RE: [computer-go] Complicated seki with Ko
Many Faces recognizes simple sekis in playouts. It's pretty important to play well, since a lot of corner situations end in seki (when played poorly by the playouts). -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Jason House Sent: Tuesday, June 30, 2009 10:25 AM To: computer-go Subject: Re: [computer-go] Complicated seki with Ko Is it possible to explicitly use a monospace font? I can't read your board positions. I haven't heard of any handling of seki in playouts except for Remi's CrazyStone. I don't think he's ever given specifics on how he did it. Maybe he'll respond to your e-mail? Sent from my iPhone On Jun 26, 2009, at 1:37 PM, Brian Sheppard sheppar...@aol.com wrote: Here is a position that exposed some bugs in Pebbles. Maybe it will help you. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. X is already doomed in this position. The bottom O group is in a seki with the X group at right. O cannot play J6 self-atari. X cannot fill in J8 and then play J6, and after X J6, O captures and X cannot recapture. So it will be dual life. Because the top of the board is O's, O have more than half the board, even without komi. The playouts have to handle certain issues well in order to find that. The first point is to filter out plays that make self-atari on large groups. This will cause the rest of the board to fill up until only the seki remains. The the playout will be in a position like the following: 1 2 3 4 5 6 7 8 9 A - O - O O - O O - B O - O - O O - O O C - O O - O - O O - D X X X O O O O O O E - X X X X O X O O F X X - X O X X X X G X - X X O O X X - H X X X O - O O X X J X - X O O - X - X X to play. Pebbles does not detect superko in playouts, so this position will loop forever with J6/J8/J7/pass. In Pebbles, infinite games were scored as draws. I changed that to give the win to O on the basis of its preponderance of material. (No doubt that will bite me at some point.) Even if we detect the superko repetition, it seems to me that we are only getting the right answer by accident. For instance, if X plays J6 then after J8/J7 there is no move for X, so X has self-ataried himself. Another possibility if to see that X's J6 is atari and also self- atari, so X can look for the approach move. In this case X would play J8 instead of J6 which avoids the ko. Then the seki is obvious. How do other programs handle this case? ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
RE: [computer-go] Complicated seki with Ko
With X to move, Many Faces immediately gives about a 1% win rate, and after a few seconds, resigns, showing 23742 playouts with 0.5% win rate. 10 ply principal variation, staring with A7. I don't have any special code to detect superko or give-2, get-1 in playouts, but the playouts don't generate self- atari moves in a seki, so I think it never tries J6 for either side. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Brian Sheppard Sent: Friday, June 26, 2009 10:37 AM To: computer-go@computer-go.org Subject: [computer-go] Complicated seki with Ko Here is a position that exposed some bugs in Pebbles. Maybe it will help you. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. X is already doomed in this position. The bottom O group is in a seki with the X group at right. O cannot play J6 self-atari. X cannot fill in J8 and then play J6, and after X J6, O captures and X cannot recapture. So it will be dual life. Because the top of the board is O's, O have more than half the board, even without komi. The playouts have to handle certain issues well in order to find that. The first point is to filter out plays that make self-atari on large groups. This will cause the rest of the board to fill up until only the seki remains. The the playout will be in a position like the following: 1 2 3 4 5 6 7 8 9 A - O - O O - O O - B O - O - O O - O O C - O O - O - O O - D X X X O O O O O O E - X X X X O X O O F X X - X O X X X X G X - X X O O X X - H X X X O - O O X X J X - X O O - X - X X to play. Pebbles does not detect superko in playouts, so this position will loop forever with J6/J8/J7/pass. In Pebbles, infinite games were scored as draws. I changed that to give the win to O on the basis of its preponderance of material. (No doubt that will bite me at some point.) Even if we detect the superko repetition, it seems to me that we are only getting the right answer by accident. For instance, if X plays J6 then after J8/J7 there is no move for X, so X has self-ataried himself. Another possibility if to see that X's J6 is atari and also self-atari, so X can look for the approach move. In this case X would play J8 instead of J6 which avoids the ko. Then the seki is obvious. How do other programs handle this case? ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
