In old-school chess AIs, zugzwang is also of interest because it can break null-move pruning[0], which is a way to prune the search tree. "Null move" just means "skip your turn", and the assumption that skipping your turn is always worse than the optimal move. But in zugzwang positions, that assumption is wrong, so you have to avoid doing null-move pruning.

Stockfish's heuristic for "risk of zugzwang" is basically "only kings and pawns left over", alongside logic for "is null-move pruning even useful right now" [1]:

    // Step 9. Null move search with verification search
    if (cutNode && ss->staticEval >= beta - 16 * depth - 53 * improving + 378 && !excludedMove
        && pos.non_pawn_material(us) && ss->ply >= nmpMinPly && !is_loss(beta))
    {

[0]: https://en.wikipedia.org/wiki/Null-move_heuristic

[1]: https://github.com/official-stockfish/Stockfish/blob/1a882ef...

Relevant for a lot of geopolitical and corporate strategic situations as well. The whole Mideast situation we're in now is because we were in zugzwang and a couple leaders felt the compulsion to move. Taiwan is a similar situation: the best policy is "strategic ambiguity", which is holding for now, but is a bit of an unstable equilibrium.

More relevant to a business site, this is the situation many large corporations find themselves in. Say you're Google and you own an immensely profitable monopoly. The very best thing you can do is nothing; anything you do risks upsetting the delicate competitive equilibrium that you're winning. If you're an executive, how do you do nothing? You can't very well hire thousands of employees to do nothing and pay them to do it. But if you don't have thousands of employees, and your job is doing nothing, how do you justify the millions that they're paying you?

The strategy many executives use is to set different parts of their organization at odds with each other, so that they each create busywork that other employees must do. Everybody is fully utilized, and yet in the big picture nothing changes. Oftentimes they will create big strategic initiatives that are tangential to the golden goose, spending billions on boondoggles that don't actually do anything, because the whole point is to do nothing while seeming like you need thousands of people to do it. And the whole reason for that is because most people are very bad at sitting still, and so if you didn't pay them a whole lot to do nothing useful, the useful stuff they'd be doing would be trying to compete with and unseat you. (You can also see this in the billion dollar paydays that entrepreneurs get when they mount a credible threat of unseating the giant incumbent.)

Two teams, one digs holes, the other one fills holes. Maybe an advice by Keynes during the Great Depression.

That’s a bit cynical to view every corporate action through that lens. There’s certainly the innovator’s dilemma, and plenty of busy work, but to your Google example, plenty of tasks and developments are needed to keep the thing running.

Detect and counter black hat SEO, build or acquire a new product you can spread ads to (Maps, YouTube), create a chatbot that can eventually get ads if search is supplanted. These things support or maintain that monopoly/equilibrium you’re talking about.

>Relevant for a lot of geopolitical and corporate strategic situations as well. The whole Mideast situation we're in now is because we were in zugzwang and a couple leaders felt the compulsion to move. Taiwan is a similar situation: the best policy is "strategic ambiguity", which is holding for now, but is a bit of an unstable equilibrium.

This isn't the case at all.

Obama HAD a deal with Iran that Trump tanked in his first term. Israel did not have to respond to a terrorist attack with genocide. Trump could have said No to Netanyahu who clearly threatened to attack Iran with or without us, it turns out we could indeed put pressure on them not to attack, but TACO.

Everything that's happening in the middle east is a series of blunders by fools.

So Google's strategy is basically paying people to look busy.

The metaphoric meaning of being under “Zugzwang” in German is very similar to “forcing someone’s hand”, from the perspective of the one whose hand is being forced. It means being forced to act, as opposed to not taking action.

That’s what it means in chess. When in zugzwang, you’re in a position where anything you do makes things worse. You would like to make “no move”, but “no move”[1] isn’t an option, so you are forced to do something.

[1] In chess, unlike say go, you can’t pass your move. You have to do something.

Yeah, and I find it pretty interesting that the meanings are not 100% congruent.

In MTG control decks and a subset of that, prison decks are the prime and extreme example of that. Especially something like Lantern Control. It's not about winning, it's about trapping your opponent _not able to_ win.

While normal Go allows passing one's turn, and thus has no zugzwang, there is a No Pass Go variant [1] that forbids passing, where the first player in zugzwang loses the game.

[1] https://senseis.xmp.net/?NoPassGo

"... and a player without a legal play loses..."

That's more like stalemate, not zugzwang.

Edit: Pardon my idiocy. Stalemate is obviously not a loss in chess. So I guess that no-pass go is like neither of these things.

In zugzwang you have legal moves - just none are good for you and all lead to a loss given perfect play.

> just none are good for you and all lead to a loss given perfect play.

That's exactly what it means to be in a lost position; all moves lose. A lost position is only Zugzwang though if the same position with the opponent to move is not lost.

Interestingly, many people will refer to zugzwang when one player only has losing moves and would love to skip their turn altogether, but that's not zugzwang. As a non-example of zugzwang, consider the position with White having a Kb6 and Rc6, and Black just has Kb8. When White moves 1. Rc5, killing a move, Black has no choice but to move 1...Ka8 followed by 2. Rc8#. However, Black is not in zugzwang, because the position is not mutually bad for either player. As a true example of zugzwang, consider the example where White has a Kf5, pawn on e4, Black has a Kd4 and pawn on e5. Now this position is zugzwang because whichever player has to make the next move loses defense of their pawn and with it, the game. For instance, if it's White to move, the game could continue 1. Kf6 Ke4 2. Kg5 Kf3 3. Kf5 e4 and Black will simply march his e-pawn to the 1st rank, promote to a Queen, and checkmate shortly after.

