SoDesuNe paves his road to Shodan

SoDesuNe · **#261**

Yeah, problem 98, I got wrong ^^ Problem 94 is one of those with an "invisble move". I often have a fairly good instinct for starting points but some of the quiet, patient moves elude me frequently. Problem 108 was no problem for instance, it just needed time to sort the variations.

Do you mind telling me which solution diagrammes are wrong? :o

logan · **#262**

SoDesuNe wrote:

[...] Problem 94 is one of those with an "invisble move". I often have a fairly good instinct for starting points but some of the quiet, patient moves elude me frequently.

Then 154-62 are right up your alley

SoDesuNe wrote:

Do you mind telling me which solution diagrammes are wrong?

SoDesuNe · **#263**

154-162 weren't that difficult surprisingly because after the first two, ones gets to guess the right first move quite fast =D Nevertheless I still failed two problems.

Problem 185:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . . . X O . | $$ ------------------+[/go]

Regarding problem 223, I have to admit I don't see the error ^^ But as long as the solution is correct, I guess this is a minor flaw.

I'm now at the 253rd problem... and I'm really bad at liberty races : /

RBerenguel · **#264**

SoDesuNe wrote:

154-162 weren't that difficult surprisingly because after the first two, ones gets to guess the right first move quite fast =D Nevertheless I still failed two problems.

Problem 185:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . . . X O . | $$ ------------------+[/go]

Regarding problem 223, I have to admit I don't see the error ^^ But as long as the solution is correct, I guess this is a minor flaw.

I'm now at the 253rd problem... and I'm really bad at liberty races : /

Solution for 185?

SoDesuNe · **#265**

Well, you have to at least try first =D

RBerenguel · **#266**

Editing diagrams on iPad is tricky. Have an idea, but I hate semeais...

SoDesuNe · **#267**

Then go with coordinates : )

RBerenguel · **#268**

SoDesuNe · **#269**

RBerenguel wrote:

Hint:

Kirby · **#270**

Re: 185

SoDesuNe · **#271**

Kirby wrote:

Re: 185

Kirby · **#272**

I thought about this a little more, and it's interesting to consider which of the two moves are more "optimal".

My initial thoughts were based on points - namely, with the book answer, you can avoid seki without having to fill in your own points to capture, as described here:

Suppose we go with the suggested book alternative. White has the option of threatening seki, forcing black to capture. Black fills in two of his liberties in doing so.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O 4 | $$ . . . . O X X X 6 | $$ . . . X O O X . X | $$ . . . X X X O X 3 | $$ . . . . X O O O X | $$ . . . . 1 2 7 O 5 | $$ ------------------+[/go]

6 captures + 1 point - 1 capture by white = 12 points

Alternatively, with the book solution, we don't have to fill in the marked intersections, and can avoid seki completely.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O 2 | $$ . . . . O X X X 3 | $$ . . . X O O X . X | $$ . . . X X X O X C | $$ . . . . X O O O X | $$ . . . . . 1 X O C | $$ ------------------+[/go]

5 captures + 4 points = 14 points

Even if white captures the two stones and black throws in, it's still more than the 12 points achieved by the alternative move.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O 2 | $$ . . . . O X X X 3 | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . 4 5 . O . | $$ ------------------+[/go]

6 captures + 4 points - 2 captures by white = 14 points

Ko Threats
But then we can consider the idea of ko threats. Even if we can avoid seki with more points using the book's solution, do ko threats change between the variations?

With the book alternative move...

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . 1 . X O . | $$ ------------------+[/go]

White can use the seki-threatening move as ko threat #1, inducing black to play at the marked spot:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X C | $$ . . . . X O O O X | $$ . . . . X W . O . | $$ ------------------+[/go]

White can play his sente here for ko threat #2...

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O W | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X X | $$ . . . . X O O O X | $$ . . . . X O . O C | $$ ------------------+[/go]

And here for ko threat #3. If black responds to all, white is now captured without ko threats in the area.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X W | $$ . . . X O O X . X | $$ . . . X X X O X X | $$ . . . . X O O O X | $$ . . . . X O C O X | $$ ------------------+[/go]

So maybe 3 ko threats or so...

Now what about the book move?

