Corner template
In Y, players have to link the three sides, and a corner links 2 edges. Similarly to edge templates in Hex there are Corner Templates in Y.
Red is trying to link right and bottom edges through a corner template.
Contents
Corner template II II
Corner template II III
Corner template III III
This one is based on the ziggurat (but of limited use, since it is generally not connected to the third side).
Another one
Because of the threat of reduction to a smaller corner template with e5, Blue has to answer within the marked hexes:
Because of the threat of reduction to two edge templates with move e3, Blue has to answer within the marked hexes:
Because of move c5 reducing, Blue has to answer within the marked hexes:
The only common hex is d5.
Red can then play e4 and connection to both edges is obvious.
Some two-stone templates
The following ones are valid but not necessarily minimal:
