coloin wrote:The fact that they all all have a tridagon is probably expected.
It's expected in an informal sense, because all the known BxB ≥ 7 have one - except the 3 old ones in B7B. As these 3 old ones are not related to the pattern (at least not in any obvious way), one can't exclude that new B7B puzzles with no tridagon might appear some day. But it's unlikely with the current search techniques (starting from puzzles that have a tridagon).
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