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

31–40 of 195 posts

Re: No reachable chess position with more than 218 moves

#31

Post by davedx »

electroly wrote: post #30
davedx wrote: post #29

Earlier quoted context omitted.

But black has no king, so surely the game is over and there are no more legal moves? Why does black have two pawns but no king? I don’t understand any of this

Every board on the page, with the exception of the illegal "all queens" board, has a black king. The king is the one with the cross above the crown. In the first board, the 218 winner, it's at A1.

The first image, which I assume is the solution because the title is 'Reachable chess position with 218 moves for White, published by Petrović in 1964.', has no black king?

Re: No reachable chess position with more than 218 moves

#32

Post by electroly »

davedx wrote: post #31
electroly wrote: post #30

Earlier quoted context omitted.

Every board on the page, with the exception of the illegal "all queens" board, has a black king. The king is the one with the cross above the crown. In the first board, the 218 winner, it's at A1.

The first image, which I assume is the solution because the title is 'Reachable chess position with 218 moves for White, published by Petrović in 1964.', has no black king?

Look again. It's at A1. You may be confusing that symbol with a different piece.

Re: No reachable chess position with more than 218 moves

#33

Post by nabla9 »

codeulike wrote: post #10

They dont really spell it out but they mean "from this position the player has 218 possible legal moves to choose from"

It should be obvious that there are no 8.7 × 10^45 possible chess moves from any chess position. All pieces have less than 32 moves per piece and 19 pieces means less than 608 moves.

Re: No reachable chess position with more than 218 moves

#34

Post by jmkd »

wodenokoto wrote: post #12
codeulike wrote: post #10

They dont really spell it out but they mean "from this position the player has 218 possible legal moves to choose from"

I thought it was "How many moves in a game does it take to reach this position"

Same, which also damages my personal policy of reading the link before any HN comments.

Re: No reachable chess position with more than 218 moves

#35

Post by electroly »

nabla9 wrote: post #33
codeulike wrote: post #10

They dont really spell it out but they mean "from this position the player has 218 possible legal moves to choose from"

It should be obvious that there are no 8.7 × 10^45 possible chess moves from any chess position. All pieces have less than 32 moves per piece and 19 pieces means less than 608 moves.

No, they do mean possible moves and they don't mean maximum length game. There are on the order of 10^45 reachable chess positions. The article did not say that was the number of moves from one position. The article says 218 is the maximum number of moves from one reachable position--it's the whole point of the article!

Re: No reachable chess position with more than 218 moves

#36

Post by amitparikh »

codeulike wrote: post #10

They dont really spell it out but they mean "from this position the player has 218 possible legal moves to choose from"

Right, and by "reachable" they mean it is theoretically possible to get to this board position through a normal (albeit obviously methodically chosen) series of moves.

Re: No reachable chess position with more than 218 moves

#37

Post by sverhagen »

WithinReason wrote: post #15
codeulike wrote: post #10

They dont really spell it out but they mean "from this position the player has 218 possible legal moves to choose from"

Thanks, I misunderstood the entire article. Great writing!

How can those two things be true at the same time? Unless you appreciate misunderstanding what you read...?

Re: No reachable chess position with more than 218 moves

#38

Post by amelius »

What is the least number of bits that can describe any reachable chess board?

update: article says there are approximately 8.7x10^45 reachable chess positions and https://github.com/lechmazur/ChessCounter says this is an upper bound.

(this would correspond to about 153 bits)

Post reply on HN