Where to play at the end of the Fuseki (practical example)?
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Kirby
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Re: Where to play at the end of the Fuseki (practical exampl
Agree. This topic is a bit funny because a concept like "thickness" can mean different things depending on the skill level of the player. At KGS 1d, I would call it thick. Apparently, KGS 4~5d thinks so, too. Does a pro think it's thick? I don't know. But maybe it doesn't matter if you don't understand the reasoning and sequences behind the pro's thinking.
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daal
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Re: Where to play at the end of the Fuseki (practical exampl
Indeed, an opponents position is weak only to the extent that you as a player can do something worthwhile against it. Nonetheless, the perspective that the strength of a position might turn out to be an illusion is valuable, as it encourages you to look for weaknesses and try to take advantage of them instead of just assuming that something is strong.Kirby wrote:Agree. This topic is a bit funny because a concept like "thickness" can mean different things depending on the skill level of the player. At KGS 1d, I would call it thick. Apparently, KGS 4~5d thinks so, too. Does a pro think it's thick? I don't know. But maybe it doesn't matter if you don't understand the reasoning and sequences behind the pro's thinking.
Patience, grasshopper.
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John Fairbairn
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Re: Where to play at the end of the Fuseki (practical exampl
There is one prominent portion of my very first post on this thread that no-one except for daal seems to have taken into account. I repeat:Indeed, an opponents position is weak only to the extent that you as a player can do something worthwhile against it. Nonetheless, the perspective that the strength of a position might turn out to be an illusion is valuable, as it encourages you to look for weaknesses and try to take advantage of them instead of just assuming that something is strong.
By virtue of inputting so many games in the GoGoD database I probably see a lot more pro games than most people. Most of these have pros' comments which I usually skim through as I input. So my realisation is well grounded, even if I personally have not acquired the understanding yet to explain their reasoning or the skills to back up whatever understanding I have acquired.I am also influenced in my opinion by a growing realisation that pros see weak groups much earlier than I do. To some extent that must be because they have far more terrifying weapons than I do, and so can go after lions where I can only go after rabbits, but I think also a big part of the reason is that we amateurs tend to think of weak groups as anaemic, weedy clusters that have to live urgently, whereas pros seem to count many groups that allow a powerful forcing move (as is the case here) as weak.
I have also introduced a couple of pro examples from books. Nobody has shot them down. Fundamental to my argument is the belief that pros know more than amateurs about go. What I am hearing here is simply "I (amateur X) call this thickness". I am querying these assertions on two grounds. One is that it seems clear to me that two kinds of thickness that belong to different parts of the game are being mixed up. On that I'm pretty certain. The other is my just-mentioned growing realisation that thick looking shapes are often not really thick. In this particular case I am not certain whether that is the case or not, hence my original query. I have not yet heard any reason to convince me the iceberg here really is thick as in go or just dense as in real life. Equally, I can't prove it is not thick. I'm not a pro. But I do like to think I have listened to the pros and have learned at least that illusions happen.
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John Fairbairn
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Re: Where to play at the end of the Fuseki (practical exampl
I'll say a little more as a way of extending my coffee-break. First let me repeat the OP position.
Second, let me say there is a relevant brand-new book by Kobayashi Satoru, who would belong in any Hall of Fame for go writers. It is called "Why you will be able to win at go if you stop being envious." The envy/jealousy in question is yakimochi in Japanese, which also means a toasted rice cake. Kobayashi lists, in Little Red Book fashion, the "Five Envies". There are more, but he limits his book to five.
The envy he is talking about is the kind where you look at the board and see only the opponent's big territory. Your only thought then is to demolish it. Example: the black lower side here.
Kobayashi says this very common feeling resolves into some easily identifiable patterns, such as his five envies. In this book these are:
1. Invading into too narrow a space
2. Invading or reducing too deeply.
3. Invading without due regard to the status of your own group
4. Going too close to thickness
5. Being over-concerned with small groups
Now it seems to me that we have to consider whether some of us have our eyes only on the rice cakes here. E.g. do envies 1 to 3 apply?
