrived here, Blue has just taken i3, i4 is free, h5 is securely connected to the bottom and Blue has at most one of the "+" squares below (with one exception; see [[#i3_addendum|i3 addendum]]).  In this case, Red should first take j3 and force a Blue response at i4:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 j2 1:j3 B g7 i3 2:i4 E +:e7 +:f6 +:f7 +:g5 +:g6 +:h6 +:h7 +:i5 +:i6 +:i7"
/>

CASE #1: Blue has i5.
SOLUTION: 

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 7:h6 5:i6 j2 j3 3:j5 1:k4 B g7 6:h7 i3 i4 i5 4:i7 2:k5"
/>

CASE #2: Blue has no tiles in {h6, h7, i5, i6, i7}, or has either {h6, h7, i6} (indicated by +).
SOLUTION: 

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 j2 j3 1:j4 3:k5 B g7 i3 i4 2:i5 E +:h6 +:h7 +:i6"
/>

CASE #3: Blue has i7.
SOLUTION:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 j2 j3 1:j4 3:j5 B g7 i3 i4 2:i5 i7 E +:j6 +:j7 +:k5 +:k6 +:k7"
/>

Blue must take one of the + hexes or Red wins.  Now, Red can play i6 and force h7, then play h6 and connect to h5 (which is already securely connected.

== Response to i4 ==

If we've arrived here, Blue has just taken i4, i3 is free, h5 is securely connected to the bottom and Blue has at most one of the "+" squares below (with one exception; see [[#i4_addendum|i4 addendum]]).  In this case, Red should first take h3 and force a Blue response at h4:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R 1:h3 h5 j2 B g7 2:h4 i4 E +:e7 +:f6 +:f7 +:g5 +:g6 +:h6 +:h7 +:i5 +:i6 +:i7"
/>

CASE #1: Blue has g5.
SOLUTION:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R 1:f4 3:f5 5:f6 7:g6 h3 h5 j2 B 2:e5 4:e7 6:f7 g5 g7 h4 i4"
/>

CASE #2: Blue has no tiles in {e7, f6, f7, g5, g6}, or has either {f6, f7, g6} (indicated by +).
SOLUTION:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R 3:e5 1:g4 h3 h5 j2 B 2:g5 g7 h4 i4 E +:f6 +:f7 +:g6"
/>

CASE #3: Blue has e7.
SOLUTION:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R 3:f5 1:g4 h3 h5 j2 B e7 2:g5 g7 h4 i4 E +:c7 +:d6 +:d7 +:e5 +:e6"
/>

Blue must take one of the + hexes or Red wins.  Now, Red can play f6 and force f7, then play g6 and connect to h5 (which is already securely connected.

== i3 addendum ==

I claimed that Blue can have only one of the + hexes but this is not quite true if Blue first "plays out" the secured bridge.  But in this case Red definitely can acquire i6.

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 h6 i6 j2 B f6 g7 i3 i5 E +:e7 +:f7 +:g5 +:g6 +:h7 +:i7"
/>

In this case, Red can still play j3 to force i4, then k4 to force j5, then l5 wins:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R h5 h6 i6 j2 1:j3 3:k4 5:l5 B f6 g7 i3 2:i4 i5 4:j5"
/>

== i4 addendum ==

I claimed that Blue can have only one of the + hexes but this is not quite true if Blue first "plays out" the secured bridge.  But in this case Red definitely can acquire f6.

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R f6 g6 h5 j2 B g5 g7 i4 i6 E +:e7 +:f7 +:h6 +:h7 +:i5 +:i7"
/>

In this case, Red can still play h3 to force h4, then f4 to force f5, then d5 wins:

<hexboard size="7x14"
  coords="full bottom right"
  edges="bottom"
  visible="area(a7,n7,n5,k2,i2,c5)"
  contents="R 5:d5 3:f4 f6 g6 1:h3 h5 j2 B 4:f5 g5 g7 2:h4 i4 i6"
/>

[[category:edge templates]]