Re: [computer-go] When is Pass the best move?
Well at least we can be sure that for any two person game, if a position occurs 3 times, at least 2 will have the same player to move ;-)Erik On 11/8/06, John Tromp <[EMAIL PROTECTED]> wrote: The difference between PSK and SSK also comes up in chess.Witness these events taking place yesterday in the Tal Memorialchess festival in Moscow:Morozevich-Carlsen was interesting for a technical reason. White had some advantages but Carlsen locked up the position in sound defence.There was some shuffling around with the pieces, and at one stageMagnus Carlsen approached the deputy arbiter Eduard Dubov to announcethat he intended to play the move 46...Qc7 and produce the same position for a third time on the board. The chief arbiter GeurtGijssen was summoned and he started to check the game with Carlsen inthe analysis room. Gijssen also informed Morozevich about Carlsen'sclaim and invited him to join in the checking. But Morozevich refused. Carlsen and Gijssen replayed the game and came to the conclusion thatindeed the final position had occurred for a third time. A draw wasgiven and both players signed the scoresheets. Afterwards Gijssen had some doubts and again checked the game. It was then that he discoveredthat while the position had appeared three times on the board, it wasnot with the same player having the move. "It means that the claim was wrong and my decision was wrong as well," writes Gijssen in hisreport. He informed Carlsen about this and the young Norwegian wasimmediately ready to continue the game. The organizers tried to reachMorozevich, but he was nowhere to be found. In the end his coach Kuzmin informed the organizers that, in his opinion, the draw shouldstand. And so it did.[http://www.chessbase.com/newsdetail.asp?newsid=3476] This is not the first occurrance of such confusion:In the twentieth game of the 1972 Bobby Fischer-Boris Spassky match(the Match of the Century), Fischer claimed a draw because ofthreefold repetition. Spassky did not dispute it and the arbiter agreed. After the draw had been agreed, it was pointed out that theposition had occurred after White's forty-eighth and fiftieth moves,and again after Black's fifty-fourth move (the final position). So the claim was actually invalid because it was not the same player's turnto move in all three instances (Alexander 1972:137-38).[http://en.wikipedia.org/wiki/Threefold_repetition ]Perhaps positions are more easily recognized than situations...regards,-John___computer-go mailing list computer-go@computer-go.orghttp://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] When is Pass the best move?
The difference between PSK and SSK also comes up in chess. Witness these events taking place yesterday in the Tal Memorial chess festival in Moscow: Morozevich-Carlsen was interesting for a technical reason. White had some advantages but Carlsen locked up the position in sound defence. There was some shuffling around with the pieces, and at one stage Magnus Carlsen approached the deputy arbiter Eduard Dubov to announce that he intended to play the move 46...Qc7 and produce the same position for a third time on the board. The chief arbiter Geurt Gijssen was summoned and he started to check the game with Carlsen in the analysis room. Gijssen also informed Morozevich about Carlsen's claim and invited him to join in the checking. But Morozevich refused. Carlsen and Gijssen replayed the game and came to the conclusion that indeed the final position had occurred for a third time. A draw was given and both players signed the scoresheets. Afterwards Gijssen had some doubts and again checked the game. It was then that he discovered that while the position had appeared three times on the board, it was not with the same player having the move. "It means that the claim was wrong and my decision was wrong as well," writes Gijssen in his report. He informed Carlsen about this and the young Norwegian was immediately ready to continue the game. The organizers tried to reach Morozevich, but he was nowhere to be found. In the end his coach Kuzmin informed the organizers that, in his opinion, the draw should stand. And so it did. [http://www.chessbase.com/newsdetail.asp?newsid=3476] This is not the first occurrance of such confusion: In the twentieth game of the 1972 Bobby Fischer-Boris Spassky match (the Match of the Century), Fischer claimed a draw because of threefold repetition. Spassky did not dispute it and the arbiter agreed. After the draw had been agreed, it was pointed out that the position had occurred after White's forty-eighth and fiftieth moves, and again after Black's fifty-fourth move (the final position). So the claim was actually invalid because it was not the same player's turn to move in all three instances (Alexander 1972:137-38). [http://en.wikipedia.org/wiki/Threefold_repetition] Perhaps positions are more easily recognized than situations... regards, -John ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On Tue, 24 Oct 2006, Heikki Levanto wrote: > On Tue, Oct 24, 2006 at 07:26:34PM +0100, Jacques Basaldúa wrote: > > BTW: In my over 50K master games collection I have only seen 2 games > > with a triple KO. (The whole collection was played out by GnuGo 3.6 > > level 10 to verify/compute the final score.) And I have never seen > > other superkos than triple KO in real top games. In case of triple > > KO all SK definitions lead to the same, so we are probably discussing > > principles rather than facts. > > I believe this to be true for "normal" go, with a suitably large board. > The various ko rules seem to make a difference to pathologically small > board sizes, and other anomalies. Those may be an interesting field of > study, but seem not to be awfully relevant to the game of go, as we know > it. No. The probability of a ko arising is roughly proportional to the area, so it sort of grows quadratically with the side length of the board. I experienced this when generating life and death problems automatically that the percentage of problems with a status ko (given that these are unsettled positions where it matters who moves first) increases with the size of the problems. The same experience was made (and graphically displayed) when generating this data base of monolithic eyes up to size 11 that the positions in which the status is ko grew faster than the number of unsettled positions in general. Thomas > > Just my humble opinion, of course. I am sure to be corrected by more > knowing people on this list if I am wrong. Maybe even if I am not... > > -H > > > -- > Heikki Levanto "In Murphy We Turst" heikki (at) lsd (dot) dk > > ___ > 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] When is Pass the best move?