RE: [computer-go] Re: fuego strength
Is cgos working? It tried putting Many faces on 19x19 a few days ago. It logged it on, and told it there would be a new match later, but there were two programs on and it kept playing them against each other over and over without scheduling ManyFaces, so after a few hours I killed it. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Thomas Lavergne Sent: Friday, June 26, 2009 12:22 AM To: computer-go Subject: Re: [computer-go] Re: fuego strength On Wed, Jun 24, 2009 at 12:39:05PM -0400, Jason House wrote: That raises an interesting point. I've also put bots up in a setup and forget scenario, but inevitably the bit is off of CGOS within a few days and I had no idea when it went down. What's the right way to solve this issue so such altruistic bots can be more easilly maintained? This may also help the anchor absence issue too. If cgosclient not only stall but really crash (due to itself, your program or more probably a network failure) you can just put it in script with a loop : runme.sh: #!/bin/sh while true do cgosclient done I've done this in the past and it works well. I suppose you can do something similar on Windows, but as I know almost anything about windows I can't you for it. I recomand putting a 'mail' in the loop for sending you informations about the crash. And to be gently with the server, adding a 'sleep x' in order to wait a bit before reconnecting. Tom -- Thomas LavergneEntia non sunt multiplicanda praeter necessitatem. (Guillaume d'Ockham) thomas.laver...@reveurs.orghttp://oniros.org ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Scoring - step function or sigmoid function?
Darren, this sounds like a good insight, but only if a very large number of playouts have been performed. By contrast, the original poster writes: But in the opening, where the scoring leaves are 300 moves away from the root, surely a putative half point win doesn't translate to a significant advantage, where as a 100 This I don't buy. If the scoring leaves are 300 moves away, any random playout is way too unreliable to take the score into account. You might as well generate a score randomly. It could be a 100 point win on the first and 100 point loss on the second. In that case, it will be much safer to use Fuego's approach of slightly modifying the playout score from [0.0,1.0] to [0.0+s,1.0-s] where s depends on the size of the win relative to the board size. It is also worth bearing in mind - again, only if the state space was only very superficially searched - that winning by large margins can entail taking large risks. Human players do that only when behind and otherwise actively seek the safer route. Christian On 01/07/2009 04:23, Darren Cook wrote: It seems to be surprisingly difficult to outperform the step function when it comes to mc scoring. I know that many surprises await the mc adventurer, but completely discarding the final margin of victory just can't be optimal. ... an mc program, holding on to a half point victory in the endgame, is a thing of beauty and terror. But in the opening, where the scoring leaves are 300 moves away from the root, surely a putative half point win doesn't translate to a significant advantage, where as a 100 point win would. I had a breakthrough in my understanding of why it is surprisingly difficult to outperform the step function when analyzing some 9x9 games with Mogo and ManyFaces. Let's see if I can extract that insight into words... I observed that in many situations I could map the winning percentage to the final score. E.g. 50-55%: 0.5pt 55-60%: 1.5pt 60-65%: 2.5pt etc. It wasn't as clear cut as that. In fact what I was actually noticing was if I made a 1pt error the winning percentage for the opponent often jumped by, say, 5%. Thinking about why... In a given board position moves can be grouped into sets: the set of correct moves, the set of 1pt mistakes, 2pt mistakes, etc. Let's assume each side has roughly the same number of moves each in each of these groupings. If black is winning by 0.5pt with perfect play, then mistakes by each side balance out and we get a winning percentage of just over 50%. If he is winning by 1.5pt then he has breathing space and can make an extra mistake. Or in other words, at a certain move he can play any of the moves in the correct moves set, or any of the moves in the 1pt mistakes set, and still win. So he wins more of the playouts. Say 55%. If he is winning by 2.5pts then he can make one 2pt mistakes or two 1pt mistakes (more than the opponent) and still win, so he wins more playouts, 60% perhaps. And so on. My conclusion was that the winning percentage is more than just an estimate of how likely the player is to win. It is in fact a crude estimator of the final score. Going back to your original comment, when choosing between move A that leads to a 0.5pt win, and move B that leads to a 100pt win, you should be seeing move B has a higher winning percentage. Darren ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