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . . 1 X O . | $$ ------------------+[/go]

Supposing white follows the order given above to illustrate point difference, white can make a ko threat similarly to the alternative book move threat:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O W | $$ . . . . O X X X C | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . . X X O . | $$ ------------------+[/go]

Later, white can capture as another ko threat (#2). To avoid seki, black throws in:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . W C . O . | $$ ------------------+[/go]

White can threaten to move out with ko threat #3, but does black even need to answer?

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . W O X . O . | $$ ------------------+[/go]

It's hard to say. Maybe if there are white stones nearby to the left, white could play like this to link up to the left of the diagram:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . W . O O X . O . | $$ ------------------+[/go]

So maybe to prevent this, black responds to the ko threat:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . B O O X . O . | $$ ------------------+[/go]

If there are nearby stones, then, maybe white has another ko threat here, for a 4th ko threat:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . W . X O O O X | $$ . . B O O X . O . | $$ ------------------+[/go]

I can't see the "3rd ko threat" in this situation as being a threat unless we know that white can get enough liberties by escaping to the left. So perhaps depending on this, white might possibly have an extra ko threat using the alternative to the book move.

In that sense, perhaps playing solidly eliminates this possible ko threat (if it exists), at the expense of the two points required to fill in order to capture and avoid seki.

In general, I like being able to keep the two points by using the book solution. However, it's true that this leaves aji and an extra possible ko threat if there are nearby friendly white stones...

Interesting problem!

logan · **#273**

Kirby wrote:

I thought about this a little more, and it's interesting to consider which of the two moves are more "optimal".

My initial thoughts were based on points - namely, with the book answer, you can avoid seki without having to fill in your own points to capture, as described here:

Suppose we go with the suggested book alternative. White has the option of threatening seki, forcing black to capture. Black fills in two of his liberties in doing so.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O 4 | $$ . . . . O X X X 6 | $$ . . . X O O X . X | $$ . . . X X X O X 3 | $$ . . . . X O O O X | $$ . . . . 1 2 7 O 5 | $$ ------------------+[/go]

6 captures + 1 point - 1 capture by white = 12 points

Alternatively, with the book solution, we don't have to fill in the marked intersections, and can avoid seki completely.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O 2 | $$ . . . . O X X X 3 | $$ . . . X O O X . X | $$ . . . X X X O X C | $$ . . . . X O O O X | $$ . . . . . 1 X O C | $$ ------------------+[/go]

5 captures + 4 points = 14 points

Even if white captures the two stones and black throws in, it's still more than the 12 points achieved by the alternative move.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O 2 | $$ . . . . O X X X 3 | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . 4 5 . O . | $$ ------------------+[/go]

6 captures + 4 points - 2 captures by white = 14 points

Ko Threats
But then we can consider the idea of ko threats. Even if we can avoid seki with more points using the book's solution, do ko threats change between the variations?

With the book alternative move...

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . 1 . X O . | $$ ------------------+[/go]

White can use the seki-threatening move as ko threat #1, inducing black to play at the marked spot:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X C | $$ . . . . X O O O X | $$ . . . . X W . O . | $$ ------------------+[/go]

White can play his sente here for ko threat #2...

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O W | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X X | $$ . . . . X O O O X | $$ . . . . X O . O C | $$ ------------------+[/go]

And here for ko threat #3. If black responds to all, white is now captured without ko threats in the area.

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X W | $$ . . . X O O X . X | $$ . . . X X X O X X | $$ . . . . X O O O X | $$ . . . . X O C O X | $$ ------------------+[/go]

So maybe 3 ko threats or so...

Now what about the book move?

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O . | $$ . . . . O X X X . | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . . 1 X O . | $$ ------------------+[/go]

Supposing white follows the order given above to illustrate point difference, white can make a ko threat similarly to the alternative book move threat:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O W | $$ . . . . O X X X C | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . . X X O . | $$ ------------------+[/go]

Later, white can capture as another ko threat (#2). To avoid seki, black throws in:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . . W C . O . | $$ ------------------+[/go]

White can threaten to move out with ko threat #3, but does black even need to answer?