On Tue, Oct 24, 2006 at 07:26:34PM +0100, Jacques Basaldúa wrote: > BTW: In my over 50K master games collection I have only seen 2 games > with a triple KO. (The whole collection was played out by GnuGo 3.6 > level 10 to verify/compute the final score.) And I have never seen > other superkos than triple KO in real top games. In case of triple > KO all SK definitions lead to the same, so we are probably discussing > principles rather than facts. I believe this to be true for "normal" go, with a suitably large board. The various ko rules seem to make a difference to pathologically small board sizes, and other anomalies. Those may be an interesting field of study, but seem not to be awfully relevant to the game of go, as we know it. Just my humble opinion, of course. I am sure to be corrected by more knowing people on this list if I am wrong. Maybe even if I am not... -H -- Heikki Levanto "In Murphy We Turst" heikki (at) lsd (dot) dk ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
Don Dailey wrote: The only reason to have a KO rule is to prevent by force, long cycles. So I don't see a point in imposing more restrictive conditions than necessary. Talking about superko, I agree at 100%. John Tromp's arguments are sound and probably the best from the _ruleset's_ point of view. But, this is not about the ruleset, its about _the game_. And from the game's point of view the best thing is letting the players play it out. "Authority" should only intervene with a prohibition if there is no other option because the game would not end. So the best would be NSSK applied only if there is no difference in captures during the cycle. Difference in the captures is seen among novices, where one player attacks a stone that does not require being defended and at the end the attacking stones are captured in a snapback. The position is repeated by the player playing correctly. Why should he/she be punished (forced to play an inferior move) if the loop is an error of the opponent who has already lost two (or more) points doing it so he won't do that again? BTW: In my over 50K master games collection I have only seen 2 games with a triple KO. (The whole collection was played out by GnuGo 3.6 level 10 to verify/compute the final score.) And I have never seen other superkos than triple KO in real top games. In case of triple KO all SK definitions lead to the same, so we are probably discussing principles rather than facts. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On Mon, Oct 23, 2006 at 12:23:14PM -0400, Don Dailey wrote: > But now we have one itty bitty practical inconvenience. How to you > conduct tournaments and matches where games can last forever? > > Since GO currently has arbitrary KO rules for practical convenience, why > not introduce another arbitrary but practical rule to handle this > situation?After all, we just got rid of the nuisance KO rule? > > The rule we could introduce (which can be concisely stated) is to set a > move number limit on the game. If a game goes to move N, it is over > and a draw is declared. (Or we could award the game to WHITE if we want > to make draws impossible.) But the problem of too slow tournament games has been solved ages ago with time limits. Since nobody can play an infinite number of stones in a finite time, the game must end at some point. -H -- Heikki Levanto "In Murphy We Turst" heikki (at) lsd (dot) dk ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
Cool idea Dons! I think taking away the ordinary ko rule in this way would have too strong a distorting effect on the game. The player who was behind could win all ko fights, and eventually there would be a ko fight that neither could afford to lose. Too many games would be drawn. It would end up like chess! But removing the superko rule and allowing agreed draws would be an improvement I think. I suppose there is the danger that an obnoxious player could continue the loop until his opponent got bored, but your plan of having a fixed maximum number of moves would sort this out. In fact it's such a good idea that I think I may have suggested here a long time ago. At 17:23 23/10/2006, you wrote: One solution to all of this is to HAVE NO KO RULE! Then all the nonsense goes away. It then comes down to each player having his fate in his own hands.If you want to win, you will avoid cycles, but you are not arbitrarily told what a cycle is or what version of some cycle rule is considered illegal. Indeed, there are no illegal moves in the KO sense. This also greatly simplifies the rules. The KO rule is often the most confusing to beginners with all it's variations and is difficult to state concisely. Imagine being able to do away with it entirely! This gives 3 possible results for all possible games: 1. Black wins 2. White wins 3. Game never completes. I would argue that after an infinite number of moves, a game be considered a draw. Neither side wanted to fight for it or neither side could attain a win - so a draw is the logical conclusion to such a game. This all has great beauty. A game is never decided by a KO side-effect. The responsibility of winning - or even of making progress is put upon the players themselves. From a programmers prospective there are no GHI issues (unless the programmer creates it for practical reasons.) But now we have one itty bitty practical inconvenience. How to you conduct tournaments and matches where games can last forever? Since GO currently has arbitrary KO rules for practical convenience, why not introduce another arbitrary but practical rule to handle this situation?After all, we just got rid of the nuisance KO rule? The rule we could introduce (which can be concisely stated) is to set a move number limit on the game. If a game goes to move N, it is over and a draw is declared. (Or we could award the game to WHITE if we want to make draws impossible.) My guess is that in practical play human players will notice the cycles, and either come to a draw agreement or break the cycle. When programs play, this may not always happen. I argue that the arbitrary game limit is no more arbitrary than rules of KO which we impose for practical reasons only. We could make N be 2 * boardsize. On 9x9 a game is over after 162 plays. It would be 722 for 19x19. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move? Ko
Quoting alain Baeckeroot <[EMAIL PROTECTED]>: It seems this kind of strategic consideration/evaluation is not (yet) part of computer go (and as kyu player, its hardly getting into my game ;) I think the top programs on CGOS handle ko fights very well on 9x9, relative to their strength in general. On 7x7 Valkyria often not only plays the ko fights correctly it also knows that it will win it even before starting it. When I play it I actually see it as a bad sign if a ko fight develops. With my older programs a ko fight was always something I gained from, this is no longer the case. This is a strong benefit of Monte Carlo go approach. There is not a single line of code in Valkyria, that helps it to play ko. It just does it anyway. -Magnus ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move? Ko
