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No reachable chess position with more than 218 moves

lichess.org

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Re: No reachable chess position with more than 218 moves

#51

Post by Bootvis »

pmontra wrote: post #48
codeulike wrote: post #28

Earlier quoted context omitted.

There are only 9 queens on the board

The caption of the last diagram is "Legal but non-reachable position with 271 moves for White. Corner queens can be replaced with bishops." There are 24 white queens.

I understand this as follows:

Legal: doesn’t break the rules of chess. For example: no pawns on the eighth rank or in check when it’s not their turn.

Reachable: there is a series of moves that lead to this position from the standard starting position.

Re: No reachable chess position with more than 218 moves

#52

Post by tromp »

pmontra wrote: post #27

How can a position with more than 9 white queens be legal? The limit seems to be one queen plus 8 promoted pawns.

The phrasing "Legal but non-reachable " makes clear that they use some notion of legal that differs from the normal one of reachability. It's hard to imagine what sensible notion that could be though. Something like: each side having only one king, no pawns on first/last row, at most one king in check, etc ?!

Re: No reachable chess position with more than 218 moves

#53

Post by unkulunkulu »

BrenBarn wrote: post #20
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"

Yes, very strange that the phrase "possible moves" never occurs in the article. The key word is "possible". The article consistently just uses the phrasing "have moves" but this is not an obvious way of phrasing things to the average person (although I think it's more common in chess lingo).

in chess lingo the most common is “legal moves”

Re: No reachable chess position with more than 218 moves

#54

Post by burnished »

sverhagen wrote: post #37
WithinReason wrote: post #15

Earlier quoted context omitted.

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...?

What other reason would a person have for juxtaposing two statements?

Re: No reachable chess position with more than 218 moves

#55

Post by davedx »

electroly wrote: post #32
davedx wrote: post #31

Earlier quoted context omitted.

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.

Ugh. Sigh, I see it now - I thought that was the white king, because it has quite some white in it.

I will allocate 50% blame to my brain and eyes, and 50% to whoever designed a black king to have so much white in it :P Thanks!

Re: No reachable chess position with more than 218 moves

#57

Post by binarymax »

unkulunkulu wrote: post #50
winternewt wrote: post #47

Earlier quoted context omitted.

I thought it was "there's no position in chess that requires more than 218 moves to reach."

I thought “there is no chess problem that is both reachable from starting position and requires more than 218 moves to solve”

There are no more than 218 ways to interpret this title

Re: No reachable chess position with more than 218 moves

#58

Post by brumar »

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. I was astonished it was remotely possible to do this.

Re: No reachable chess position with more than 218 moves

#59

Post by stavros »

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"

Ah, wow, I read the article wrong all this time, thank you. I thought they meant "the maximum number of moves you can make to reach any chess position is 218", and I was wondering why the article made no sense to me.

Re: No reachable chess position with more than 218 moves

#60

Post by stephenhumphrey »

jmkd wrote: post #34
wodenokoto wrote: post #12

Earlier quoted context omitted.

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.

Huh. I also have that personal policy. Yet this time I jumped first to the comments before reading the article. I’m not certain why. Perhaps I subconsciously intuited that the ambiguity in the headline might be resolved by some of you smart people. Brains are weird; mine is, anyway.
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