Invasion at 'a' can be questioned as being into narrow a space, invading too deeply, and driving without due care and attention: envies 1 to 3.
Reductions at b and c, and especially c, can be questioned on the grounds of being too deep a reduction - envy 2. It seems to have been taken for granted that Black will answer at 'd'. Why? He might have a move around 'e'. It seems to me that one of two things can then be expected. Either Black will separate White on the right side (and then how silly does the "thick" ugly blob look?), or White can try to connect to his blob (using his "thickness" to defend not to attack), but Black will sacrifice his 'e' stone to defend his lower side in sente, and so get to the left side first. There is in fact a not dissimilar example of capping the reducing play in Kobayashi's book.
Kobayashi says the solution to the envy problem is quite simple. It is to take a moment to think before each move and look at the whole board to assess which is really the biggest area. Here, there seems to be a good case for asking, "Oops, should I really be looking at the left side first?"
It amused me that I had Kobayashi's advice to take a little time to think fresh in my mind when I started browsing through an even newer book, "How Cho Hun-hyeon thinks" (which is autobiographical despite the title). He divides the book into ten "dan" sections which essentially constitute a Daoist-like progress to enlightenment. It is a course in thinking (his preface talks about learning the power of thinking from the go board), which starts with 1-dan as accepting the need to think, then going on to learning to trust the results of your thinking, investigating thoroughly when you are stuck, and so on, until we get to 8-dan: "Learn from others," 9-dan: "Seeking a balance between mind and body" and then, ta-da, 10-dan: "Make time to think."
PS After posting the above, I went into Sensei's Library and by chance saw the latest posting there was about "weak groups". It seemed to me the definition there was weak. It was actually a definition of floating groups. In Japanese at least, a weak group is one that is "not strong", which includes the possibility that it is fundamentally safe but can be bullied (i.e. giving up free points to the opponent). If some comments about weak groups above are based on the SL notion, then I see some of us are even further apart than I imagined.
Second, let me say there is a relevant brand-new book by Kobayashi Satoru, who would belong in any Hall of Fame for go writers. It is called "Why you will be able to win at go if you stop being envious." The envy/jealousy in question is yakimochi in Japanese, which also means a toasted rice cake. Kobayashi lists, in Little Red Book fashion, the "Five Envies". There are more, but he limits his book to five.
The envy he is talking about is the kind where you look at the board and see only the opponent's big territory. Your only thought then is to demolish it. Example: the black lower side here.
Kobayashi says this very common feeling resolves into some easily identifiable patterns, such as his five envies. In this book these are:
1. Invading into too narrow a space
2. Invading or reducing too deeply.
3. Invading without due regard to the status of your own group
4. Going too close to thickness
5. Being over-concerned with small groups
Now it seems to me that we have to consider whether some of us have our eyes only on the rice cakes here. E.g. do envies 1 to 3 apply?
Invasion at 'a' can be questioned as being into narrow a space, invading too deeply, and driving without due care and attention: envies 1 to 3.
Reductions at b and c, and especially c, can be questioned on the grounds of being too deep a reduction - envy 2. It seems to have been taken for granted that Black will answer at 'd'. Why? He might have a move around 'e'. It seems to me that one of two things can then be expected. Either Black will separate White on the right side (and then how silly does the "thick" ugly blob look?), or White can try to connect to his blob (using his "thickness" to defend not to attack), but Black will sacrifice his 'e' stone to defend his lower side in sente, and so get to the left side first. There is in fact a not dissimilar example of capping the reducing play in Kobayashi's book.
Kobayashi says the solution to the envy problem is quite simple. It is to take a moment to think before each move and look at the whole board to assess which is really the biggest area. Here, there seems to be a good case for asking, "Oops, should I really be looking at the left side first?"