Le lundi 23 octobre 2006 22:12, Don Dailey a écrit : > I'm just looking for a way out of the KO ugliness as a mental exercise. arg , ko is not ugly :) A famous go proverb, you can find in the excellent book "go proverbs": "If you are afraid of ko, don't play go." And a strong pro (sorry i forgot who) approximately said: "If life was go game, i would live by ko." > There appears to be no way unless the game is changed significantly. Ko is also a way to manage weaknesses: if one player is solid (and probably seems a bit small), and the other has many weakness (and looks wide), the first one can play move which need ko because he will win it, and so he has more choice for his moves. It seems this kind of strategic consideration/evaluation is not (yet) part of computer go (and as kyu player, its hardly getting into my game ;) Alain > > You could just allow simple KO under the same circumstances of move or > time limited games. > > > - Don > > > On Mon, 2006-10-23 at 22:00 +0200, John Tromp wrote: > > On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote: > > > > > I'm not very good at GO, but I would assume that it would change the > > > game some. But it would be a change that was adjusted to. Knowing how > > > to avoid these situations would be part of a good players strategy. > > > > "Some" is an understatement. It would change the game quite a bit, > > since almost every game features kos, not only in actual play, but also > > in the considerations of both players. > > > > > How bad would it be? Would it create a situation where good players > > > couldn't beat significantly weaker players any longer? > > > > Yes; you can argue about the value of being able to win all kos > > in terms of handicap stones. I think it would be well over 4 stones. > > Being able to invade and create moonshine life is quite a perk. > > > > Could be a fun experiment to put to the test:) > > > > regards, > > -John > > ___ > 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] When is Pass the best move?
I'm just looking for a way out of the KO ugliness as a mental exercise. There appears to be no way unless the game is changed significantly. You could just allow simple KO under the same circumstances of move or time limited games. - Don On Mon, 2006-10-23 at 22:00 +0200, John Tromp wrote: > On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote: > > > I'm not very good at GO, but I would assume that it would change the > > game some. But it would be a change that was adjusted to. Knowing how > > to avoid these situations would be part of a good players strategy. > > "Some" is an understatement. It would change the game quite a bit, > since almost every game features kos, not only in actual play, but also > in the considerations of both players. > > > How bad would it be? Would it create a situation where good players > > couldn't beat significantly weaker players any longer? > > Yes; you can argue about the value of being able to win all kos > in terms of handicap stones. I think it would be well over 4 stones. > Being able to invade and create moonshine life is quite a perk. > > Could be a fun experiment to put to the test:) > > regards, > -John ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote: I'm not very good at GO, but I would assume that it would change the game some. But it would be a change that was adjusted to. Knowing how to avoid these situations would be part of a good players strategy. "Some" is an understatement. It would change the game quite a bit, since almost every game features kos, not only in actual play, but also in the considerations of both players. How bad would it be? Would it create a situation where good players couldn't beat significantly weaker players any longer? Yes; you can argue about the value of being able to win all kos in terms of handicap stones. I think it would be well over 4 stones. Being able to invade and create moonshine life is quite a perk. Could be a fun experiment to put to the test:) regards, -John ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On Mon, 2006-10-23 at 16:01 -0200, Mark Boon wrote: > > On 23-okt-06, at 14:23, Don Dailey wrote: > > > Then all the nonsense goes away. It then comes down to each player > > > > having his fate in his own hands.If you want to win, you will > > avoid > > > > cycles, > > > > That's a rather bizarre proposal. Ko is so common in Go. It would mean > that he who is ahead would have to concede every possible ko, even > some extremely unreasonable ones. In those cases where the game > balances on the ko (which is a high percentage) you'd get a draw. I'm not very good at GO, but I would assume that it would change the game some. But it would be a change that was adjusted to. Knowing how to avoid these situations would be part of a good players strategy. How bad would it be? Would it create a situation where good players couldn't beat significantly weaker players any longer? By the way, I'm not really proposing this. I'm just thinking out loud. - Don > Mark > > ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On 23-okt-06, at 14:23, Don Dailey wrote:Then all the nonsense goes away. It then comes down to each player having his fate in his own hands. If you want to win, you will avoid cycles, That's a rather bizarre proposal. Ko is so common in Go. It would mean that he who is ahead would have to concede every possible ko, even some extremely unreasonable ones. In those cases where the game balances on the ko (which is a high percentage) you'd get a draw. Mark___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