RE: [computer-go] Passing and RAVE/AMAF
I use Many Faces' knowledge. If the Many Faces engine says the game is in endgame and there are no dame left, then pass is enabled in that node of the UCT search. The game is in endgame if enough moves have been played, and all groups are settled (either alive or dead). The question is, what about passing? That presumably doesn't get counted as a good future move in AMAF, so how can passing gain wins (or runs, for that matter) when it's the right move (e.g., when there is a seki on the board)? Peter Drake http://www.lclark.edu/~drake/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
[computer-go] Complicated seki with Ko
With X to move, Many Faces immediately gives about a 1% win rate, and after a few seconds, resigns, showing 23742 playouts with 0.5% win rate. 10 ply principal variation, staring with A7. I don't have any special code to detect superko or give-2, get-1 in playouts, but the playouts don't generate self- atari moves in a seki, so I think it never tries J6 for either side. How does MF recognize that it is a seki without analyzing what happens in the ko? The eye on H5 is false if X can fill J6, so it is premature to use the both sides have an eye with only shared liberties rule. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Re: fuego strength
It is working. That is pretty odd that it would not get scheduled. As for the new server, I want to do a test and then a switchover soon, the code is in a state where it is usable.It will not schedule the same pairing twice in a row unless those are the only 2 players. I do not want to put it up until I can be highly available in case there are troubles. This weekend I will be out Fri-Sun and I'll be away today and tomorrow - so it will be next week. But I'm eager to get it going and I hope a lot of people will help me test it. - Don On Wed, Jul 1, 2009 at 2:18 AM, David Fotland fotl...@smart-games.comwrote: Is cgos working? It tried putting Many faces on 19x19 a few days ago. It logged it on, and told it there would be a new match later, but there were two programs on and it kept playing them against each other over and over without scheduling ManyFaces, so after a few hours I killed it. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Thomas Lavergne Sent: Friday, June 26, 2009 12:22 AM To: computer-go Subject: Re: [computer-go] Re: fuego strength On Wed, Jun 24, 2009 at 12:39:05PM -0400, Jason House wrote: That raises an interesting point. I've also put bots up in a setup and forget scenario, but inevitably the bit is off of CGOS within a few days and I had no idea when it went down. What's the right way to solve this issue so such altruistic bots can be more easilly maintained? This may also help the anchor absence issue too. If cgosclient not only stall but really crash (due to itself, your program or more probably a network failure) you can just put it in script with a loop : runme.sh: #!/bin/sh while true do cgosclient done I've done this in the past and it works well. I suppose you can do something similar on Windows, but as I know almost anything about windows I can't you for it. I recomand putting a 'mail' in the loop for sending you informations about the crash. And to be gently with the server, adding a 'sleep x' in order to wait a bit before reconnecting. Tom -- Thomas LavergneEntia non sunt multiplicanda praeter necessitatem. (Guillaume d'Ockham) thomas.laver...@reveurs.orghttp://oniros.org ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Complicated seki with Ko
Valkyria behaves the same as Many Faces in this position. It sees maximum 1% winrate for Black. The seki is not really detected by Valkyria, J6 is simply pruned for both players. For white it is just stupid suicide with too many stones. For black I think I prune this kind of two stone suicide always no matter what the situation is (exception is ko). These prunings are probably wrong in some extremely rare cases. Valkyria handles most simple cases of seki, including bent 4 in the corner, and recently seki where false eyes are true eyes because of seki. In general one does not need to make sure it is seki to prune stupid suicidal move or prune filling in false eyes that are could become real eyes in seki. One just has to prunes moves that looks stupid at the moment, and sort of postpone things. If the situation never change then it is a seki. X cannot fill J6 so in my way of seeing H5 is a real eye. A nice but computationally complex feature of the board representation of Valkyria is that all points that are suicidal or illegal are known at all times for sure. This makes it much easier to analyze these kind of situations. Best Magnus Quoting Brian Sheppard sheppar...