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Comment by ineedasername | Hacker News Reader

Ah, thanks. I like being wrong on HN because I learn things. What's most interesting to me is why I was wrong, so I'll share: I was thinking in terms of infinite moves when I should have been thinking in terms of non-infinite board states:

A move, though possibly part of an infinite series of moves, is still only one of a finite number of states for the board. And each state can theoretically be evaluated to results in a win/lose/draw for either white/black assuming both player play a perfect game.

Now I'm going to go way outside my comfort zone with the hope of correction or confirmation: Since the nature of chess on a board of of N dimensions is EXPTIME-hard, would chess on an infinite board be NEXPTIME-hard? (And if not, what level of the time hierarchy would that fall under?)

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Chess also has a finite number of moves (at least on a finite board), the 50-move rule and the 3-repetition rule ensure that a game can't last infinitely even if both players want to and ends in a forced draw.

It's actually because of the 5-fold repetition and 75-move rules! The game is not necessarily over at 3 and 50 – you merely have the right to claim a draw.

Both of those require a player to claim the draw. There is no reason within the rules of the game for why it could not be infinite in the # of moves. The rule has also at times been restricted only to tournament play.

Also, if chess was "solved" and board states determined "winnable" after significantly more moves, the rules might very well change to extend that limit.

Something along those lines has happened before: When a combination of pieces have been shown to be "winnable" but might exceed the 50 move rule, exceptions have been made to the rule to allow more time to develop the win. At some point though, the rules went back to 50, but still with conditions about pawn moves, pieces taken, etc.

The history is interesting: 50 was originally chosen (or maybe just compromised on) because players felt than all winnable games could be won in 50 moves or under.

The fivefold repetition rule requires no claim by the players.

Ah, true... Given the double criteria for that (lack of pawn movement) it extends things a bit, but there would still be a finite number of moves.

However on an info it's chess board there would always be a unique board state possible. That doesn't by any means refute your point, only add a twist to things.

Thanks for explaining this, I learned something, too!

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