Concurrent Go?

[Milkman]

Does anyone have any analysis or details on games of Go played concurrently? Not simultaneous games against multiple people, but when both players "seal" their moves and play at the same time. If they pick the same space, then that spot is blacklisted. Captures get resolved simultaneously (so a seki might end up getting both groups killed).

I think it'd destroy a lot of the current gameplay, but would it produce anything neat? My biggest concern is that it'd become a game of guessing what the other person wants, introducing chance.

I looked on SL, but couldn't find anything. Any insights?

[Polama]

How would blacklisting positions interact with life and death? Is having one blacklisted eye enough for life? One blacklisted external liberty?

[skydyr]

Also, are moves permanently blacklisted, or just for the turn?

[Milkman]

Sorry, blacklisted for that turn. Otherwise both players could just infinitely choose to play a critical point. So they need to play somewhere else first, then can try to return to that point.

I found a brief description here:
http://fuseki.net/home/simultaneous-go.html

[emerus]

I've never heard of this before. It would introduce chance and gimmicky meta-gaming and it wouldn't resemble Go at all.

[Polama]

Even blacklisting one turn, you can still end up with infinite loops, if there is a clearly largest and second largest move on the board, like life and death for two groups. Then the players switch between blocking the kill for each group in turn.

You could have a ko rule, where you can't replay a move until a stone is actually put down, although you'd risk having to play 2 (then 3, then 4...) blocked moves between every real move. And then at the end, you'd still need to decide how to resolve the permanently blocked positions.

It might be more feasible to play out just the fuseki under these rules, say the first 30 moves. Then do a komi auction or one of those variants to decide who gets first play.

[SmoothOper]

That is an interesting idea, but the blacklisting idea might work, maybe half baked. If you had a very big group in Atari, you would pretty much have to make that move every other turn, which could get old, I kind of expect that it would work itself out, eventually there would be more than one large group in Atari, but then the players would cycle, back and forth.

Maybe instead of a blacklist, introduce a third type of token to mark co-selection. The token when placed on a cross hatch would reduce all connected liberties, and generally behave like an edge. That way you wouldn't get Atari cycles, since the other player couldn't prevent capturing.

[skydyr]

That is an interesting idea, but the blacklisting idea might work, maybe half baked. If you had a very big group in Atari, you would pretty much have to make that move every other turn, which could get old, I kind of expect that it would work itself out, eventually there would be more than one large group in Atari, but then the players would cycle, back and forth.

Maybe instead of a blacklist, introduce a third type of token to mark co-selection. The token when placed on a cross hatch would reduce all connected liberties, and generally behave like an edge. That way you wouldn't get Atari cycles, since the other player couldn't prevent capturing.

This is a pretty interesting idea. I envisioned something similar if the blacklist lasted forever, apart from the loss of liberty.

[palapiku]

eventually there would be more than one large group in Atari, but then the players would cycle, back and forth.

Ahh, but they wouldn't cycle. The moves are made concurrently, so they don't know which move the opponent will pick.

Half the time, they will both choose the same move, blacklist it, then blacklist the remaining move, then tenuki. But the other half the time, they will choose different moves, resolving both groups in one turn.

[PeterN]

These sound like interesting ideas, though it all hinges on how well the blacklisting can be implemented. Other than that I can also see it being a pain having to seal every move.

I'm also imagining just scattering a few of those third token types in "normal" games and wondering what changes that would introduce.

PeterN

[Polama]

eventually there would be more than one large group in Atari, but then the players would cycle, back and forth.

Ahh, but they wouldn't cycle. The moves are made concurrently, so they don't know which move the opponent will pick.

Half the time, they will both choose the same move, blacklist it, then blacklist the remaining move, then tenuki. But the other half the time, they will choose different moves, resolving both groups in one turn.

Only if the two groups are worth identical points. Otherwise, if you choose the lesser group, you're allowing your opponent to take a point advantage. Although the moves are concurrent, there will certainly be situations like this where you can derive the best move for both players, and play it, knowing you'll collide with the opponent but that anything else puts you at a disadvantage.

Maybe instead of a blacklist, introduce a third type of token to mark co-selection. The token when placed on a cross hatch would reduce all connected liberties, and generally behave like an edge. That way you wouldn't get Atari cycles, since the other player couldn't prevent capturing

I was thinking about that too, although it makes it very hard for a player to run at all in confined quarters. We often stretch our lines thin to enclose an enemy group, and then they cut our position to either capture a stone and get out or get forcing moves on other stones to push out sideways. But if we can use these "internal edges" to stop them, by playing where they want to move out, we've put basically an uncapturable stone in their way.

What if these internal edges behave like a wild stone, either black or white? That is, if black is surrounded by white and wild stones, he's captured. If a wild stone is surrounded by one color it's captured. If a wild stone and a black group are connected and all surrounded by white, they all are captured.

[SmoothOper]

eventually there would be more than one large group in Atari, but then the players would cycle, back and forth.

Ahh, but they wouldn't cycle. The moves are made concurrently, so they don't know which move the opponent will pick.

Half the time, they will both choose the same move, blacklist it, then blacklist the remaining move, then tenuki. But the other half the time, they will choose different moves, resolving both groups in one turn.

Suppose you had a move that was worth 20 points in captures or could be connected at the same spot a sure win, then another move that was worth 15 points in capture or a connection also a sure win, I think it is fairly obvious that both players would choose the 20 point group first, then it would be blacklisted, so they would both pick the 15 point move, which would then be blacklisted, at which point they would both pick a different move(assuming super ko rule), at which point they would go back to both picking the 20 point group then the 15 point group... I'm pretty sure it would get old quick.

[SmoothOper]

What if these internal edges behave like a wild stone, either black or white? That is, if black is surrounded by white and wild stones, he's captured. If a wild stone is surrounded by one color it's captured. If a wild stone and a black group are connected and all surrounded by white, they all are captured.

I think you would still have mutual captures issues to resolve, situations where whites chain A and blacks chain B are in mutual atari with one liberty, or even seki, how would that work? All alive, all dead? Throw-ins. Wild stone ko... The mechanics of edges are tough enough to wrap ones head around.

[wineandgolover]

What if the blacklist continues until legal moves are played? So move 100 (same spot, blacklisted) move 101 (same alternate spot, so spot 100 & 101 are blacklisted) move 102 (different locations, so all blacklists cleared).

Does that mostly solve the problem at AMA level?

[skydyr]

What if the blacklist continues until legal moves are played? So move 100 (same spot, blacklisted) move 101 (same alternate spot, so spot 100 & 101 are blacklisted) move 102 (different locations, so all blacklists cleared).

Does that mostly solve the problem at AMA level?

Not really, because if they're big enough, 103 will be the same as 100 and 104 will be the same as 101.