Let me address some of your points directly: > ... > > In Go, the forbidden ko point is another piece of information you could > add, being similar to en-passent capture possibilities in that it is only > about what happened in the last move. > > You may well say "2 identical configuration - one with a forbidden ko > point and one without, are simply NOT the same position." > > But the approach of including bits of information about the past > is inherently flawed since it cannot be taken to its extreme. We cannot > say "it is illegal to repeat an entire history of positions". > > That's why the simplest approach to superko is to include no information > whatsoever, not even turn. But I feel this is taken to the extreme. You can expect the same results from MOST positions that are situationally equivalent - but side to move differences are enormous. Consider for example the opening position. With black to move we expect black to win very handily (without komi.) But if black makes a pass move, the positions are in no sense equivalent.In fact, you don't have to work hard to construct anomalous examples, just about every position in the game, short of the extreme endgame, has a different game theoretic evaluation depending on which side gets to move first. PSK takes this concept of "not bothering to capture a position perfectly" to absurd extremes. It considers positions that are consistently many stones apart in game theoretic value as being the same. The only reason to have a KO rule is to prevent by force, long cycles. So I don't see a point in imposing more restrictive conditions than necessary. Having said that, I see your point about situational super ko. Even in SSK we compare positions that have some details of history NOT in common. So they are indeed different positions in a pure sense. By that definition no positions can ever repeat because they always have a different "modern" history. So even if we wanted to, we can't have an effective game shortening rule that says "identical" positions cannot repeat. SSK is the best we can do in a practical sense. > I don't understand how you can argue that this is more complicated > than considering configuration+turn. > If you consider superko to be the rule that you cannot repeat a STATE of > the game, then what's the simplest possible choice of state? The simplest choice is to consider all positions equivalent - since we have decided that we can be arbitrary about how we define state.But then every move is illegal. But you have chosen a rule which makes more move illegal than necessary because it's "simple", so if you need to play that game, then it's simpler to say all positions are equivalent. You might also consider a rule that says never move to a point that was once inhabited. I think that might be an interesting variant of the game but it's not GO. But since we have decided that a position doesn't have to have all details in common, why not? > I'd argue it's whatever entails the minimum amount of information. > You can't include less information than the board configuration, obviously. But it seems rather arbitrary to make that statement. I guess my answer it that you obviously must include side to move information as a minimum to even consider positions at least "similar", even if you give up on the idea of perfectly identical. > And that by itself is good enough for all practical purposes, as you admit. Not for ALL practical purposes. I think PSK is a poor choice for a solver engine combined with database-like tables.It produces more positions that cannot be resolved cleanly. It produces exceptions that are normally not logical/predictable and it even invalidates Benson life. > And that is why I consider PSK the most logical choice. Yes, you are using the argument that a shorter description makes it superior. You wonder why I consider PSK more complicated. It's more a semantics issue. From my point of view I see a meaningful concept having to be altered - making it more complicated. Perhaps from my many years of chess programming I have never considered a white to move position to be equivalent in any way to a black to move position. To describe this concept in chess terms we have to introduce terms like "triangulation", which is the process of wasting a move in a meaningful way to achieve the same position but with the colors reversed. But PSK is less complicated, as you say, if you consider it from the information complexity point of view. It's just that everything else gets more complicated. Certain moves that wouldn't get dropped now get dropped from the list of legal choices. My last post was almost (but not quite) tongue in cheek about throwing out KO rules completely. It's simpler and more logical that PSK or any of the KO variants, it's just not PRACTICAL unfortunately. It occurred to me that on CGOS, I could eliminate the KO rule entirely an
Re: [computer-go] When is Pass the best move?
On 10/23/06, John Tromp <[EMAIL PROTECTED]> wrote: Who is to say that SSK doesn't lead to similarly bizarre situations?I'm not sure what you would consider bizarre, but the example I posted works the same for SSK.The problem is superko. For all common variants there are (rare) situations where an extreme* outcome is (needlessly) forced upon an otherwise balanced situation. What's even worse is that superko bans can become active without need. IMO the only good reason for a long cycle rule is to prevent infinite games, so therefore it should never interfere with false cycles (which cannot repeat multiple times, or where *only* one side would need an infinite stone supply). If one makes the rule more general than absolutely necessary why stop at PSK? We might just as well say something like "any intersection may only be played once". Erik* illegal move -> any other (legal) move is better -> in the game graph this is equivalent to assigning an immediate maximal loss. Draws, which are typically not an option with superko, are less disturbing. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
One solution to all of this is to HAVE NO KO RULE! Then all the nonsense goes away. It then comes down to each player having his fate in his own hands.If you want to win, you will avoid cycles, but you are not arbitrarily told what a cycle is or what version of some cycle rule is considered illegal. Indeed, there are no illegal moves in the KO sense. This also greatly simplifies the rules. The KO rule is often the most confusing to beginners with all it's variations and is difficult to state concisely. Imagine being able to do away with it entirely! This gives 3 possible results for all possible games: 1. Black wins 2. White wins 3. Game never completes. I would argue that after an infinite number of moves, a game be considered a draw. Neither side wanted to fight for it or neither side could attain a win - so a draw is the logical conclusion to such a game. This all has great beauty. A game is never decided by a KO side-effect. The responsibility of winning - or even of making progress is put upon the players themselves. From a programmers prospective there are no GHI issues (unless the programmer creates it for practical reasons.) But now we have one itty bitty practical inconvenience. How to you conduct tournaments and matches where games can last forever? Since GO currently has arbitrary KO rules for practical convenience, why not introduce another arbitrary but practical rule to handle this situation?After all, we just got rid of the nuisance KO rule? The