Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

No reachable chess position with more than 218 moves

lichess.org

Post reply on HN
Print view View original

191–195 of 195 posts

Re: No reachable chess position with more than 218 moves

#191

Post by dmurray »

LorenPechtel wrote: post #183
LegionMammal978 wrote: post #67

Earlier quoted context omitted.

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.

The 50 move rule is still there: either player has the right to claim a draw after 50 moves without a pawn move or a capture. So the game can end then if either player wishes it to (and it almost always will end, because at least one player can expect no better than a draw).

After 75 moves, however, it's not optional, the game has ended. It's still a draw if the game subsequently "ends" in checkmate or a loss on time, though maybe not the players sign the score sheet, move on to the next round, etc.

Re: No reachable chess position with more than 218 moves

#192

Post by [deleted] »

LorenPechtel wrote: post #183
LegionMammal978 wrote: post #67

Earlier quoted context omitted.

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.

[deleted]

Re: No reachable chess position with more than 218 moves

#194

Post by chipsrafferty »

LorenPechtel wrote: post #182
refulgentis wrote: post #130

Earlier quoted context omitted.

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.

I think the upper bound is 6300, then. Each pawn can move 6 times, times 16 pawns, times 50 moves before a game ending draw, plus each capturable piece that can delay the game another 50 moves (15 on each side)

Re: No reachable chess position with more than 218 moves

#195

Post by chipsrafferty »

hyperpape wrote: post #152
salt4034 wrote: post #108

Earlier quoted context omitted.

I think that was an intermediate model. The author updated it, then Gurobi solved the new model to optimality (i.e., the bound became equal to the value of the best solution found). > With this improved model, I tried again and after ~23 000 seconds, Gurobi solved it to optimality!

The article was interesting, but this bit felt a bit like "and then a miracle occurred".

The fractional stuff was poorly explained, I didn't understand it at all.
Post reply on HN