Corner template
From HexWiki
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.
Corner template II II
Corner template III III
The next one is based on the ziggurat.
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.
