Live data from Hacker News

Number of legal 18x18 Go positions computed. One more to go

tromp.github.io

11–20 of 116 posts

Re: Number of legal 18x18 Go positions computed. One more to go

#11
Anyone here play? It is pretty much the ultimate boardgame. Its like game-theory the game. From the very start you are embroiled in interesting risk/reward and provoking you opponent to overextending type stuff. Great place to play is gokgs.com I actually cant play many strategy games anymore because I realize this is like go with a load of crap thrown on it. My friend and I call this 'false complexity' the game isnt really complex it just has loads of rules and random stuff to familiarise yourself with before getting into the game proper. Its not a great a comparison but I would say something like magic the gathering or Dota would be good contenders for most 'false complexity' attained in a game.

Re: Number of legal 18x18 Go positions computed. One more to go

#12

So, given all the positions, can you tell which one(s) are possible results of another position after another turn? // did not know you couldn't do this for chess (paper even pointed to why)

Are you asking whether it's possible to determine all possible 1-move predecessors of a given position?

If so, then yes, that is pretty straightforward. E.g. the last move was either a pass, or a move by White, or a move by Black. For a move by White, it was either a suicide, so could be on any point in an empty region enclosed by Black, or it was no suicide and is one of the points occupied by White in the given position, possibly having captured a Black group in any of the adjacent empty regions enclosed by White.

Re: Number of legal 18x18 Go positions computed. One more to go

#13
post #7

They got 57 legal position for a 2x2 game of go. They're counting all the symmetries. They're not pruning anything. facepalm

Of course they are taking symmetries into account. They are including symmetries in their definition of what the different states are, and thus accounting for them in the count, but they absolutely are pruning symmetries in their implementation. Read the draft of the paper ( https://tromp.github.io/go/gostate.ps ) if you're interested in the techniques.

I'm not pruning any board symmetries. So, yes, the 4x4 position with only one Black stone adjacent to a corner would be counted 8 times (with the Black stone at A2 or A3 or B1 or B4 or C1 or C4 or D2 or D3). The only symmetry that the algorithm takes advantage of is color symmetry; but even there nothing is pruned; the count for a color-normalized state is simply doubled.

Re: Number of legal 18x18 Go positions computed. One more to go

#14

Anyone here play? It is pretty much the ultimate boardgame. Its like game-theory the game. From the very start you are embroiled in interesting risk/reward and provoking you opponent to overextending type stuff. Great place to play is gokgs.com I actually cant play many strategy games anymore because I realize this is like go with a load of crap thrown on it. My friend and I call this 'false complexity' the game isnt…

I've been playing for a couple years now. Easily one of the most enjoyable games I've ever played. The amount of complexity that's hidden in something seemingly so simple so really rewarding to me. I've only managed to get to around 14-11k so far, but I'm looking forward to progressing as I get older in life!

Re: Number of legal 18x18 Go positions computed. One more to go

#15

They got 57 legal position for a 2x2 game of go. They're counting all the symmetries. They're not pruning anything. facepalm

Few people can believe that there are as many as 386,356,909,593 games on the tiny 2x2 board. Needless to say, nothing is pruned there either. A game could visit as many as 48 of the legal positions and have dozens of passes (but only 2 consecutive ones, which ends the game).

Re: Number of legal 18x18 Go positions computed. One more to go

#16
post #12

So, given all the positions, can you tell which one(s) are possible results of another position after another turn? // did not know you couldn't do this for chess (paper even pointed to why)

Are you asking whether it's possible to determine all possible 1-move predecessors of a given position? If so, then yes, that is pretty straightforward. E.g. the last move was either a pass, or a move by White, or a move by Black. For a move by White, it was either a suicide, so could be on any point in an empty region enclosed by Black, or it was no suicide and is one of the points occupied by White in the given pos…

Yeah, that what I'm asking (in a really bad way). I wonder, given a list of positions, how long it would take to build the transitions between them. I would imagine 19x19 would be a "practically forever" type thing.

Re: Number of legal 18x18 Go positions computed. One more to go

#17

Just because the number of legal positions is computed doesn't mean we're anywhere close to "solving" 18x18 Go, right? What's the utility of computing the number of legal positions?

It's just an open problem in combinatorics. Plenty of math doesn't have a specific utility associated with the problems.

Re: Number of legal 18x18 Go positions computed. One more to go

#18
post #12

Earlier quoted context omitted.

Are you asking whether it's possible to determine all possible 1-move predecessors of a given position? If so, then yes, that is pretty straightforward. E.g. the last move was either a pass, or a move by White, or a move by Black. For a move by White, it was either a suicide, so could be on any point in an empty region enclosed by Black, or it was no suicide and is one of the points occupied by White in the given pos…

Yeah, that what I'm asking (in a really bad way). I wonder, given a list of positions, how long it would take to build the transitions between them. I would imagine 19x19 would be a "practically forever" type thing.

It would take at least a nanosecond for each position. Given that 6x6 already has 62567386502084877, it would take at least 724 days. To take "practically forever", 7x7 more than suffices:)

Re: Number of legal 18x18 Go positions computed. One more to go

#19

Just because the number of legal positions is computed doesn't mean we're anywhere close to "solving" 18x18 Go, right? What's the utility of computing the number of legal positions?

Well, it would be interesting problem in combinatorics if you calculated the result in an interesting fashion.

Something like numberjack, which uses constraint programming for combinatorial optimization, would be useful and an article about how someone did this would be useful but alas the op is just a dull statement of a result and doesn't have much merit imho.

Re: Number of legal 18x18 Go positions computed. One more to go

#20

Just because the number of legal positions is computed doesn't mean we're anywhere close to "solving" 18x18 Go, right? What's the utility of computing the number of legal positions?

As George Mallory said when asked "Why did you want to climb Mount Everest?"

"Because it's there."

The number of legal Go positions is a simply defined number that is easily approximated but an enormous computational challenge to compute exactly. I've made it my Mount Everest:-)

I also want to see if the number, written as 19x19 trits in ternary, corresponds to a legal position, which would be totally awesome (but at 1.2% the odds are against it).

Post reply on HN