Psellos
Life So Short, the Craft So Long to Learn

The Schnapsen Log

September 29, 2012

What Else Can Be Inferred? (solution)

Martin Tompa

Do you have a guess which card remains face-down in the stock? There are no unseen marriages possible, so this time it’s not a marriage mate to be inferred. Take another look at today’s position and see if there’s some other card you might infer. Remember that Katharina led Q from this position:

Unseen cards:
Q
TQ
♣ TQ
J

Your cards:


♣ AK
ATQ

Trump: K
Stock: 1 face-down card
Game points: Katharina 4, You 4
Trick points: Katharina 30, You 16

Why would’t Katharina exchange J for K before leading? Whenever your opponent fails to exchange the trump when on lead, it is most likely that the trump jack is still in the stock. Today is no exception. That last mystery card in the stock is likely to be J. That is good news for you, since you can prevent Katharina from crossing the 33-point threshold on this trick by trumping her lead, knowing that you will draw a replacement trump from the stock.

Here is the position if you trump with Q and do draw J from the stock:

Katharina: (30 points)

TQ
♣ TQ
K

You: (22 points)


♣ AK
ATJ

From this position, running all your trumps and then cashing ♣A will give you enough trick points to win the deal and gain 2 game points.

You know that Katharina is a tricky player, and fully capable of trying to deceive you about her hand by not exchanging the trump even if she does hold J. After all, she’s not really any better off exchanging and holding K instead of J, since you are probably going to be able to pull whatever trump she holds once the stock is exhausted. On the other hand, Katharina is a good player, and won’t try to deceive you unless the deception could help her.

But just to be safe, before you trump her lead it’s worth considering what else you might draw from the stock if she’s deceiving you. The only card you could draw that wouldn’t allow you to run your winners and win the deal is Q. This would be the position, with you on lead:

Katharina: (30 points)

T
♣ TQ
KJ

You: (22 points)

Q
♣ AK
AT

From this position, cashing your 3 winners would only bring you to 63 trick points, and Katharina would win the deal. Do you see a better play from this position?

Your holding of ♣AK opposite Katharina’s ♣TQ should suggest an elimination play to you. Play AT to eliminate Katharina’s trumps, and then throw her in by leading Q. She will be endplayed, forced to open up the club suit and hand you the last two tricks and 1 game point.

But this is an unlikely scenario. Most likely, your inference of J is correct.

© 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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