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ucarion

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...

nostrademons

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.)

sobellian

If you would lose even if you didn't move, that is not zugzwang. Zugzwang is when, because you must move per the rules of the game, you lose. I don't really see that dynamic in foreign policy. Any country has the option of maintaining its current policy. Whether or not it's wise, the option exists.

akmann

Ofcourse not every situation is zugzwang, but there might be geopolitical situations that fit…

Just the other day Iran offered to open the straight of hormuz, keeping the USA in a state of „they have to respond“ because its expected by their population. In this situation there might be no good choice, so you could call it a zugzwang. But as usual in the states, the administration can just tell some bullshit and get off with it haha

shermantanktop

Geopolitically, the no-action move is rarely unavailable. The motivation to do something rash like start a war out of the blue is often down to the decision of a single person. That leader may have political reasons to do it but they aren’t being forced to do it, as they would in a turn-based game.

pmontra

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

gzread

people mock communism for this, but capitalism also does it all the time

Nifty3929

Capitalism DOES do this all the time, but bankruptcy is the safeguard against this among private companies in a capitalist system. If your outputs are not more valuable than your inputs over a long enough period of time, you will be bankrupt.

There is no such safeguard among publicly run, financed, incented, funded, etc companies or organizations. Their outputs can remain less valuable than their inputs over an indefinite period of time.

alex43578

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.

colechristensen

>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.

alex43578

And on the flip side, Iran could choose not to pursue a nuke and violate the NPT. Hamas could choose not to kill 800-some civilians and take 250 hostages, etc.

Sardtok

That nuke they are apparently working has been just around the corner for over 30 years according to Israeli propaganda.

darkwater

> And on the flip side, Iran could choose not to pursue a nuke and violate the NPT.

Because MAD is the only way to scare away the world's bully.

ogogmad

Iran has said that it's working on nuclear energy, not a bomb. Their pope-level religious leader said it was haram to have nuclear weapons. I know you can't necessarily trust Iran's word, but can you trust Israel's?

colechristensen

Certainly, I was only talking about one side of the conflict, the errors in our own house.

gzread

why would Iran not make a nuke when America keeps bombing countries that don't have nukes, and avoids bombing countries that have nukes (most notably North Korea)? They have all the incentives to have a nuke so they'll stop getting bombed. Obama negotiated to avoid this but Trump ripped it up and bombed them, so they're definitely not going to trust any agreements with the west ever again. From their perspective, their only path to not getting bombed to shit involves having several nukes. It's quite rational for them to do that.

gzread

Small correction: Israel has been doing a genocide continually since 1948 - it didn't start in 2023.

colechristensen

Stop. "No, but actually it's this!" oneupsmanship does not add to the conversation.

layer8

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.

seanhunter

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.

layer8

The corresponding meaning in chess is that you are forced to move a specific peace that you’d normally prefer not to move. See https://news.ycombinator.com/item?id=47988365.

shmeeed

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

layer8

They are congruent in the sense of https://news.ycombinator.com/item?id=47988365.

haunter

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.

tromp

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

Nifty3929

"... 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.

tromp

> 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.

simonreiff

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.

T0Bi

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

simonreiff

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.

Simon_ORourke

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.

newsy-combi

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.

The_Blade

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

HocusLocus

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

"Fear of missing out"

jonasenordin

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.

DonThomasitos

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

alex43578

An obligation to move to your disadvantage.

Krasnol

The disadvantage is the fact that you're obligated to move. The outcome of the move is not determined though.

b3n

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.

bubblyworld

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.

bitshiftfaced

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.

helloplanets

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.

stabbles

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.

T0Bi

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

stabbles

If chess is solved and white wins, black is always in Zugzwang. We might not know.

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