It amused me that I had Kobayashi's advice to take a little time to think fresh in my mind when I started browsing through an even newer book, "How Cho Hun-hyeon thinks" (which is autobiographical despite the title). He divides the book into ten "dan" sections which essentially constitute a Daoist-like progress to enlightenment. It is a course in thinking (his preface talks about learning the power of thinking from the go board), which starts with 1-dan as accepting the need to think, then going on to learning to trust the results of your thinking, investigating thoroughly when you are stuck, and so on, until we get to 8-dan: "Learn from others," 9-dan: "Seeking a balance between mind and body" and then, ta-da, 10-dan: "Make time to think."
PS After posting the above, I went into Sensei's Library and by chance saw the latest posting there was about "weak groups". It seemed to me the definition there was weak. It was actually a definition of floating groups. In Japanese at least, a weak group is one that is "not strong", which includes the possibility that it is fundamentally safe but can be bullied (i.e. giving up free points to the opponent). If some comments about weak groups above are based on the SL notion, then I see some of us are even further apart than I imagined.
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Uberdude
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Re: Where to play at the end of the Fuseki (practical exampl
I think John might be seeing more difference of opinion (in terms of judging the board position rather than vocabulary) between him and me than I do because I use the English word "thick" differently to him. When I used it in this position I use it to mean the solid connected-ness (Robert Jasiek probably has some related clumsy-sounding term) and lack of forcing moves (such as those net peeps of John's example). So neither atsumi nor atsusa. i don't know how similar this is to other English-speaking Go payers. Other times my usage of it might be closer, for example in a whole board position if I say "Black is thick" to mean he has strong groups without weakness so can fight/invade etc with ease. Maybe I can make clear my (mis?)use of the word thick by saying in the below position white's group is both thick and dead. It's not strong. Before it was strong-enough-for-now.
Anyway, trying to convert this white group into a single word might generate a long forum thread, but I don't think it's terribly useful for playing Go. My thoughts when judging that group would be more like: "White has a solid group with a ponnuki facing the centre, but it is squashed up against a black wall above (which is making a rather overconcentrated territory) and has no space for an extension below. It doesn't have 2 clear eyes/eyespce yet and is not going to make much territory. Black's extension there does have some small thinness though together with the shimari so maybe the 2nd line probe underneath could be useful, for example one future aim could be a sequence like below (black of course has other ways to answer and this isn't spectacular for white, but does show one way white could make some use of this group). I also look at possible weaknesses in black's position above that could be useful. for example a or the cut above, and there is maybe some fancy endgame miai thing at b but probably not until/unless the corner is stronger. As for the centre facing ponnuki, it's not an eye yet but black is unlikely to falsify it but plonking in a stone with only 2 liberties, but the angle-points at c might be fun later. As for white maybe he can jump out 2 spaces to d which is a little thin so depending on situations maybe just a one point. Also jumping with the small or big knight's move might also work and could be richer in eyeshape and harder to peep. As for the right edge there's an eye in gote there, or moves like e-g..."
As for John's point about pros seeing weak groups earlier than he or other amateurs do, I think that could be true, and they will certainly see weaknesses that we may not. But they might also see skillful defences we do not too. I have certainly had some games of mine reviewed by pros in which I defended a weak group and they said I shouldn't as it wasn't that weak really, or the opponent could not profit so much from attacking. (Of course I've also had cases I should have defended a weak group but didn't). Sometimes the suggested tenuki is not so much of a tenuki in that it is a move which pre-emptively takes away the profit they would have made from attacking. I've noticed such a style of leaving weakish groups that are hard to profit by attacking tends to be quite common among the ~5d amateur Chinese who turn up in the UK from time to time. Sometimes I think if 2 pros took over my colour would be in a good position and my pro would take down a group or otherwise get enough profit, but in others my thickness is just not so good and I have a bad position. But in both cases when I play it requires an awful lot of concentration and absence of mistakes to convert that thickness to profit, so I lose quite a lot of that first category as well as the second.
One other thing that I noticed I had a habit of doing (I think I have somewhat corrected it) was making overly honte net capture of a cutting stone in some big wall I would make after my opponent invaded and took some territory. Often being gote was a problem: I thought I was being "professional" and playing honte, but actually it was slow. I say "actually" with a little caution because maybe my reviewer was wrong (or it not wrong, the position was not so clear cut). Probably quite a few of those reviews were from Guo Juan 5p, who is undoubtedly very strong, but not a top pro (though does admit when she doesn't know some things), though I think some others were from Matthew Macfadyen 6d who probably has a rather overplayish and not honte-when-you-should style. Anyway the point I took away from these sort of positions is I didn't need to defend against some cutting stone plastered against my big wall from running away when such running would start a hugely advantageous fight for me. Of course as the board develops the balance of the fight might change and I might need to come back later.
Anyway, does anyone have a pro friend they can ask about this position?
Anyway, trying to convert this white group into a single word might generate a long forum thread, but I don't think it's terribly useful for playing Go. My thoughts when judging that group would be more like: "White has a solid group with a ponnuki facing the centre, but it is squashed up against a black wall above (which is making a rather overconcentrated territory) and has no space for an extension below. It doesn't have 2 clear eyes/eyespce yet and is not going to make much territory. Black's extension there does have some small thinness though together with the shimari so maybe the 2nd line probe underneath could be useful, for example one future aim could be a sequence like below (black of course has other ways to answer and this isn't spectacular for white, but does show one way white could make some use of this group). I also look at possible weaknesses in black's position above that could be useful. for example a or the cut above, and there is maybe some fancy endgame miai thing at b but probably not until/unless the corner is stronger. As for the centre facing ponnuki, it's not an eye yet but black is unlikely to falsify it but plonking in a stone with only 2 liberties, but the angle-points at c might be fun later. As for white maybe he can jump out 2 spaces to d which is a little thin so depending on situations maybe just a one point. Also jumping with the small or big knight's move might also work and could be richer in eyeshape and harder to peep. As for the right edge there's an eye in gote there, or moves like e-g..."
As for John's point about pros seeing weak groups earlier than he or other amateurs do, I think that could be true, and they will certainly see weaknesses that we may not. But they might also see skillful defences we do not too. I have certainly had some games of mine reviewed by pros in which I defended a weak group and they said I shouldn't as it wasn't that weak really, or the opponent could not profit so much from attacking. (Of course I've also had cases I should have defended a weak group but didn't). Sometimes the suggested tenuki is not so much of a tenuki in that it is a move which pre-emptively takes away the profit they would have made from attacking. I've noticed such a style of leaving weakish groups that are hard to profit by attacking tends to be quite common among the ~5d amateur Chinese who turn up in the UK from time to time. Sometimes I think if 2 pros took over my colour would be in a good position and my pro would take down a group or otherwise get enough profit, but in others my thickness is just not so good and I have a bad position. But in both cases when I play it requires an awful lot of concentration and absence of mistakes to convert that thickness to profit, so I lose quite a lot of that first category as well as the second.
One other thing that I noticed I had a habit of doing (I think I have somewhat corrected it) was making overly honte net capture of a cutting stone in some big wall I would make after my opponent invaded and took some territory. Often being gote was a problem: I thought I was being "professional" and playing honte, but actually it was slow. I say "actually" with a little caution because maybe my reviewer was wrong (or it not wrong, the position was not so clear cut). Probably quite a few of those reviews were from Guo Juan 5p, who is undoubtedly very strong, but not a top pro (though does admit when she doesn't know some things), though I think some others were from Matthew Macfadyen 6d who probably has a rather overplayish and not honte-when-you-should style. Anyway the point I took away from these sort of positions is I didn't need to defend against some cutting stone plastered against my big wall from running away when such running would start a hugely advantageous fight for me. Of course as the board develops the balance of the fight might change and I might need to come back later.
Anyway, does anyone have a pro friend they can ask about this position?
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John Fairbairn
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Re: Where to play at the end of the Fuseki (practical exampl
Andrew, useful comments, thank you.
Some points:
1. I find the kind of argument that there may be good defences we can't see not very useful in practice, especially in a game of imperfect information where we have to make judgements while moving forward. In the cases you mention in your games I think I'd make the argument that I played a move that possibly cost a couple of points to avoid a move that might cost a whole group - a necessary compromise in a case where I had to do something. The true answer to being shown a defence is not to change one's understanding of strategies but simply to learn to read deeper.
2. Yes, I had the impression that people here were using thick to mean something more like "safe". My paradigm would be something like:
- a group that has or can almost guarantee two eyes is safe but not necessarily strong (e.g. if it can be bullied)
- a group that cannot be bullied is strong (or solid) but not necessarily thick (e.g. if it has no real function as thickness)
- a group that is thick is one that can function dynamically/strategically as thickness, but that can vary between the opening and middle game (atsumi/atsumi). In the endgame we talk about moves being thick rather than groups.
If you use thick in a way that works for you, obviously that's a good reason to stick with it, but it does seem to me to have at least two drawbacks. One is that you run the risk (admittedly probably small for a high dan player) of not properly appreciating pro advice, or even proverbs and, more importantly, possibly misleading people you teach who read the standard (Japanese-based) literature.
3. For the avoidance of doubt, in the game in question I regard the White blob as safe but hesitate to call it strong simply because it may be potentially weak. As an example, if White plays the sort of shimari attachment you mention, I could conceive of Black answering on the outside in such a way that the White blob can no longer force an eye on the edge. I don't regard it as truly thick (atsui) because I can't yet see how it will end up working as thickness, except by accident. Offensive strategy can't really be based on possible accidents.
4. Your point about the Black group at the top being overconcentrated: That was my first impression, and the impression has certainly not faded completely, but I began to wonder. If you take the NE quadrant alone, and assume the ponnuki shape really was a ponnuki, Black has used 11 stones to White's 12. But he clearly has more territory than White, and since he almost certainly has forcing moves against White there, he can claim to have more thickness (it can function as thickness on the upper side). So the net profit of an extra move, more territory, and surely more forcing moves and more useful thickness, seems to argue for considerable satisfaction for Black. If so, can we really talk about overconcentration? I must admit something feels not quite right about that but I can't put my finger on it.
Some points:
1. I find the kind of argument that there may be good defences we can't see not very useful in practice, especially in a game of imperfect information where we have to make judgements while moving forward. In the cases you mention in your games I think I'd make the argument that I played a move that possibly cost a couple of points to avoid a move that might cost a whole group - a necessary compromise in a case where I had to do something. The true answer to being shown a defence is not to change one's understanding of strategies but simply to learn to read deeper.
2. Yes, I had the impression that people here were using thick to mean something more like "safe". My paradigm would be something like:
- a group that has or can almost guarantee two eyes is safe but not necessarily strong (e.g. if it can be bullied)
- a group that cannot be bullied is strong (or solid) but not necessarily thick (e.g. if it has no real function as thickness)
- a group that is thick is one that can function dynamically/strategically as thickness, but that can vary between the opening and middle game (atsumi/atsumi). In the endgame we talk about moves being thick rather than groups.
If you use thick in a way that works for you, obviously that's a good reason to stick with it, but it does seem to me to have at least two drawbacks. One is that you run the risk (admittedly probably small for a high dan player) of not properly appreciating pro advice, or even proverbs and, more importantly, possibly misleading people you teach who read the standard (Japanese-based) literature.
3. For the avoidance of doubt, in the game in question I regard the White blob as safe but hesitate to call it strong simply because it may be potentially weak. As an example, if White plays the sort of shimari attachment you mention, I could conceive of Black answering on the outside in such a way that the White blob can no longer force an eye on the edge. I don't regard it as truly thick (atsui) because I can't yet see how it will end up working as thickness, except by accident. Offensive strategy can't really be based on possible accidents.
4. Your point about the Black group at the top being overconcentrated: That was my first impression, and the impression has certainly not faded completely, but I began to wonder. If you take the NE quadrant alone, and assume the ponnuki shape really was a ponnuki, Black has used 11 stones to White's 12. But he clearly has more territory than White, and since he almost certainly has forcing moves against White there, he can claim to have more thickness (it can function as thickness on the upper side). So the net profit of an extra move, more territory, and surely more forcing moves and more useful thickness, seems to argue for considerable satisfaction for Black. If so, can we really talk about overconcentration? I must admit something feels not quite right about that but I can't put my finger on it.
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Knotwilg
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Re: Where to play at the end of the Fuseki (practical exampl
When I look at the position in the posted game, or at the one borrowed from Relentless, I see similar groups in similar conditions. Are they strong? Yes. Can they be bullied? Yes, but it requires a great deal of effort by Black. Should you play close to them? Probably not, because such moves won't be efficient. Is it called "thickness"? The position in Relentless is called thickness by Younggil An. The one in the game is not called thickness by John, because it can be bullied. It seems that this pro and John have different definitions, or perhaps the positions are not as similar as I think they are.
For me it doesn't matter too much what "thickness" is. What matters is knowing how to play. And you shouldn't play close to thickness, but use it to attack a group in the vicinity and drive it towards your thickness, or play in a remote area so that the opponent cannot make your strength there overlap with your thickness, etc etc ...
In the Relentless game, eventually White's group was bullied and forced to make life by playing close by. It was perhaps a bit weaker eventually then it seemed at the start. But it had served the purpose of White being able to attack or play elsewhere.
In this game, the group doesn't need immediate reinforcement. To suggest that a reduction at the angle point could be countered by a splitting attack, is beyond me. At most the reduction, when answered, is mildly overlapping with the white strength. Probably an invasion of the lower side is a form of greed, but only because White doesn't need it. The left side is the big one, and the only reason not to play there is that it's hard to find the best move.
For me it doesn't matter too much what "thickness" is. What matters is knowing how to play. And you shouldn't play close to thickness, but use it to attack a group in the vicinity and drive it towards your thickness, or play in a remote area so that the opponent cannot make your strength there overlap with your thickness, etc etc ...
In the Relentless game, eventually White's group was bullied and forced to make life by playing close by. It was perhaps a bit weaker eventually then it seemed at the start. But it had served the purpose of White being able to attack or play elsewhere.
In this game, the group doesn't need immediate reinforcement. To suggest that a reduction at the angle point could be countered by a splitting attack, is beyond me. At most the reduction, when answered, is mildly overlapping with the white strength. Probably an invasion of the lower side is a form of greed, but only because White doesn't need it. The left side is the big one, and the only reason not to play there is that it's hard to find the best move.
Last edited by Knotwilg on Sat Oct 08, 2016 9:13 am, edited 1 time in total.
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Bill Spight
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Re: Where to play at the end of the Fuseki (practical exampl
In the FWIW department, my assessment agrees almost exactly with Crazy Stone's. White has almost picked up komi. I lean towards "c", but have a hard time choosing among it and "a" and "b". "d" was off my radar.dfan wrote:Now that lots of people have weighed in, I gave the position to Crazy Stone for fun (2 million playouts). Its top choices are listed in alphabetical order (that is, it thinks a is best), but all four are very close in evaluation. It assesses the current position as approximately W+5.5 (assuming 7.5 komi).
Please note that my assessment depends upon the thickness of White's right side group. If I assessed it as weak, I would think that Black had the edge.
The Adkins Principle:
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At some point, doesn't thinking have to go on?
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Visualize whirled peas.
Everything with love. Stay safe.
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Kirby
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Re: Where to play at the end of the Fuseki (practical exampl
I don't argue with either of these points, and in fact, since we have evidence that a pro has said those examples were not thick, I'm willing to assume they probably have some insight (though, in fact, the examples don't seem as thick as the position in the OP to me).John Fairbairn wrote: I have also introduced a couple of pro examples from books. Nobody has shot them down. Fundamental to my argument is the belief that pros know more than amateurs about go.
What bothers me about this argument is the implication that, because John saw such examples and has looked at pro games, it gives qualification to make statements about other shapes that may in fact be totally different.
Just because a pro called a shape you considered thick to be thin doesn't mean it extends to other examples. It's not a logical argument.
We don't have pro input here, so claiming to know what a pro thinks about the situation is preemptive. We do have input from some relatively strong amateur dan players who consider the group thick, which is a better argument than something hypothetical.
be immersed
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John Fairbairn
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Re: Where to play at the end of the Fuseki (practical exampl
Kirby, your personal animus against me is becoming rather tiresome, for others as well as myself, I'm sure. Try and find some other way of masturbating in public.
As far as I am concerned it is not an argument. It is an attempt to learn something - a discussion. As a strong dan player myself I can contribute to the discussion at its present level. I also have insight into the pro literature, which I hope helps the discussion. I don't see any useful contributions from you.
As far as I am concerned it is not an argument. It is an attempt to learn something - a discussion. As a strong dan player myself I can contribute to the discussion at its present level. I also have insight into the pro literature, which I hope helps the discussion. I don't see any useful contributions from you.
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Bill Spight
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Re: Where to play at the end of the Fuseki (practical exampl
Possible omission number (Tajima and Sanechika)
The possible omission number (PON) is related to the strength or weakness of a group. A PON of 0 means that the group is unsettled; the attacker to play can kill, the defender to play can live. A PON of 1 means that the attacker to play can move to a position with a PON of 0. I have observed that in the opening pros generally try to make groups with a PON of at least 2.
Tajima and Sanechika have an algorithm for estimating the PON. It has not been, in my view, scientifically verified, but I thought that it would be fun to try to apply it to the White group.
"a" - to "d" represent the first to fourth order dame of the group. Note that the dame that get too close to opposing stones are not counted. To estimate the PON we use them to derive a weighted sum and then take a function of that sum.
There are 11 first order dame with no special significance. They each have a weight of 1, yielding a partial sum of 11.
There are 9 second order dame with no special significance. They have an initial weight of 1. There are 2 second order dame on the edge, which get an initial weight of 1.6, because of eye potential. There are 2 second order dame which are adjacent to a
stone, which get a low initial weight of 0.2, because of that. The second order partial sum is thus 12.6, which has an overall weight of 0.5. The overall partial sum is 11 + 0.5(12.6) = 17.3.
There are 9 third order dame with no special significance. There is 1 third order dame on the edge. There are 2 third order dame that are adjacent to a stone. The third order partial sum is thus 11, which has an overall weight of 0.35. The overall partial sum is 17.3 + 0.35(11) = 21.15.
There are 10 fourth order dame with no special significance. There is 1 fourth order dame on the edge and 1 which is weak because the path to it passes by a stone. The fourth order partial sum is thus 11.8, which has an overall weight of 0.25. The overall sum is 21.15 + 0.25(11.8) = 24.10.
The estimated PON is the integer of {0.33(24.10) - 1.96 = 5.993}, yielding a PON estimate of 5. I.e., White can tenuki 4 times to a Black attacking play and still live. Maybe even 5 times, as 5.993 is almost 6.
I'm not sure I believe that, but I am not currently concerned with the potential weakness of the group.
The possible omission number (PON) is related to the strength or weakness of a group. A PON of 0 means that the group is unsettled; the attacker to play can kill, the defender to play can live. A PON of 1 means that the attacker to play can move to a position with a PON of 0. I have observed that in the opening pros generally try to make groups with a PON of at least 2.
The PON seems relevant to John's assessment. He is not saying that the White group has a PON of 1, since a White tenuki to a Black move would not be fatal. But I suppose that a "truly weak group" would have a low PON.John Fairbairn wrote:I find this interesting because where you see thickness I see a potential weak or heavy group.Knotwilg wrote:Me too I have a hard time to decide how to develop the left but O4 is still too close to White's thickness I think
As objective reasons for calling it potentially weak, it does not have any guaranteed eyes at all yet and is bounded by strong Black groups on both sides. If Black plays a move against it, White probably has to defend (or else accept a truly weak group), but his defensive move would be purely that - there is no move to make territory while defending.