rule we could introduce (which can be concisely stated) is to set a move number limit on the game. If a game goes to move N, it is over and a draw is declared. (Or we could award the game to WHITE if we want to make draws impossible.) My guess is that in practical play human players will notice the cycles, and either come to a draw agreement or break the cycle. When programs play, this may not always happen. I argue that the arbitrary game limit is no more arbitrary than rules of KO which we impose for practical reasons only. We could make N be 2 * boardsize. On 9x9 a game is over after 162 plays. It would be 722 for 19x19. Ok, let me change CGOS to do it this way now just kidding. - Don On Mon, 2006-10-23 at 16:44 +0200, John Tromp wrote: > On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote: > > > I don't believe in positional superko. I know that 99.9% of the time it > > makes little or no difference, but I don't see how it can be correct. > > 2 identical configuration - each with different color to move are simply > > NOT the same position. > > They are by definition. The other superko rule is called Situational > SuperKo for a reason. It uses the word situation to denote the combination > of position and turn. > > As a chess player, you must be used to the phrase > "in this position, with white to move..." > There also, turn is considered a piece of additional information. > > Turn is just one piece of information about the past that you can add > to position to make you feel it better describes the possible futures. > In chess there are many other such pieces of information, such as > castling rights and possibility of en-passent captures. You may feel > that these are also an inherent part of the position, because they > affect the future. But why stop there? The future also depends on > when 3-fold repetition occurs, so maybe past occurances should > also be included in the notion of position? Clearly, this leads us astray. > > In Go, the forbidden ko point is another piece of information you could > add, being similar to en-passent capture possibilities in that it is only > about what happened in the last move. > > You may well say "2 identical configuration - one with a forbidden ko > point and one without, are simply NOT the same position." > > But the approach of including bits of information about the past > is inherently flawed since it cannot be taken to its extreme. We cannot > say "it is illegal to repeat an entire history of positions". > > That's why the simplest approach to superko is to include no information > whatsoever, not even turn. > I don't understand how you can argue that this is more complicated > than considering configuration+turn. > If you consider superko to be the rule that you cannot repeat a STATE of > the game, then what's the simplest possible choice of state? > I'd argue it's whatever entails the minimum amount of information. > You can't include less information than the board configuration, obviously. > And that by itself is good enough for all practical purposes, as you admit. > > And that is why I consider PSK the most logical choice. > > In my paper on the combinatorics of Go, I discovered that PSK also > leads to the simplest mathematical characterization of a game of go. > The game graph consist of all legal positions (configurations) with edges > between them corresponding to non-pass-moves. A game of Go
Re: [computer-go] When is Pass the best move?
Does anyone have an example where "pass" is the best move, and not part of the two passes to end the game? I'm trying to >determine if passes should ever be considered in a search for the best move, and if so, how to exclude them until it is really >necessary. Which round is first pass move made ever in professional games 19*19 board? I don't remember ever made pass move earlier than 200 moves, or if done those have been bad mouse clicks. Maybe such dumb rule could work that if there is no any other movable position, or movable position counter is less than 5(or y), try out also pass. t. harri ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote: I don't believe in positional superko. I know that 99.9% of the time it makes little or no difference, but I don't see how it can be correct. 2 identical configuration - each with different color to move are simply NOT the same position. They are by definition. The other superko rule is called Situational SuperKo for a reason. It uses the word situation to denote the combination of position and turn. As a chess player, you must be used to the phrase "in this position, with white to move..." There also, turn is considered a piece of additional information. Turn is just one piece of information about the past that you can add to position to make you feel it better describes the possible futures. In chess there are many other such pieces of information, such as castling rights and possibility of en-passent captures. You may feel that these are also an inherent part of the position, because they affect the future. But why stop there? The future also depends on when 3-fold repetition occurs, so maybe past occurances should also be included in the notion of position? Clearly, this leads us astray. In Go, the forbidden ko point is another piece of information you could add, being similar to en-passent capture possibilities in that it is only about what happened in the last move. You may well say "2 identical configuration - one with a forbidden ko point and one without, are simply NOT the same position." But the approach of including bits of information about the past is inherently flawed since it cannot be taken to its extreme. We cannot say "it is illegal to repeat an entire history of positions". That's why the simplest approach to superko is to include no information whatsoever, not even turn. I don't understand how you can argue that this is more complicated than considering configuration+turn. If you consider superko to be the rule that you cannot repeat a STATE of the game, then what's the simplest possible choice of state? I'd argue it's whatever entails the minimum amount of information. You can't include less information than the board configuration, obviously. And that by itself is good enough for all practical purposes, as you admit. And that is why I consider PSK the most logical choice. In my paper on the combinatorics of Go, I discovered that PSK also leads to the simplest mathematical characterization of a game of go. The game graph consist of all legal positions (configurations) with edges between them corresponding to non-pass-moves. A game of Go is precisely a simple path through this graph, starting at the empty node. Using SSK would lead to a far less elegant characterization. Your example may illustrate a problem with superko. It's my belief that superko can create bizarre and anomalous situations like this The occurance of bizarre situations appears to be a very common phenomenon in Go, whether you have PSK or not. Go is such a rich and subtle game that you cannot expect too many rules to hold without their share of exceptions. For instance, a group with 2 "false" eyes can be unconditionally alive in some cases. We may admire this richness rather than view it as something anomalous that needs fixing. Who is to say that SSK doesn't lead to similarly bizarre situations? My guess is that they exist there as well, just harder to find... regards, -John ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
