well, in chinese version, that's 'Connect.Cut' so the problem is about either connecting or cutting. I think it does make confusion with 'connect-and cut'

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solutions(?)

My statement was in reference to GoChild's Entrance->Basic->Jie problem pack, not to Gokyo Shumyo which I've read is more appropriate for low to mid-dan ranked players.


I don't want to get in the habit of automatically starting kos. In an actual game starting an un-winnable ko without having useful ko threats elsewhere probably would be "an even greater failure".

Its not about automatically starting kos -- its about learning to recognize how to start them when you need to. Since this is the ko/jie problem set, these are examples/sets of problems where we're being told we need to.

Maybe I'll go back to that set in the future if I find myself not being able to start a ko when I need to. Given the huge number of other problem sets on GoChild I don't think it will be anytime soon.

When you do the problems on GoChild, you do realize of course that GoChild is most likely pirating from many Asian go problem books for which it probably has not obtained the permission of the author or the publisher.

Of course if you as a user own physical copies of most every Asian go problem books (in print or out of print), then it wouldn't really be a concern.

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Go is such a beautiful game.

No, actually I don't realize that. Do you have evidence that they are doing so?

The content is mainly listed by the translated book names. If you have some Asian go books, look at your book and compare with the content on the site.

Does Gochild say "posted with the permission of the publisher"?

Does Gochild offer a selection of the content or the whole of the content of the book?

If you look at the advanced section, check out "Sky Dragon 1000"
It's in two parts with 500 problems each. Now compare with the books "Heavenly Dragon Diagrams 1 & 2" in my blog for the entry "Kweon Kap-yong Problem Books". 500 problems in each of these books.

Now look at the Go Seigen selections in advanced, check out "Long lived stones". There are 200 problems. Now compare with the book "The Long-Lived Stone Is Not Old" in my blog. 200 problems in the book.

I'm sure the copyright for those books are still in effect. They are not exactly ancient go manuals.

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http://tchan001.wordpress.com
A blog on Asian go books, go sightings, and interesting tidbits
Go is such a beautiful game.

Hmm, that is suspicious, but who knows, maybe they have permission? Perhaps you should contact the site & voice your concern. If they don't respond appropriately I'm sure Google will since they host it & have terms which forbid illegal activities.

As I'm still in the Entrance section I haven't really looked at what's in the Advanced. Many of the problems in Entrance were uploaded by a go school in China, and one set was apparently created by one of the site's owners. Perhaps schools in China are allowed to use copyrighted material without permission? I haven't a clue.

Interesting that you say that. For me it's often not at all obvious, and there are indeed quite a few problems in the Jie section that I got wrong. There are of course easy kos to start, but it gets a bit trickier when you have to judge whether a group can only be saved by a ko, and there's also the matter of starting the ko in the most advantageous way. In any case, starting a ko is often not on my radar, and I particularly like this set of problems because it's one of the few I've found that specifically deal with ko. Most problem sets deal with ko as an afterthought, one possible route to failure, when it can also be the only possible route to success.

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Patience, grasshopper.

I'm a bit confused - how can you know that you're not able to start a ko when you need to without doing tsumego? Without doing tsumego, you may look at your shape and say "Dead" or your opponent's shape and say "Alive" and not see that there is a ko you can start to change that. On the same note, you might overlook that one of your shapes which appears to be alive is actually killable via ko or one of your opponent's dead groups can actually live via ko. This could easily take a smooth victory and turn it into a humiliating defeat.


How? Let's say that the value of a non-ko-threat move on the board is x. Let's also say that there is a position on this board where you can start a ko. Instead, you play the move of value x. Your opponent then removes the ko aji from the board, enabling you to play another move of approximately size x as well (it could be bigger or smaller depending on whether you were threatening a group, but let's assume that, since your opponent tenukied, your move did not threaten too much). You have now made a profit of approx. 2x not including the ko position.

Now let's say that instead, you start the ko fight. Let's say that if you lose that ko fight, you locally lose y points (if it is a flower-viewing ko for you, as most of the problems posted so far have been, than y is relatively small compared to most other moves on the board). Now, it seems the worst case scenario is that you make 2x profit elsewhere - that is, you are not able to find a single ko threat and so you just get two big moves in a row. However, more likely, you will be able to find a ko threat worth > 2x (even if not drastically so) which your opponent will not respond to. So as long as 2x + y < your ko threat, it was a profitable ko to start.

