Psellos
Life So Short, the Craft So Long to Learn

The Schnapsen Log

September 21, 2012

Only Minds Infer (solution)

Martin Tompa

Before we proceed, let’s have a quiz. What do you think is left face-down in the stock? Let me remind you that Katharina led Q from the position below. Determine your answer before reading past the card diagram.

Unseen cards:
Q
KQ
♣ —
ATQ

Your cards:
TK
ATJ
♣ —

Trump: J
Stock: 1 face-down card
Game points: Katharina 4, You 7
Trick points: Katharina 19, You 28

If you think that the face-down card in the stock is one of those two hearts, I agree with you. If Katharina held the heart marriage, she could have safely crossed the 33 point threshold by declaring it. She is a devious player capable of withholding the marriage in order to deceive you, but only when such deception serves her some purpose.

We haven’t yet talked much about making such inferences based on the opponent’s play, but it’s an important tool for your arsenal. We will return to it in the near future.

In today’s deal, knowing what remains in the stock simplifies your planning process dramatically. On one hand, you’re not excited about drawing the heart yourself if you win the trick, as it cuts down on the number of high hearts you will be able to run. But on the other hand, if you duck with J, then Katharina will surely hold the heart marriage after this trick, whether or not your inference about the stock was correct. That means she will get to 44 points immediately. You will take the remaining tricks and be awarded 1 game point.

It’s certainly worth considering whether you can gain 2 game points by winning her lead instead of ducking, so suppose you trump her Q lead with T and draw K (say) from the stock. This produces the following position with you on lead:

Katharina: (19 points)
QJ
Q
♣ —
AT

You: (41 points)
K
ATKJ
♣ —

You seem to be in danger of losing trump control. There is really nothing to be done from this position other than leading A followed by J to force Katharina to trump, in order to equalize your trump lengths. Here is the resulting position, with Katharina on lead:

Katharina: (24 points)
J

♣ —
AT

You: (55 points)
K
TK
♣ —

You have executed a counterforce play, perhaps stumbling into it without having planned it. Katharina is endplayed. She cannot lead a high diamond, because trumping that puts you over 66 points. All she can do is help you pull trumps by leading J, after which you will cross the finish line anyway by cashing a heart. Congratulations! This play earns you 2 game points.

Incidentally, if Katharina was being devious and neither heart is in the stock, that just makes things much easier for you. After trumping her Q, you can simply cash the top two hearts for a total 69 trick points. Katharina is far too good a player to hand you an extra game point in this manner.

© 2012 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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