In message <[EMAIL PROTECTED]>, Don Dailey <[EMAIL PROTECTED]> writes When someone mentioned a position where a pass-alive group should be sacrificed - I wondered if it was also due to PSK issues. I want to clarify something I said about PSK. I don't think the rule is "wrong" in any sense - after all you can make up any rules you want as long as they are internally consistent. I just believe it's a rather arbitrary rule which has been accepted primarily because it rarely turns out to make a difference in most situations. PSK has been accepted by KGS because it is what the Chinese rules (as used on KGS for computer Go events) appear to specify. But I suspect that the authors of the Chinese rules never even considered PSK and SSK as alternatives. Personally I prefer NSSK (Natural Situational Superko) to SSK, and SSK to PSK. I think that very few people who understand the difference will prefer PSK. Nick For instance, I could add a rule to chess which says "it's illegal to move a bishop to g2 on the 8th move." It would be a rather silly and arbitrary rule and wouldn't be consistent with the spirit of the game, and it would introduce a small bias against white for no good reason - but it would be a valid rule and the game could still be played reasonably. However it would be an ugly wart on the game. (Chess has a lot of funny rules in it anyway which have been added over the years to improve the game.) - Don On Mon, 2006-10-23 at 11:56 +0200, Erik van der Werf wrote: On 10/23/06, Tom Cooper <[EMAIL PROTECTED]> wrote: > At 01:54 23/10/2006, you wrote: > > >There was a posting on this list with an example of a (contrived?) > >situation where sacrificing a pass-alive group is appropriate, in order to > >win a ko that is more valuable. Is even #1 "100% admissible"? > > > >Weston > > > I must have missed this, and find it surprising. Can anyone remember the > example? > I probably posted that; it is a superko anomaly. . O O # # # O O . O . O # . # O O # O O # . # O O # . # # # # # O O # # O O O O # # O O . . . O # # # # O O O O # # O O O # O O . O # O . O # # O . O # O O . # . 9x9 board, superko, area scoring, 6 komi for White It does not matter who plays first. Assuming that the players agree that white's upper left group is dead the position can be scored as it stands (jigo). Solution at http://www.cs.unimaas.nl/~vanderwerf/pubdown/stelling3.sgf Erik ___ 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/ -- Nick Wedd[EMAIL PROTECTED] ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
When someone mentioned a position where a pass-alive group should be sacrificed - I wondered if it was also due to PSK issues. I want to clarify something I said about PSK. I don't think the rule is "wrong" in any sense - after all you can make up any rules you want as long as they are internally consistent. I just believe it's a rather arbitrary rule which has been accepted primarily because it rarely turns out to make a difference in most situations. For instance, I could add a rule to chess which says "it's illegal to move a bishop to g2 on the 8th move." It would be a rather silly and arbitrary rule and wouldn't be consistent with the spirit of the game, and it would introduce a small bias against white for no good reason - but it would be a valid rule and the game could still be played reasonably. However it would be an ugly wart on the game. (Chess has a lot of funny rules in it anyway which have been added over the years to improve the game.) - Don On Mon, 2006-10-23 at 11:56 +0200, Erik van der Werf wrote: > On 10/23/06, Tom Cooper <[EMAIL PROTECTED]> wrote: > > At 01:54 23/10/2006, you wrote: > > > > >There was a posting on this list with an example of a (contrived?) > > >situation where sacrificing a pass-alive group is appropriate, in > order to > > >win a ko that is more valuable. Is even #1 "100% admissible"? > > > > > >Weston > > > > > > I must have missed this, and find it surprising. Can anyone > remember the > > example? > > > > I probably posted that; it is a superko anomaly. > > > . O O # # # O O . > O . O # . # O O # > O O # . # O O # . > # # # # # O O # # > O O O O # # O O . > . . O # # # # O O > O O # # O O O # O > O . O # O . O # # > O . O # O O . # . > > 9x9 board, superko, area scoring, 6 komi for White > It does not matter who plays first. > > > Assuming that the players agree that white's upper left group is dead > the position can be scored as it stands (jigo). > > Solution at http://www.cs.unimaas.nl/~vanderwerf/pubdown/stelling3.sgf > > Erik > > > > ___ > 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] When is Pass the best move?
On Mon, 2006-10-23 at 11:25 +0200, Erik van der Werf wrote: > On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote: > > ... A region of 7 inside a benson > > group cannot possibly support enemy life. So moves inside > them > > by either color do not improve the position. > > Normally (under traditional Go rules) you would be right that a region > of 7 surrounded by pass-alive stones cannot be invaded successfully. > However, when using positional superko this is *not* true. The reason > is moonshine life. I don't believe in positional superko. I know that 99.9% of the time it makes little or no difference, but I don't see how it can be correct. 2 identical configuration - each with different color to move are simply NOT the same position. However CGOS uses it - it seems to be the most popular rule and so we are stuck with it. But my solver will not use positional superko. I consider positional superko a complication of the rules and it's usually best to keep things pure and simple. Your example may illustrate a problem with superko. It's my belief that superko can create bizarre and anomalous situations like this simply because it adds complexity. Not only are repeated positions illegal, but so are repeated configurations - for no LOGICAL reason that I can think of. I think this rule is a minor wart on the wonderful Tromp/Taylor rules. PSK is bound to creates extra trouble with hash tables too. It makes some positions arbitrarily illegal. - Don > 5x5 recapture at a forbidden due to ko > > O a O # # > . O # . # > O O # # # > # # # . # > # # # # # > > This is also an illustration of why it might make sense to have pass > lift the ko ban. > > > > Right not I'm working on a perfect solver for 5x5 > > cool :-) > > Erik > ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On 10/23/06, Tom Cooper <[EMAIL PROTECTED]> wrote:> At 01:54 23/10/2006, you wrote:> > >There was a posting on this list with an example of a (contrived?) > >situation where sacrificing a pass-alive group is appropriate, in order to> >win a ko that is more valuable. Is even #1 "100% admissible"?