Like killing Dracula in his tomb!>

Yeah, you're absolutely right. White is in total zugzwang. White resigns in lieu of 40. axb6 axb6, 41. Qh3 gxh3 (Now White has two legal moves - Kh2 or g4) 42. Kh2 (or 42. g4) Qxg2# 0-1

What a lovely zugzwang by Robert Zuk!!!!

In other words, if it were not his move, a player in Zugzwang would draw.

The position in question is the much more common SQUEEZE, wherein one player just wastes time until the player being squeezed has to irrevocably weaken his position, resulting in a completely lost game. Even if the player being squeezed could skip his turn for just one move, he would still be lost.

Given this precise, technical interpretation of Zugzwang, it almost never arises in over-the-board encounters and is reserved for compositions.

However, given that it is a popular chess term that many have misapplied, it is no surprise to see this called a Zugzwang.

My understanding is that a zugzwang occurs when the compulsion to move forces a player to play a losing move. He would really rather sit on his hands and do nothing.

Roll on two moves from the end of the game and we get this ... 40. axb6 axb6

click for larger view

White only has one legal move - 41. Qh3. This is a move he would rather not play as it puts his queen en prise (and leads to unstoppable mate). If he could pass the move he would keep all his pieces, at least for the time being.

The disagreement seems to stem from the fact that white would also lose even if he could pass the move. In this position, if white did nothing for the remainder of the game, black would simply bring his knight over to the queenside, gobble all the white pawns, promote to queen(s) and mate.

But where does it say that it's zugzwang only works when the it's the <only> way to win?

As we have said many times before, there is no single codified and agreed definition of terms like zugzwang.

Robert Brieger may have one definition in mind, but there are equally many other chess players and writers who hold to a different definition.

For example, the definition in Wikipedia talks about zugzwang leading to the position being "significantly weaker". Interestingly, the wikipedia article (one of yours, FSR?) draws a distinction between the use of the term in game theory as opposed to real games:

"In game theory, it specifically means that it directly changes the outcome of the game from a win to a loss. The term is used less precisely in games such as chess; i.e., the game theory definition is not necessarily used in chess (Berlekamp, Conway & Guy 1982:16), (Elkies 1996:136). For instance, it may be defined loosely as "a player to move cannot do anything without making an important concession" (van Perlo 2006:479). Putting the opponent in zugzwang is a common way to help the superior side win a game. In some cases it is necessary to make the win possible (Müller & Pajeken 2008:173)."