Edge template VI2a
Contents
The edge template template VI2
Let us first see what possibilities Red has if he moves first.
There are two obvious options:
In both diagrams the possible intrusion points are marked by (+). So we only have to consider the intersection of the intrusion points. They are:
Intrusion at E5 and F5
If Blue blocks at E5 then Red plays F3, reducing to Template IVb
Likewise if blue blocks at F5:
Intrusion at E6
Red threatens to connect via D4. Blue must respond in one of the marked hexs.
The H4 piece is connected to the bottom with template III-1-a, and is connected to the top in two non-overlapping ways:
and
Intrusion at F4
The Red piece at D4 is connected to the bottom. Blue has two direct attempts to block:
Block at F2
Red is now connected to the bottom via template III-1-a. Note that neither of Red's threats overlapped.
Block at E3
The Red piece at H3 is connected to the top and threatening to connect to the bottom. Blue has one defense:
And now Red can connect via B5. Attempts by blue to block the use of the D4 piece as a ladder escape can be shown to not work.
Intrusion at G2
Blue has four options that don't immediately reduce to another edge template:
Block at E4
Red's G3 piece is connected to the top via F3 or H2.
Here Red has created a Ladder escape fork. If blue blocks the ladder Red plays at D3.
Block at D5
And Red has connected. If blue choose to play at E6 instead of E5:
Block at C6
Block at E6
Play continues...
Intrusion at D6 or F6
The D6 case is shown here, but Red's responses work symmetrically for the F6 case.
Red's F5 piece is connected to the bottom. To prevent its connection to the top, Blue must move in one of the marked tiles.
Block at F4
Or, if for move three Blue played G3:
And Red cannot be stopped. Note that this method does not require the three right-most hexs. This means that this method can be used by Red in the symmetrical case of Blue intruding at F6.
Block at G2
Note that Red's F3 piece is connected via the two marked hexs. If Blue had played G3 for move three:
And Red connects.