Tajima and Sanechika have an algorithm for estimating the PON. It has not been, in my view, scientifically verified, but I thought that it would be fun to try to apply it to the White group.
"a" - to "d" represent the first to fourth order dame of the group. Note that the dame that get too close to opposing stones are not counted. To estimate the PON we use them to derive a weighted sum and then take a function of that sum.
There are 11 first order dame with no special significance. They each have a weight of 1, yielding a partial sum of 11.
There are 9 second order dame with no special significance. They have an initial weight of 1. There are 2 second order dame on the edge, which get an initial weight of 1.6, because of eye potential. There are 2 second order dame which are adjacent to a
stone, which get a low initial weight of 0.2, because of that. The second order partial sum is thus 12.6, which has an overall weight of 0.5. The overall partial sum is 11 + 0.5(12.6) = 17.3.There are 9 third order dame with no special significance. There is 1 third order dame on the edge. There are 2 third order dame that are adjacent to a
stone. The third order partial sum is thus 11, which has an overall weight of 0.35. The overall partial sum is 17.3 + 0.35(11) = 21.15.There are 10 fourth order dame with no special significance. There is 1 fourth order dame on the edge and 1 which is weak because the path to it passes by a
stone. The fourth order partial sum is thus 11.8, which has an overall weight of 0.25. The overall sum is 21.15 + 0.25(11.8) = 24.10.The estimated PON is the integer of {0.33(24.10) - 1.96 = 5.993}, yielding a PON estimate of 5. I.e., White can tenuki 4 times to a Black attacking play and still live. Maybe even 5 times, as 5.993 is almost 6.
I'm not sure I believe that, but I am not currently concerned with the potential weakness of the group.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: Where to play at the end of the Fuseki (practical exampl
And he shall come to judge the thick and the dead.Uberdude wrote:Maybe I can make clear my (mis?)use of the word thick by saying in the below position white's group is both thick and dead. It's not strong. Before it was strong-enough-for-now.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: Where to play at the end of the Fuseki (practical exampl
More fun with PON
The Chernobyl group
PON = int(0.33(9 + 0.5(9) + 0.35(9) + 0.25(9)) - 1.96) = int(4.277) = 4.
After
we have
PON = int(0.33(7.4 + 0.5(7) + 0.35(6) + 0.25(5.2)) - 1.96) = int(2.759) = 2.
Since Lee only tenukied once in this position, the PON estimate seems too high. (Not scientifically validated, as I said.) Note that Black's attack reduced the PON estimate by 2, not by 1, as we would expect from the algorithm.
would have preserved an actual PON of at least 2, which pros generally do in the opening. Lee later said that he should have played there, but he did not, so it is a close call.
The Chernobyl group
PON = int(0.33(9 + 0.5(9) + 0.35(9) + 0.25(9)) - 1.96) = int(4.277) = 4.
What does the PON estimate say?Uberdude wrote:In Lee's game Gu later attacked at a, and Lee tenukid and Gu later attacked again at b and Lee ended up making a small life in sente. Despite getting 2 tenukis from it Lee later said he should not have ignored the initial attack but jumped to c to preserve the power of the thickness.
After
we havePON = int(0.33(7.4 + 0.5(7) + 0.35(6) + 0.25(5.2)) - 1.96) = int(2.759) = 2.
Since Lee only tenukied once in this position, the PON estimate seems too high. (Not scientifically validated, as I said.) Note that Black's attack reduced the PON estimate by 2, not by 1, as we would expect from the algorithm.
would have preserved an actual PON of at least 2, which pros generally do in the opening. Lee later said that he should have played there, but he did not, so it is a close call.The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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DrStraw
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Re: Where to play at the end of the Fuseki (practical exampl
PON?
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).
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Bill Spight
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Re: Where to play at the end of the Fuseki (practical exampl
Possible Omission Number. I. e., how many times you can tenuki and still live.DrStraw wrote:PON?
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.