@aol.com: With X to move, Many Faces immediately gives about a 1% win rate, and after a few seconds, resigns, showing 23742 playouts with 0.5% win rate. 10 ply principal variation, staring with A7. I don't have any special code to detect superko or give-2, get-1 in playouts, but the playouts don't generate self- atari moves in a seki, so I think it never tries J6 for either side. How does MF recognize that it is a seki without analyzing what happens in the ko? The eye on H5 is false if X can fill J6, so it is premature to use the both sides have an eye with only shared liberties rule. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ -- Magnus Persson Berlin, Germany ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
RE: [computer-go] Complicated seki with Ko
X can't fill J6 because that would be suicide. For the moment, H5 is an eye. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Brian Sheppard Sent: Wednesday, July 01, 2009 4:09 AM To: computer-go@computer-go.org Subject: [computer-go] Complicated seki with Ko With X to move, Many Faces immediately gives about a 1% win rate, and after a few seconds, resigns, showing 23742 playouts with 0.5% win rate. 10 ply principal variation, staring with A7. I don't have any special code to detect superko or give-2, get-1 in playouts, but the playouts don't generate self- atari moves in a seki, so I think it never tries J6 for either side. How does MF recognize that it is a seki without analyzing what happens in the ko? The eye on H5 is false if X can fill J6, so it is premature to use the both sides have an eye with only shared liberties rule. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Complicated seki with Ko
Suicide? Do you mean self-atari? But there must be more to it than that because you don't have a rule that prevents all self-atari, right? David Fotland wrote: X can't fill J6 because that would be suicide. For the moment, H5 is an eye. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Brian Sheppard Sent: Wednesday, July 01, 2009 4:09 AM To: computer-go@computer-go.org Subject: [computer-go] Complicated seki with Ko With X to move, Many Faces immediately gives about a 1% win rate, and after a few seconds, resigns, showing 23742 playouts with 0.5% win rate. 10 ply principal variation, staring with A7. I don't have any special code to detect superko or give-2, get-1 in playouts, but the playouts don't generate self- atari moves in a seki, so I think it never tries J6 for either side. How does MF recognize that it is a seki without analyzing what happens in the ko? The eye on H5 is false if X can fill J6, so it is premature to use the both sides have an eye with only shared liberties rule. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
[computer-go] Complicated seki with Ko
For black I think I prune this kind of two stone suicide always no matter what the situation is (exception is ko). These prunings are probably wrong in some extremely rare cases. How can you tell the difference between this kind of two-stone self-atari, and a self-atari of two stones within an opponent's big eye, which could be necessary for lifedeath? ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
RE: [computer-go] Complicated seki with Ko
Sorry, yes, I meant self atari. Yes, there is more to it :) -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Michael Williams Sent: Wednesday, July 01, 2009 7:47 AM To: computer-go Subject: Re: [computer-go] Complicated seki with Ko Suicide? Do you mean self-atari? But there must be more to it than that because you don't have a rule that prevents all self-atari, right? David Fotland wrote: X can't fill J6 because that would be suicide. For the moment, H5 is an eye. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Brian Sheppard Sent: Wednesday, July 01, 2009 4:09 AM To: computer-go@computer-go.org Subject: [computer-go] Complicated seki with Ko With X to move, Many Faces immediately gives about a 1% win rate, and after a few seconds, resigns, showing 23742 playouts with 0.5% win rate. 10 ply principal variation, staring with A7. I don't have any special code to detect superko or give-2, get-1 in playouts, but the playouts don't generate self- atari moves in a seki, so I think it never tries J6 for either side. How does MF recognize that it is a seki without analyzing what happens in the ko? The eye on H5 is false if X can fill J6, so it is premature to use the both sides have an eye with only shared liberties rule. 1 2 3 4 5 6 7 8 9 A - O - O X - - X - B - X O - O X - O O C - O O - O - X O - D X X X O O O O O O E - O X X X O X O O F - - O X O X X X X G - - X X O O X X - H - O X O - O O X X J - O X O O - X - X X to play. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