Wikipedia disagrees:

"There are three types of chess positions: either none, one, or both of the players would be at a disadvantage if it were their turn to move. The great majority of positions are of the first type. In chess literature, most writers call positions of the second type zugzwang, and the third type reciprocal zugzwang or mutual zugzwang. "

You're talking about mutual zugzwang

The Wikipedia article goes on to say that other authors describe the second type as a "squeeze" -- I think Kemp uses that term -- and only the mutual or reciprocal kind as a true "zugzwang". I can't remember if it was GM Edmar Mednis or IM Rafael Klovsky who told me many years ago that it's only the mutual scenario that qualifies as a "true" zugzwang, but I'm pretty sure it was one or both of them. Either way, the subject has divided chess authors almost since inception of the term in the first place. You can see the Wikipedia article on Immortal Zugzwang, for instance, which is one of the earliest famous examples of "zugzwang" and is featured in Nimzovitch's classic treatise "My System", and at the same time, many other famous players like IM Andy Soltis and others disagreed with the use of the term for that game.

A great article with some really beautiful examples of zugzwang is: https://www.chesshistory.com/winter/extra/zugzwang.html. There's a very nice discussion at the end as well of a disagreement along just these lines as to what truly constitutes zugzwang, between Hooper and Myers.

Sounds a bit like a Xanatos Gambit

https://tvtropes.org/pmwiki/pmwiki.php/Main/XanatosGambit

Differences being Zugzwang explicitly doesn’t allow a non-move, and I guess assumes a zero sum game? Whereas a Xanatos Gabmit is flexible enough to accommodate both non-moves, and a non-zero-sum setting.

Either way, for your opponent, all roads lead to ruin.

Would it be a fair analogy that the president is in a constant state of Zugzwang - ever subsequent move he makes only ends up making things worse.

A president fundamentally has to try and please two competing groups, the rich lobbyists and the general population. Whatever he does for one, the other will dislike. Nowadays, the rich disliking you as a politician has much more weight, the population has no teeth compared to them.

Zwischenzug (https://en.wikipedia.org/wiki/Zwischenzug) is also a good one and is equivalent to intermezzo as an "in-between move"

i feel like Musk does it on a daily basis with all the heavy artillery he has on the board

The only way to win is not to play.

Saw this exact dynamic play out at Sun in the early 2000s. Staying put while Java licensing imploded wasn't neutral — it was a slow bleed. Sometimes the move is forced whether you acknowledge it or not.

Not playing is a losing move.

Unless the game is global thermonuclear war.

I've led the horse to water.

Seen this play out with suppliers too. Once you've burned a relationship trying to renegotiate, you're stuck — not playing is still a signal. The silence reads as hostile. Sometimes there genuinely isn't a neutral move available, which is its own kind of trap.

Do corporations get drawn to AI from a compulsion to make a move addressing it?

"Fear of missing out"

I recently happened upon a comment (not on HN) that seemed to treat 'zugzwang' as a synonym for 'deadlock'. Possibly because 'zugzwang' sounds really cool and makes your inner voice sound intelligent to your inner ear.

The difference to a deadlock is that a deadlock is a inability to move, the zugzwang is an obligation to move.

An obligation to move to your disadvantage.

It's kind of an illusion when you think about it. "Whose turn it is" is an inseparable part of the game state. If any move makes the game state worse this turn, then the game state was already bad before this turn.

You can infer the game state from way before a zugzwang is played out on the board, and if you're on the losing side of the eventual zugzwang, it's normal to resign.

But if you were allowed to pass your turn, and both players see the draw coming because of a forced repetition, they'll just call it a draw before it even plays out. So the game would play out differently from the same position, if that rule existed. Essentially changing the way you would evaluate any given position.

It's not necessarily an illusion. If chess is solved and it turns out white wins with perfect play, black's first move is zugzwang.

Source? Because I'm pretty sure it's not closed and Wikipedia seems to agree with me:

"No complete solution for chess in either of the two senses is known, nor is it expected that chess will be solved in the near future (if ever)".

https://en.wikipedia.org/wiki/Solving_chess

IIRC that would only be zugzwang if white also wins from a position where it's black's turn but with the colors swapped. If black simply loses from the starting position, that's just... losing, not zugzwang specifically.

Go is a turn based game without this feature (or bug?) because you aren't forced to move, you can instead pass. Both players passing in a row implies neither player thinks they can improve their position and the game ends.

I think zugzwang makes chess endgames richer - the fewer ways you can make a draw, the better, in my opinion. Maybe that's less appealing in go because games can go on for so much longer? At least in 19x19.

I wonder if there's any relation to the strategy of the Gish gallop or Flood the Zone where you overwhelm your opponent with arguments that they have to engage in. Technically, you don't have to engage in the arguments, but the sheer volume can make it seem like you're losing if you don't.

Sounds like a quagmire.

It's more like a situation where you should avoid doing anything. A player in zugzwang who does anything, loses. In chess, it's a position where a player would skip their turn if that option was available, but the rules forbid it, so they're forced to make a move that hurts them.

[edit: Edited to make it clearer that there are cases where only one player is in zugzwang]

"Sometimes the best way to win is to not play at all"

Distributed systems get here constantly. You can't hold state, you can't not hold state, and your pager doesn't care which horn of the dilemma you're on at 3am.