User:Bobson8
From HexWiki
The following pattern guarantees a stone on 7th row to connect to the edge. It was verified by me using HexProver developped by mirefek. Whether this connection is minimal is not known. This partially answers the single-stone 7th row edge template problem (The template exists but the shape is unknown).
To start with, one notice that Red can connect to the edge with a variant of edge template V1b from both sides.
Thus Blue has these possible blocks (a~j, mirrored positions are removed).
For Blue playing a,b,c,d, Red can respond with X,Y,Y,Z respectively. For the rest Red can respond with b.