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . . W O X . O . | $$ ------------------+[/go]

It's hard to say. Maybe if there are white stones nearby to the left, white could play like this to link up to the left of the diagram:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . W . O O X . O . | $$ ------------------+[/go]

So maybe to prevent this, black responds to the ko threat:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . . . X O O O X | $$ . . B O O X . O . | $$ ------------------+[/go]

If there are nearby stones, then, maybe white has another ko threat here, for a 4th ko threat:

Click Here To Show Diagram Code: [go]$$Bc $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . O O O O O | $$ . . . . O X X X X | $$ . . . X O O X . X | $$ . . . X X X O X . | $$ . . W . X O O O X | $$ . . B O O X . O . | $$ ------------------+[/go]

I can't see the "3rd ko threat" in this situation as being a threat unless we know that white can get enough liberties by escaping to the left. So perhaps depending on this, white might possibly have an extra ko threat using the alternative to the book move.

In that sense, perhaps playing solidly eliminates this possible ko threat (if it exists), at the expense of the two points required to fill in order to capture and avoid seki.

In general, I like being able to keep the two points by using the book solution. However, it's true that this leaves aji and an extra possible ko threat if there are nearby friendly white stones...

Interesting problem!

Kirby, I'm happy that you found so much interest in a single problem. As you may have suspected, the tension between ko threats and points (and often additional aspects) is nearly universal in L&D problem books. A sign of a good L&D book is how consistently the author chooses one of these to be the right solution across all multi-solution problems. If you're joining us in the book, then you may wish to tally the author's choices and see where he finishes (something I've occasionally done in my problem books).

Perhaps you can also imagine how much more difficult these tensions are in Endgame problem books. I think it's a serious issue that authors of these books have to have settled before they get started and if they wish to publish a great book.

Kirby · **#274**

Hi logan,
I agree with the points you make on the importance of consistency. Regarding tallying the author's choices, I don't have the book (Weiqi Life and Death 1000 Problems, right?), but perhaps I'll add it to my wishlist. Based on the senseis link you provided earlier, it looks to be a good book!

SoDesuNe · **#275**

So far I can really recommend Weiqi Life and Death 1000 Problems. It has a lot of neat problems (close to Go/Segeo Tesuji Problems but not as big in scale obviously and comparable to Maeda's Intermediate Level Problems) and also quite a few problems I did not see (or recognized, though I'm fairly good at that) before.
Especially Killing Eyes and Capturing Races are two sections (translations from Sensei's Library) which taught me new moves (Tesujis?) I had not seen before. It's really great because the latter is a big weakness of mine.
Looking forward to the following 20 sections : D

RBerenguel · **#276**

SoDesuNe wrote:

So far I can really recommend Weiqi Life and Death 1000 Problems. It has a lot of neat problems (close to Go/Segeo Tesuji Problems but not as big in scale obviously and comparable to Maeda's Intermediate Level Problems) and also quite a few problems I did not see (or recognized, though I'm fairly good at that) before.
Especially Killing Eyes and Capturing Races are two sections (translations from Sensei's Library) which taught me new moves (Tesujis?) I had not seen before. It's really great because the latter is a big weakness of mine.
Looking forward to the following 20 sections : D

Could I (~5k I guess) solve some of them? I love having new books

SoDesuNe · **#277**

Hmm, I've just solved the first three sections, so I can't say for sure but I think overall it's too hard for 5-kyu. On Sensei's Library logan estimated the book around 1-kyu to 3-dan, I think that fits quite well.

RBerenguel · **#278**

4 stones to go then!

SoDesuNe · **#279**

I just replayed the first game of Chen Yaoye's fourth Tianyuan defence and I couldn't help myself, I needed to put down my awe in some comments : D

Record form http://igokisen.web.fc2.com/cn/tn.html

SoDesuNe · **#280**

I completed section five (Seki) from Weiqi Life and Death 1000 Problems a while ago and as christmas holidays draw nearer my anual Go hiatus arrived ^^ So, I didn't start section six, yet. I guess this won't change until January.

The dark times are reserved for (fictional) books and videogames =D

I also thought about starting a new study journal since I am now Shodan on two accounts (you can even see the rank in graph in the first post ^^) but I guess, I try to make Nidan first. That way I'm completely sure I'm at least Shodan : D

SoDesuNe paves his road to Shodan

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