RE: [computer-go] Re: fuego strength
I just tried again and it's working now, so Many Faces is on 19x19, running an older version on a slow computer 1.6 Ghz Pentium M. I don't use this computer, so it should stay up. Let me know if it drops off and I can restart it. David From: computer-go-boun...@computer-go.org [mailto:computer-go-boun...@computer-go.org] On Behalf Of Don Dailey Sent: Wednesday, July 01, 2009 4:55 AM To: computer-go Subject: Re: [computer-go] Re: fuego strength It is working. That is pretty odd that it would not get scheduled. As for the new server, I want to do a test and then a switchover soon, the code is in a state where it is usable.It will not schedule the same pairing twice in a row unless those are the only 2 players. I do not want to put it up until I can be highly available in case there are troubles. This weekend I will be out Fri-Sun and I'll be away today and tomorrow - so it will be next week. But I'm eager to get it going and I hope a lot of people will help me test it. - Don On Wed, Jul 1, 2009 at 2:18 AM, David Fotland fotl...@smart-games.com wrote: Is cgos working? It tried putting Many faces on 19x19 a few days ago. It logged it on, and told it there would be a new match later, but there were two programs on and it kept playing them against each other over and over without scheduling ManyFaces, so after a few hours I killed it. David -Original Message- From: computer-go-boun...@computer-go.org [mailto:computer-go- boun...@computer-go.org] On Behalf Of Thomas Lavergne Sent: Friday, June 26, 2009 12:22 AM To: computer-go Subject: Re: [computer-go] Re: fuego strength On Wed, Jun 24, 2009 at 12:39:05PM -0400, Jason House wrote: That raises an interesting point. I've also put bots up in a setup and forget scenario, but inevitably the bit is off of CGOS within a few days and I had no idea when it went down. What's the right way to solve this issue so such altruistic bots can be more easilly maintained? This may also help the anchor absence issue too. If cgosclient not only stall but really crash (due to itself, your program or more probably a network failure) you can just put it in script with a loop : runme.sh: #!/bin/sh while true do cgosclient done I've done this in the past and it works well. I suppose you can do something similar on Windows, but as I know almost anything about windows I can't you for it. I recomand putting a 'mail' in the loop for sending you informations about the crash. And to be gently with the server, adding a 'sleep x' in order to wait a bit before reconnecting. Tom -- Thomas LavergneEntia non sunt multiplicanda praeter necessitatem. (Guillaume d'Ockham) thomas.laver...@reveurs.orghttp://oniros.org ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Complicated seki with Ko
In this case one needs to check that after the two stones are captured the capturing single stone can be recaptured bringing us back to where we started. If it is a big eye there is no recapture. -Magnus Quoting Brian Sheppard sheppar...@aol.com: For black I think I prune this kind of two stone suicide always no matter what the situation is (exception is ko). These prunings are probably wrong in some extremely rare cases. How can you tell the difference between this kind of two-stone self-atari, and a self-atari of two stones within an opponent's big eye, which could be necessary for lifedeath? ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ -- Magnus Persson Berlin, Germany ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Complicated seki with Ko
|- - - - - - - |. * * o . . . |* . * o * . * |o . o o * . . |o * o . * . . |o o o * . . . |. * * * . . . |. . . . . . . |. * . . . . . Black to play and kill :) Christian On 01/07/2009 17:41, Magnus Persson wrote: In this case one needs to check that after the two stones are captured the capturing single stone can be recaptured bringing us back to where we started. If it is a big eye there is no recapture. -Magnus Quoting Brian Sheppard sheppar...@aol.com: For black I think I prune this kind of two stone suicide always no matter what the situation is (exception is ko). These prunings are probably wrong in some extremely rare cases. How can you tell the difference between this kind of two-stone self-atari, and a self-atari of two stones within an opponent's big eye, which could be necessary for lifedeath? ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
