Zugzwang

(en.wikipedia.org)

63 points | by Qem 2 hours ago

13 comments

  • simonreiff 2 minutes ago
    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.
  • ucarion 1 hour ago
    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 2 hours ago
    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 51 minutes ago
      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.
    • shermantanktop 2 hours ago
      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.
    • alex43578 1 hour ago
      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.

    • pmontra 2 hours ago
      Two teams, one digs holes, the other one fills holes. Maybe an advice by Keynes during the Great Depression.
      • gzread 1 hour ago
        people mock communism for this, but capitalism also does it all the time
    • colechristensen 1 hour ago
      >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 1 hour ago
        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.
        • darkwater 6 minutes ago
          > 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.

        • Sardtok 54 minutes ago
          That nuke they are apparently working has been just around the corner for over 30 years according to Israeli propaganda.
        • colechristensen 17 minutes ago
          Certainly, I was only talking about one side of the conflict, the errors in our own house.
        • gzread 1 hour ago
          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 1 hour ago
        Small correction: Israel has been doing a genocide continually since 1948 - it didn't start in 2023.
        • colechristensen 10 minutes ago
          Stop. "No, but actually it's this!" oneupsmanship does not add to the conversation.
  • The_Blade 11 minutes ago
    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

  • layer8 1 hour ago
    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.
  • haunter 2 hours ago
    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.
  • b3n 33 minutes ago
    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 6 minutes ago
      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.
  • jonasenordin 2 hours ago
    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 2 hours ago
      The difference to a deadlock is that a deadlock is a inability to move, the zugzwang is an obligation to move.
      • alex43578 1 hour ago
        An obligation to move to your disadvantage.
        • Krasnol 1 hour ago
          The disadvantage is the fact that you're obligated to move. The outcome of the move is not determined though.
          • alex43578 1 hour ago
            “Any legal move will worsen their position”, so the outcome of your move is determined to be inherently negative.
            • darkwater 7 minutes ago
              What happens if you don't move in chess? Honest question.
            • layer8 1 hour ago
              More accurately, it’s being forced to move a specific piece despite disadvantages, because not moving it would result in an even worse outcome — as opposed to moving a different piece that you’d otherwise prefer to move. So it means being forced to move that first piece instead of not moving it (instead of moving a different piece).

              And that’s the generalized meaning in German, being forced to act with respect to a specific thing, where you’d normally prefer to keep it in its current state.

            • Krasnol 1 hour ago
              The word has it's use outside the chess world though and there it is as I wrote it.
  • bitshiftfaced 1 hour ago
    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.
    • stabbles 1 hour ago
      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.
  • HocusLocus 2 hours ago
    Do corporations get drawn to AI from a compulsion to make a move addressing it?

    "Fear of missing out"

  • jgalt212 2 hours ago
    The only way to win is not to play.
    • michaelsshaw 52 minutes ago
      Not playing is a losing move.
      • jgalt212 35 minutes ago
        Unless the game is global thermonuclear war.

        I've led the horse to water.

  • mock-possum 2 hours ago
    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.