> >> >Weston> > > I must have missed this, and find it surprising. Can anyone remember the> example?> I probably posted that; it is a superko anomaly. . O O # # # O O .O . O # . # O O # O O # . # O O # .# # # # # O O # # O O O O # # O O .. . O # # # # O O O O # # O O O # OO . O # O . O # # O . O # O O . # .9x9 board, superko, area scoring, 6 komi for WhiteIt does not matter who plays first.Assuming that the players agree that white's upper left group is dead the position can be scored as it stands (jigo). Solution at http://www.cs.unimaas.nl/~vanderwerf/pubdown/stelling3.sgfErik ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
On 10/23/06, Don Dailey <[EMAIL PROTECTED]> wrote:> ... A region of 7 inside a benson> group cannot possibly support enemy life. So moves inside them> by either color do not improve the position. Normally (under traditional Go rules) you would be right that a region of 7 surrounded by pass-alive stones cannot be invaded successfully. However, when using positional superko this is *not* true. The reason is moonshine life. 5x5 recapture at a forbidden due to koO a O # # . O # . #O O # # # # # # . ## # # # # This is also an illustration of why it might make sense to have pass lift the ko ban.> Right not I'm working on a perfect solver for 5x5 cool :-)Erik ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
At 01:54 23/10/2006, you wrote: There was a posting on this list with an example of a (contrived?) situation where sacrificing a pass-alive group is appropriate, in order to win a ko that is more valuable. Is even #1 "100% admissible"? Weston I must have missed this, and find it surprising. Can anyone remember the example? ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
Section 6 in http://lie.math.brocku.ca/twolf/papers/mono.pdf is about chains with a single eye who's status is ko (the original position does not have a ko-forbidden field) and where passing is one of the best moves of both sides. There also is a position at the end of the paper where the first two! moves are passes. Thomas On Sun, 22 Oct 2006, Phil G wrote: > Does anyone have an example where "pass" is the best move, and not part of > the two passes to end the game? I'm trying to determine if passes should ever > be considered in a search for the best move, and if so, how to exclude them > until it is really necessary. Thanks, Phil ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
There was a posting on this list with an example of a (contrived?) situation where sacrificing a pass-alive group is appropriate, in order to win a ko that is more valuable. Is even #1 "100% admissible"? WestonOn 10/22/06, Don Dailey <[EMAIL PROTECTED]> wrote: I'm in a similar situation, I'm trying to identify classes of movesthat I can eliminate in an admissible way - which means the move I amthrowing out is either not the best move, or there are other equallygood moves. I know that pass moves can be the best move in seki situations - andit's non-trivial how to identify them.I'm not good at go and this is a severe handicap for me, but here iswhat I come up with so far - please add to my list if you know of anything else: 1. Benson space - I use benson's algorithm to find pass-alive groups and if a small "region" is enclosed completely by benson groups, there is never a point moving inside of them for either color (except in cleanup situations for Chinese rules) A "region" is defined as strings of points that can consist of any combination of enemy stones and empty intersections. A large region can exist inside benson safe groups that allows for life - so care must be taken that you identify the correct regions. I don't know if I'm doing it the most efficient way, but I'm going by region size. A region of 7 inside a benson group cannot possibly support enemy life. So moves inside them by either color do not improve the position. 2. I have a quick and dirty pass rule - I throw out all pass moves in the early part of the game. I can't prove this rule is admissible but I feel very safe with a rule like, "don't allow pass if half the points on the board are empty." I feel you can probably be a lot less conservative - but if anyone knows a way to identify when to start including pass moves in a search in a theoretically sound way - I'm all ears! 3. Unfortunately, the eye-filling rule is not admissible other than in benson situations. The eye-filling rule I use has been described on this group - don't move to a point surrounded on all sides by stones of the same color - where the opponent doesn't occupy more than 1 diagonal (different if on edge of board.) I may or may not use this rule depending on what I'm trying to do. 4. Don't move to any of the corner points on the first move.Right not I'm working on a perfect solver for 5x5 - and rule 1 and 2 arethe only rules I know that are 100% admissible. I suspect rules 2 and 4 are admissible - at least on 5x5 or larger although I cannot back thatup with any theory.Rule 4, the corner rule can probably be generalized - and I think that'swhat a good pattern database might be able to do.I would like to be able to build an admissible pattern database of the form that veto'sspecific moves.But the database must be provably correct, not builtbased on a humans intuition that a move is "probably" not good. So I'm basically lost here. my solver is just a step towards the goalof a pattern database that can admissibly remove many pointless movesfrom a tree search.- DonOn Sun, 2006-10-22 at 10:47 -0700, Phil G wrote: > Does anyone have an example where "pass" is the best move, and not> part of the two passes to end the game? I'm trying to determine if> passes should ever be considered in a search for the best move, and if > so, how to exclude them until it is really necessary. Thanks, Phil> ___ > computer-go mailing list> computer-go@computer-go.org> http://www.computer-go.org/mailman/listinfo/computer-go/ ___computer-go mailing listcomputer-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] When is Pass the best move?
