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2008-02-10

Construct the Sasquatch Seki and win a prize!

Source:
Myron Souris

(click here to download the SGF for the reference diagram above)

Seki appears in many different forms. The above diagram (with the key seki stones marked) shows just a small sampling:

Lower right: a very common 3 stone seki, with no internal eyes.
Upper left: seki with 2 diagonal (unconnected) stones with 1 internal eye.
Upper right: 2 connected stone seki, with 2 internal eyes.
Lower left: the amazing hane seki theme from a Dosetsu masterpiece (see SGF for details).

But a shy, rarely seen Sasquatch Seki exists that has exactly 2 connected internal stones and only 1 internal eye.

Your job: construct the Sasquatch Seki !

For example, the position in the lower right corner has 3, instead of 2, connected stones. The position in the upper left corner has 2 internal eyes, and the 2 stones are not connected. The position in the upper right has 2 connected stones, but has 2, instead of just 1, internal eyes.

For extra credit: Has the Sasquatch Seki occurred in a pro game? If so, where? If not, why not?

Submit your response to the Problem of the Week Editor . Submissions will remain open for at least 2 weeks, but may remain open longer depending on the level and quality of responses. The Problem Editor's judgement is final. The best earliest response will win 2 back issues of Go World magazine! In case of a tie, the winner will be the person who can most quickly say 10 times "Sasquatch Seki" without becoming tongue tied.

The Sasquatch Seki was last sighted in a game at the St. Louis Go Club , where Jason Taff said, "Myron, you may want to come over here to take a look at this beast."

We have a winner!!

Michael LePore's winning solution.
Of all the submissions, Michael's inventive solution was the best. This seki, which extends around the outside of the entire board, has one internal eye at A, and two connected internal stones at B and C.

A less exotic solution.
Here is the Sasquatch Seki position that appeared at the St. Louis Go Club . MasterGo's pattern searching functionality indicates that this kind of seki shape has probably never appeared in a pro game!

Simplest(?) solution.
Here is another Sasquatch Seki position, but this shape can only appear in the corner. Extending the general shape to the center of the board does not work.

Email the Problem Of The Week editor at potw@usgo.org