That being said, it may have been more profitable to wait until the value of your unanswerable ko threat was larger, but I must disagree when you say that starting a ko too early is "an even greater failure" than not starting the ko at all.


To me, this seems tantamount to a 9k saying "Oh, I'll learn about the L-group and the J-group later when I see it occur in actual play." A couple of problems with this:

1) When you do see it in actual play you are more likely to not know what to do or to screw up because you have not studied it.

2) You are not going to see such a shape in actual play because the shape is not natural to you. I rarely ever noticed the L-group or any other such group before I learned their statuses and how to kill them. It was only after I studied them that I realized "Hey, if I do this and this and this, his shape becomes an L+1 group, which I can then kill!" If I hadn't studied these things until I could see them in my actual play, I would've spent a lot longer struggling to improve to my current level than I did.

Even now, if I've done enough tsumego of a particular pattern, I can drive my opponent to shapes I know I can punish which, had I not done tsumego, I would never have even seen. You may say "Well, that's life and death, and I'm only talking about kos." But they are not separable. For instance, although many people say the J-group is dead, did you know that the person forming the J-group can quite often alter one move in the sequence to make a ko?

Click Here To Show Diagram Code

[go]$$Bcm1 Black to make a ko. Any other move dies miserably.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X O O . . . . . . . . . . . . |
$$ | . X X X O . . . . . . . . . . . . . . |
$$ | . O O O O . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Anyway, my overarching point is, you will very rarely see shapes and think "There's a deficiency there," or "There's an unintuitive way to live there" until you've already done problems/studying of similar shapes.

Of course, don't think I'm yelling at you. You can feel free to do tsumego however you want. But if you're doing tsumego to improve, I don't think putting off a particular branch of it for whatever reason is a very good idea.

P.S. Shaddy, I didn't look at your second solution, but the first one is right.

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I think it's pretty cool that there is a section that is specialized on ko. Since I have missed easy ko problems in books, I will start these problems right this evening. There is only one minor issue: If I know that I should start a ko, then it is much easier - maybe it would be more helpful to mix ko problems with conventional L&D problems, so that you have to find out yourself whether you have to start a ko or not.

IIRC, they mix them all up in the kyu level testing section at the end..

You do recall correctly, I'm doing those problems now and seeing ko problems occasionally.

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Yep. It is really good practice, since I have the bad habit of glancing at groups like that and declaring them dead. I keep saying "Wait, there's no solution... oh, duh, ko."

Thanks for the example. Here is the SGF file, with a couple of comments.



I am quoting the following exchange as representative.




It is unfortunate, in a way, that this is presented as a whole board problem. Given the whole 7x7 board, Black can resign. But I suppose that the interactive software requires a full board. Traditionally, problem books often showed a number of problems on different parts of the same board. You were supposed to regard them as independent. Surely for these problems you are supposed to regard them as local, not whole board problems.

Now, as you point out, in a real game kos are not independent of the rest of the board. And there are many ko problems that are full board problems. However, there are many tsumego problems, such as this one, where ko is the answer. Black to play cannot live outright, but can make a ko. That is the point of the problem.



That may be your experience, but the vast majority of problems involving ko have to do with making a ko or with preventing one, not with winning it.



One reason for your belief is that you are viewing these as whole board problems. That appears to be an accident of the software. Some GoChild problems may be whole board problems, but this one, and ones like it, are not.

Another reason appears to be that you think that you should not start a ko unless you can win it. In truth, however, often the opposite is the case. You should start a ko because you cannot win it. Yes, that seems paradoxical. But read on.

One of the first go books I bought discussed a standard situation where Black, say, could invade a White corner and make a ko. However, White took the ko first. To my surprise, the book argued that Black might invade and start the ko, even if she could not win it. It showed a full board situation where Black could do just that. I puzzled over that, and it took me a long time before I fully understood the point. At first, I thought that invading and making the ko induced White to make a smaller play (winning the ko) than he would otherwise make. But that's silly. Let me illustrate the real points with the example problem.

To make things clear, let us assume that the corner position is part of a whole board, and that neither player has a ko threat, nor will either player create a ko threat large enough to win the ko during play. How much each ko move gains depends on the surroundings, because they affect the size of plays if Black wins the ko. Let's assume that each ko move gains 11 points. For the sake of illustration, let's assume that the largest play elsewhere on the board gains 10 points, and that otherwise things are normal, with the size of plays gradually reducing as the game goes on. Let us also assume that it is White's turn to play.

White could kill the corner, preventing the ko. That is, in fact, the largest move on the board. But that would be wrong, because White can win the ko without ignoring a Black threat. (White is komaster.) White takes a 10 point move. (Let's assume that there are a few 10 point moves on the board.)

Now suppose that Black believes that, even though playing the ko would gain more than 10 points, she should not do so because she cannot win the ko. So she leaves the ko alone and takes a 10 point move. We can see where this is heading. Neither player will play in the corner, and we will finally reach a position where the rest of the board has been played out and the Black group in the corner is dead. Since the top play gains 10 points, we can estimate the gain for White as half of that, or 5 points.

Now suppose that Black starts the ko, even though she will lose it. Then White must take the ko, Black takes a 10 point move, White wins the ko, and then play continues with Black taking a 10 point move. Let us compare this with the other scenario.

White has gained 11 points by killing the corner. However, in both scenarios the corner is dead, so that is the same. On the rest of the board, in the first scenario, where Black did not make the ko, White gained approximately 5 points. In the second scenario, where Black made the ko immediately, White gained 10 points, and then Black gained 10 points, and then Black gained approximately 5 points, for a net of approximately 5 points for Black. The difference between the two is approximately 10 points, which is how much the largest play outside of the ko gained.

In go we talk about the ko exchange, which is how much the loser of the ko gains in exchange for losing the ko. In general, the sooner the ko is played, the larger the ko exchange, and therefore the loser of the ko should normally start the ko as soon as possible. As paradoxical as that may sound.

So you see, these problems are not teaching bad habits by suggesting that a player should make a ko, even though he cannot win it. That's a good habit.

N. B.: There are cases where a player has a choice of local plays, one of which leads to a ko he cannot win, and another that does not. Often the player should choose the latter, of course.

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This space intentionally left blank.

(Accidental duplicate post. )

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Thanks for your comments everyone, especially Bill's lengthy explanation.

I bow to your wisdom, and will do the Jie section next.

What? You wrote all that twice, by accident?

I liked your post too, but I must admit, I am far from understanding it - though not for lack of trying. My confusion stems at least partly from not knowing which moves you are talking about. In the SGF your last comment is:



Which is "that move?" Who is gaining 10 pts per move?

In your explanation, you say these (among other) things that I don't follow:



First of all, what exactly is a "ko move?" Is it in the illustrated case any move by either white or black that affects blacks struggle for life, such as a2, a1, b1 or c1?

When you say that the gain is dependent on the surroundings...um...uh... what? Does that mean that if black wins the ko, in addition to the 4 points he wins + the 20 something points white doesn't get, he gains some intangible benefit from white no longer being necessarily alive. Is this intangible gain the gain that you have tacked the price tag of 11 pts per move onto?

A bit later, in your description of black's erroneous ways, you write:



What is the "top play?" When I know what that is, will it make sense to me that white's gain is half of that? (I doubt it)


If you or anyone else would care to clarify these concepts, I'd be ...still in a fog, but with my headlights on.

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When I made an edit, I found that apparently I had edited the second post. How it got there, I do not know.



Sorry for not being clearer.



The move to capture four stones.



Each player. Every move in the SGF file gains exactly the same number of points, on average (10+ points). Edit: I am counting the first three moves as a unit.



A move that takes or wins a ko.



If Black wins the ko, he threatens to extend beyond the confines of the corner. Those possibilities affect the size of a ko move, and the surroundings affect the size of those possibilities. (If this were an endgame problem, the surroundings should be clearly defined, but it is not, it is a life and death problem.)



The largest play.



Suppose that the top play gains 10 points. With no kos, the maximum that the player to move can gain is 10 points, and the minimum is 0. We can take the average, 5 points, as an estimate. It turns out that this is a pretty good estimate, even when there are potential kos. For instance, suppose that there are plays that gain 10 pts., 6 pts., 4 pts., 2 pts., 1 pt., and 0.5 pt. (This is actually pretty unrepresentative of go, which typically has many more plays that are much closer together in size.) The player with the move gains 10 - 6 + 4 - 2 + 1 - 0.5 = 6.5 points. That is only 1.5 points more than the estimate. For a real go position the error will typically be less than 1 point.

N. B. The popular way of evaluating plays does not tell you how much the play gains, but twice that. If you use that method, you have to divide by 4 to estimate the gain.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.