During the main search, pass is always one of the moves searched, and if is the best move found, and pass is allowed, it will play a pass. I never avoid searching "pass" in the main search since it gives a good lower bound on the score. If the search returns "pass" too early, I'll play the second best move instead. Many Faces of Go uses the following rules: - pass is always allowed if the opponent passed on the previous move otherwise - pass is allowed if the move number is at least half the board size (181 on a full size board) and the pass search found no good moves for the opponent. Before I do the main search for the color to move, I do a pass search for the opponent, to find good opponent moves if the color to move passes. These moves are searched early in the main search. I'm trying to find killer moves early. David > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Don Dailey > Sent: Sunday, October 22, 2006 5:08 PM > To: computer-go > Subject: Re: [computer-go] When is Pass the best move? > > > I'm in a similar situation, I'm trying to identify classes > of moves that I can eliminate in an admissible way - which > means the move I am throwing out is either not the best move, > or there are other equally good moves. > > I know that pass moves can be the best move in seki situations - and > it's non-trivial how to identify them. > > I'm not good at go and this is a severe handicap for me, but > here is what I come up with so far - please add to my list if > you know of anything else: > > 1. Benson space - I use benson's algorithm to find > pass-alive groups > and if a small "region" is enclosed completely by benson > groups, there is never a point moving inside of them for either > color (except in cleanup situations for Chinese rules) > > A "region" is defined as strings of points that can consist of > any combination of enemy stones and empty intersections. > > A large region can exist inside benson safe groups that allows > for life - so care must be taken that you identify the correct > regions. I don't know if I'm doing it the most efficient way, > but I'm going by region size. A region of 7 inside a benson > group cannot possibly support enemy life. So moves inside them > by either color do not improve the position. > >2. I have a quick and dirty pass rule - I throw out all pass moves > in the early part of the game. I can't prove this rule is > admissible but I feel very safe with a rule like, "don't allow > pass if half the points on the board are empty." > > I feel you can probably be a lot less conservative - > but if anyone > knows a way to identify when to start including pass moves in a > search in a theoretically sound way - I'm all ears! > >3. Unfortunately, the eye-filling rule is not admissible other than > in benson situations. The eye-filling rule I use has been > described on this group - don't move to a point surrounded on > all sides by stones of the same color - where the opponent > doesn't occupy more than 1 diagonal (different if on edge of > board.) I may or may not use this rule depending on what I'm > trying to do. > >4. Don't move to any of the corner points on the first move. > > > Right not I'm working on a perfect solver for 5x5 - and rule > 1 and 2 are > the only rules I know that are 100% admissible. I suspect > rules 2 and > 4 are admissible - at least on 5x5 or larger although I > cannot back that > up with any theory. > > Rule 4, the corner rule can probably be generalized - and I > think that's > what a good pattern database might be able to do.I would > like to be > able to build an admissible pattern database of the form that veto's > specific moves.But the database must be provably correct, > not built > based on a humans intuition that a move is "probably" not good. > > So I'm basically lost here. my solver is just a step > towards the goal > of a pattern database that can admissibly remove many > pointless moves from a tree search. > > > - Don > > > > > > On Sun, 2006-10-22 at 10:47 -0700, Phil G wrote: > > Does anyone have an example where "pass" is the best move, and not > > part of the two passes to end the game? I'm trying to determine if > > passes should ever be considered in a search for the best >
[computer-go] When is Pass the best move?
Does anyone have an example where "pass" is the best move, and not part of the two passes to end the game? I'm trying to determine if passes should ever be considered in a search for the best move, and if so, how to exclude them until it is really necessary. Thanks, Phil ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] When is Pass the best move?
I'm in a similar situation, I'm trying to identify classes of moves that I can eliminate in an admissible way - which means the move I am throwing out is either not the best move, or there are other equally good moves. I know that pass moves can be the best move in seki situations - and it's non-trivial how to identify them. I'm not good at go and this is a severe handicap for me, but here is what I come up with so far - please add to my list if you know of anything else: 1. Benson space - I use benson's algorithm to find pass-alive groups and if a small "region" is enclosed completely by benson groups, there is never a point moving inside of them for either color (except in cleanup situations for Chinese rules) A "region" is defined as strings of points that can consist of any combination of enemy stones and empty intersections. A large region can exist inside benson safe groups that allows for life - so care must be taken that you identify the correct regions. I don't know if I'm doing it the most efficient way, but I'm going by region size. A region of 7 inside a benson group cannot possibly support enemy life. So moves inside them by either color do not improve the position. 2. I have a quick and dirty pass rule - I throw out all pass moves in the early part of the game. I can't prove this rule is admissible but I feel very safe with a rule like, "don't allow pass if half the points on the board are empty." I feel you can probably be a lot less conservative - but if anyone knows a way to identify when to start including pass moves in a search in a theoretically sound way - I'm all ears! 3. Unfortunately, the eye-filling rule is not admissible other than in benson situations. The eye-filling rule I use has been described on this group - don't move to a point surrounded on all sides by stones of the same color - where the opponent doesn't occupy more than 1 diagonal (different if on edge of board.) I may or may not use this rule depending on what I'm trying to do. 4. Don't move to any of the corner points on the first move. Right not I'm working on a perfect solver for 5x5 - and rule 1 and 2 are the only rules I know that are 100% admissible. I suspect rules 2 and 4 are admissible - at least on 5x5 or larger although I cannot back that up with any theory. Rule 4, the corner rule can probably be generalized - and I think that's what a good pattern database might be able to do.I would like to be able to build an admissible pattern database of the form that veto's specific moves.But the database must be provably correct, not built based on a humans intuition that a move is "probably" not good. So I'm basically lost here. my solver is just a step towards the goal of a pattern database that can admissibly remove many pointless moves from a tree search. - Don On Sun, 2006-10-22 at 10:47 -0700, Phil G wrote: > Does anyone have an example where "pass" is the best move, and not > part of the two passes to end the game? I'm trying to determine if > passes should ever be considered in a search for the best move, and if > so, how to exclude them until it is really necessary. > > > > Thanks, > > > > Phil > > > > > ___ > 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/
