I'm re-reading 200 Endgame Problems. The first time round, many years ago, I went through it with a "spot the key move" attitude, and thought it was pretty easy. This time round, I'm setting the bar higher in terms of understanding why the key move is good, and seeing more of the variations, and I'm finding it much more challenging. Great to have a book that works on more than one level! I wonder if Shirae is trying to nudge us in the direction of effortful practice, in the same way that JF makes explicit in his variation-free Genjo-Chitoku?

Anyway, enough waffling. I'd like to take a dozen or so problems from the book and dig deeper, find the insights that aren't in the two solution diagrams per problem that you get. First up is part 1 problem 13.

Click Here To Show Diagram Code

[go]$$B Black to play
$$-----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . O . . X X . |
$$ . O . . . O X X O O . |
$$ . . . . . O O O X . . |
$$ . . . . . . . . X . . |
$$ . . . . . . . O X . . |
$$ . . . . . . . . X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |[/go]

Summary of book solution

What's not discussed is this alternative move, a shape which appears as the solution to some later problems. What is white's reply to in the next diagram?

White's reply:

Yes, that's it. Took me some effort to understand why it's actually a good result for white.

Next up, part 1 problem 30.

Click Here To Show Diagram Code

[go]$$B Black to play
$$-----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . . O X . . |
$$ . . O . . O . O X . . |
$$ . . . O O X O O X . . |
$$ . . . . . X X X . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |[/go]

This is what not to do:

Click Here To Show Diagram Code

[go]$$B The ordinary moves
$$-----------------------+
$$ . . . . . . 2 1 3 . . |
$$ . . . . . . 4 O X . . |
$$ . . O . . O . O X . . |
$$ . . . O O X O O X . . |
$$ . . . . . X X X . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |[/go]

Here's the book solution:

Now it might not be obvious at a glance that the solution is actually better than the ordinary moves. (At least, it wasn't obvious to me.) So this is a good counting exercise: how many points has black gained in the book solution compared with the ordinary moves?

Black gains ...

@Gomoto: I think that Black gains more than that, because to capture the three stones, White has to take gote, but on the other hand Black can also take gote to save his three stones?

My understanding in this situation is that...



I'm bad at endgame calculations, so I'd be interested in having my analysis corrected, if there are errors.

_________________
be immersed

Since I didn't study endgame theory seriously, it would be a miracle if my answer was correct, but here it is anyway. At least one of us is wrong.

I am a simple man. With the optimal answer black gains at least 1 point. And there is the additional potential for even more gains (Related to the rest of the board position.)

That is enough endgame theory for my needs

In pure area scoring, Black only gain sente

Well, I'm posting these because I'm interested in endgame theory and want to learn more :-) It's not that I need more endgame theory though, what I really need is to not lose all those middlegame fights, but that's a different conversation...

So for this one I get the same as Kirby. Of course that doesn't mean I'm correct, I'm still learning this stuff too. My first impression of jlt's analysis was that in the 1-2-3 sequences, move 1 reverses. So the WWW and BB diagrams should never happen with correct play.

It's the same as the basic hane-connect:

Click Here To Show Diagram Code

[go]$$B Three-move sequence
$$ X X X O O O
$$ . . 3 1 2 .
$$ -------------[/go]

You'd never analyse the following position:

Click Here To Show Diagram Code

[go]$$B White to play
$$ X X X O O O
$$ . . . 1 2 .
$$ -------------[/go]

because for black to play 1 and then abandon the position is a loss for black. If black 1 goes on the board and both players are making the best moves, then you'll always see 1-2-3 as a unit.

But actually, jlt's diagrams are not quite the same thing, because the 1-2 exchanges there don't actually make the position worse for the first player, they just make the position no better. I think that in a whole-board position where the other moves are small enough that 1 is the best local move, then 2 would be sente, which is why you'd still treat 1-2-3 as a unit for counting purposes (although in practice you could play 1, leave it alone for a while, then do 2-3 later). So not technically a "reverse", but same effect.

I haven't read it yet, but I believe Robert Jasiek's Endgame 3 has some theory on "long sequences" which goes into this in more depth. And someone please tell me if I'm overthinking this.

You could actually analyze that position, xela; it is useful to know sometimes how much a lossy ko threat loses.

See https://lifein19x19.com/viewtopic.php?p=252422#p252422

Still confused.



Well, I should really read some endgame books. I am currently working on tesuji but after that I should learn to count.

Simple mistake way White has 6 points to baseline.
Tesuji variation White has 0 or 6 points depending who gets the gote. So currently worth 3. Black has 1 extra from throw in. So white net 3-1=2.
6-2=4. Black gained 4 points from the tesuji endgame.

I have a little more confidence now that some other folks also got the same answer, so I'll give my interpretation as to why I have a different answer than this one:



As usual, I'm open to critique in this analysis.

_________________
be immersed

After watching the London New Year Tournament board 1 broadcasts in YouTube, I still wonder how these endgame discussions and the real games are so far apart.

Cheers,
Vesa

Wow, that got more interesting than I expected!

Next up, part 1 problem 53. I think this is easier, but I'm posting it because of a cute variation. And of course I could be wrong, there might be hidden depth here too.

Click Here To Show Diagram Code

[go]$$B Black to play
$$-------------------------+
$$ . . . . . . O . . . . . |
$$ . . . . . O X O O O . . |
$$ . . O O . . X X X X O O |
$$ . . . X O O X . . . X . |
$$ . . . X X X . . . X . . |
$$ . . . . . . . . . . . . |[/go]

Book solution:

Question 1: how can white make ko?
Question 2: instead of in the solution diagram, what move might black try to avoid ko, and how does it fail?

Ko:



Obviously many moves other than fail, but here is an unsuccessful attempt:

Yes, that's the I was thinking of. For a moment I thought I'd improved on the book solution, but alas, no.

White can also resist this way, perhaps not the best reply but it amuses me that the throw-in no longer works:

Next, problems 49 and 50 of part 1 are a nice pair for practising your counting.

Click Here To Show Diagram Code

[go]$$Bc Black to play: 'a' or 'b'?
$$---------------------+
$$ . . . . . a b . . . |
$$ . . . . . . . . X . |
$$ . . O . O . O O X . |
$$ . . . . . O . X . . |
$$ . . . . . . . . X . |
$$ . . . . . . X . . . |
$$ . . . . . . . . . . |[/go]

Click Here To Show Diagram Code

[go]$$Bc Black to play: 'a' or 'b'?
$$---------------------+
$$ . . . . . a b . . . |
$$ . . . . . . . . X . |
$$ . O . O O O O O X . |
$$ . . . . X X . X . . |
$$ . . . . . . . . X . |
$$ . . . . . . . X . . |
$$ . . . . . . . . . . |[/go]

In both cases:

• What's the best play for both sides after black a?
• What's the best play for both sides after black b?
• Which of a and b is best and by how many points?

Remember that the monkey jump is supposed to be sente. If you're looking at a gote sequence, think again about the choices for .
The book tells us which is best but doesn't do the counting. And the book also has this cute story about the name "monkey jump".