Psellos
Life So Short, the Craft So Long to Learn

The Schnapsen Log

February 5, 2013

Imperfect Information

Martin Tompa

In the Café Abeles with your good friend Peter on this wintry day, you look a little sadly at your dwindling piece of Haselnusstorte and your cup of coffee, which not even an optimist would call half full. “Ah well”, you think, “I’m sure they have more in the kitchen.” Meanwhile, you are only a few tricks into the next deal when you find yourself in this situation:

Unseen cards:

TQ
♣ ATK
TKJ

Your cards:
AK
AK
♣ Q

Trump: J
Stock: 3 face-down cards
Game points: Peter 5, You 5
Trick points: Peter 13, You 38
On lead: You

We haven’t looked at too many positions this early in the deal. When you are at trick 6, you have perfect information about your opponent’s hand, assuming you’ve remembered the played cards correctly. When you are at trick 5, you have nearly perfect information about your opponent’s cards, since there is only one card concealed in the stock and the other 5 are held by your opponent. But at trick 4, where you find yourself now, your information is quite incomplete: nearly half the cards you haven’t yet seen are still in the stock.

How should you proceed from this position? Once you have a good plan, you are welcome to read my analysis.

© 2013 Martin Tompa. All rights reserved.


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About the Author

Martin Tompa

Martin Tompa (tompa@psellos.com)

I am a Professor of Computer Science & Engineering at the University of Washington, where I teach discrete mathematics, probability and statistics, design and analysis of algorithms, and other related courses. I have always loved playing games. Games are great tools for learning to think logically and are a wonderful component of happy family or social life.

Read about Winning Schnapsen, the very first and definitive book on the winning strategy for this fascinating game.

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September
Sidestep a Few Landmines, Sep 2
June
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May
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April
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March
A New Scheme for Remembering Cards, Mar 23
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As Luck Would Have It, Sep 9

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