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No reachable chess position with more than 218 moves

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Re: No reachable chess position with more than 218 moves

#181

Post by margalabargala »

jibal wrote: post #180
margalabargala wrote: post #123

Earlier quoted context omitted.

Thanks for the condescension. It really helps me file your comment's suggestions appropriately. Here's a general rule of thumb: If the options are a) answer someone's question, and b) answer someone's question but also then spend triple the word count telling them it was a stupid question Then picking (b) makes you an asshole. If all you had written was your first sentence this could have been a pleasant interaction…

Pure defensive (and extremely rude and hostile) projection. (And the response is more of the same, and full of fallacies and false statements). There was no condescension in my comment, just an attempt to be helpful (speaking of "suppression", I will attempt that again with this person). I did not say your question was stupid (it wasn't), I said that you were projecting stupidity on the author of the article (I didn'…

That your comment was downvoted to death indicates maybe you should reconsider how you are being perceived if you truly believe you weren't (and still aren't) being condescending. I don't believe my comment was any more rude or hostile than your original one.

If people were to follow your advice as a general rule, that's how we get groupthink, and how learning is suppressed by making people afraid to ask questions. See the children's story "the emperor's new clothes" for an example.

It takes effort to be negative to see a comment opening with the poster saying "am I missing something" and think they're calling the author stupid instead of acknowledging their own ignorance.

Re: No reachable chess position with more than 218 moves

#182

Post by LorenPechtel »

refulgentis wrote: post #130
kelipso wrote: post #84

Earlier quoted context omitted.

Is that weird? I feel like it’s plausible though. Very rare to have chess games with more than 200 moves.

It’s also rare to have one with more than 50 moves. I’m curious if this class of observation will help establish a true bounds. Especially because we don’t have a definition of what it means - my instinct is to first do that, so “infinity” isn’t the obvious upper bound.

The upper bound is a few thousand. A game is considered drawn if no pawn has moved and no piece has been captured for 50 moves. And there's also the threefold repetition rule: if the same exact position (counting things like castling eligibility etc) occurs three times it's drawn.

Re: No reachable chess position with more than 218 moves

#183

Post by LorenPechtel »

LegionMammal978 wrote: post #67
dmurray wrote: post #64

Earlier quoted context omitted.

I believe 8848.5 under modern rules (with the 75-move rule, as in FIDE rules since 2014). There's a reasonably rigorous demonstration here: https://wismuth.com/chess/longest-game.html

Thanks for that link! I was looking for that answer a few years ago, but I couldn't find anyone who had carried it out all the way through (with the cost of "switching control" fully accounted for), nor many people who were even aware of the 75-move rule.

75 move rule?! Did they go and change the 50 move rule or something, because I've never heard of it.

Re: No reachable chess position with more than 218 moves

#185

Post by tln »

refulgentis wrote: post #174
tln wrote: post #162

Earlier quoted context omitted.

What? Lots of serious chess games last more than 50 moves Not sure if I'm reading your comment correctly The upper bound of moves is 8848.5 https://www.reddit.com/r/chess/comments/168qmk6/longest_poss... ... under the rule that after 75 moves without a capture or pawn advancement the game is drawn

You read a comment saying it’s rare to have more than 200 moves, then a reply noting more than 50 is also rare, then suggested you were confused and maybe it was unreadable and asked “What?” because…some games have above 50 moves. shrugs Thanks for note re: upper bound with 75 moves without pawn advancing constraint.

More than 50 moves in a game is hardly rare, hence my surprised reaction

Re: No reachable chess position with more than 218 moves

#186

Post by Nevermark »

I found a position that takes 78,352 moves and can't find a shorter combo. Both white bishops end up on dark squares. You have to castle at just the right moment. There is a race condition with a window far too narrow to be noticeable in any normal play, but a timing analysis uncovered it. There may be more.

Re: No reachable chess position with more than 218 moves

#187

Post by eru »

Tobs40 wrote: post #153
eru wrote: post #2

https://lichess.org/@/Tobs40/blog/there-is-no-reachable-ches... describes how the author removed some more complicated rules in the first pass, and is willing to re-introduce them, if necessary. Ie if the solution found violates them. Interestingly, mixed integer linear programming solvers already support these. The technical term for this is 'row generation'. It comes from the usually way these problems are written…

Hi, author of the Lichess article here. relaxing and omitting chess rules also changed the choice of variables. I did try lazy constraints etc. before diving into the math, but they did not yield a significant speedup. For example, not considering the white king as being in check simplified A LOT. Best regards, Tobi

Thanks!

> relaxing and omitting chess rules also changed the choice of variables.

I wonder if you can recast some of that in terms of (dynamic) row generation?

> I did try lazy constraints etc. before diving into the math, but they did not yield a significant speedup.

Yes, I can believe that. My point wasn't so much that using heuristics like these is somehow bad, but more that the off-the-shelf solvers can be made to cooperate with (many of) your heuristics.

> For example, not considering the white king as being in check simplified A LOT.

I guess you could classify that as branch-and-bound, if you squinted really hard?

Re: No reachable chess position with more than 218 moves

#188

Post by [deleted] »

tln wrote: post #185
refulgentis wrote: post #174

Earlier quoted context omitted.

You read a comment saying it’s rare to have more than 200 moves, then a reply noting more than 50 is also rare, then suggested you were confused and maybe it was unreadable and asked “What?” because…some games have above 50 moves. shrugs Thanks for note re: upper bound with 75 moves without pawn advancing constraint.

More than 50 moves in a game is hardly rare, hence my surprised reaction

[deleted]

Re: No reachable chess position with more than 218 moves

#190

Post by [deleted] »

tln wrote: post #185
refulgentis wrote: post #174

Earlier quoted context omitted.

You read a comment saying it’s rare to have more than 200 moves, then a reply noting more than 50 is also rare, then suggested you were confused and maybe it was unreadable and asked “What?” because…some games have above 50 moves. shrugs Thanks for note re: upper bound with 75 moves without pawn advancing constraint.

More than 50 moves in a game is hardly rare, hence my surprised reaction

[deleted]
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