Zugzwang

Zugzwang is a German compound made of the nouns Zug (move) and Zwang (compulsion). Especially in (western) chess it describes the situation in which one player desperately would like to pass, but is forced to move by the rules.
Normally there is no Zugzwang in Go, however see no-pass go (forced to act vs. forced to move).

helopticor?: What about this example from Mathematical Go?

Zugzwang in the upper left  

If white moves first, they get behind by three. If black moves first, they get ahead by only two. Both players want the other one to go first.

BenjaminGeiger: I've heard "mutual zugzwang" used as an explanation for seki . . .

ilan: Sounds like someone got confused. The correct analogy is mutual stalemate, not mutual zugzwang. In a stalemate, the king is safe where it is, but any move puts it it in check. If this is true for both sides it is analogous to a seki by replacing the word "king" with "group" and "check" with "atari."

Anonymous: Websters gives "Tight spot". Is this correct English usage - or is the German loanword used?

ilan: Actually, the difference goes a little deeper. When I was playing chess (30 years ago!), I learned all the principles in books, and in one critical tournament game, I put all my pieces in what I thought was the best strategical place, and then realised that, not only did I have no clue what to do, but I had no clue about which move were even playable in this position. I then decided to completely change my study habits, and concentrate on developing intuition to find candidate moves. This was when I started getting good. I also started winning games in which my opponents had no clue why they lost. The best example was a game I played in the 1975 Canadian Junior Championships against Frank Wang, who was White :

 1.  d4     Nf6
 2.  Nf3    e6
 3.  e3     c5
 4.  Bd3    Nc6
 5.  c3     d5
 6.  Nbd2   Bd6
 7.  e4     cd
 8.  cd     de
 9.  Ne4    Bb4
10.  Bd2    O-O
11.  O-O    Bd2
12.  Qd2

During this opening, I realised that White was the type of player who knew where to put his pieces in what would be considered their most active squares, but who may not know what to do next. With that in mind, I decided to pose this exact problem, so played a move which didn't do very much, but forced him to decide on some original plan of action (a high entropy move, as dicussed in Tom/Go musings):

12.  ...    Kh8

My conjecture proved correct, as he proceeded to completely self-destruct. This became known as the game in which I "zugzwanged Wang." The rest of the game is kind of ugly, but the point is that it is hard to imagine that moving your king into the corner in a quiet position could cause an immediate collapse.

13. Rac1     Nxd4
14. Rfd1     Nxf3
15. gxf3     Bd7
16. Qf4      Nd5
17. Qg3      Bc6
18. Kh1      h6
19. Rg1      Rg8  (again proving what a good move Kh8 was!)
20. Nd6      Qf6
21. Ne4      Qxb2
22. Rc4      Qa3
23. Nd6      Qd3
24. Nf7+     Kh7
25. Re4      g6
26. Nxh6     Nf6
27. Nxg8     Rxg8
28. Qh3+     Kg7
29. Qxe6     Qxf3+
30. Rg2      Bxe4
31. Qe7+     Kh6
    White resigns.

That was weird actually moving game pieces around when replaying the game. It's been a while since I've played anything but Go.

OK, that may sound like a digression, but the point is that in chess, at some point between the opening and middle game, you have to find a plan, or even a move, which is not necessarily easy. And in some situations, the best thing to do is nothing at all. On the other hand, in Go, there is always something going on, and it is easy to find some kind of useful move, even it is not the best one.

Kirk: I see a connection to go, at least for handicap games. When giving a handicap, I used to always try so hard to complicate things with contact plays, cross-cuts, etc, but black would often just get stronger and I would gain little. From that I have learned that it is often better to play a slow, solid move, just reinforcing my position for example, and let black commit to something. It is often the case that you can find a way to make black's move less meaningful -- overconcentrated for example. You are right that all moves have value, but weaker players rarely understand how to make their stones work together effectively in a whole-board sense. It seems white can take profit in gote and let black play a weak move which then gives white another target to exploit. Similar idea, anyway.

Robert Pauli:

• Now I long for the rest of the game, ilan!
• Someone explain me "forced to act vs. forced to move". Don't get it.

Robert Pauli:

• Thanks for the rest, ilan, I'll have a look.
• Concerning "quiet position": Kh8 threatens Nxd4 because sacrificing the Bishop at h7 is no option any more.
• Concerning the term: Inviting the opponent to take the initiativ isn't really Zugzwang. He could have answered Kh1, not?