Life In 19x19

Something else to think about. When White approaches at below if you immediately switch to the lower left with , LZ 222 sees only about a 0.2% difference between that move and 'a' or 'b'.

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[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . a . 1 . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . b . . |
$$ | . . . . . . . . . . . . . . . . . . . |
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$$ | . . . O . . . . . . . . . . . O . . . |
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$$ +---------------------------------------+[/go]

Once you respond with below as in the game, now playing in response to is a -10% to 11% play in LZ's calculation.

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[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . 1 . 3 . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
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$$ | . . . . . . . . . . . . . . . . 4 . . |
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$$ | . . . O . . . . . . . . . . . O . . . |
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$$ +---------------------------------------+[/go]

By the time you exchange for (the game sequence), changing your mind now and playing is around -15%. Choices have consequences. Changing our minds halfway through a sequence where we have committed more resources allows the opponent to damage us more than if we had never gotten involved.

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[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . X . . . . . . . . . 1 . 3 4 . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
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$$ | . . . . . . . . . . . . . . . . 6 . . |
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$$ | . . . O . . . . . . . . . . . O . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

ez4u wrote:Changing our minds halfway through a sequence where we have committed more resources allows the opponent to damage us more than if we had never gotten involved.

Judgement is required, however, is it not?

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[go]$$Wc 10-11% loss
$$ +---------------------------------------+
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$$ | . . . X . . . . . . . . . 1 . 3 . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
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$$ | . . . . . . . . . . . . . . . . 4 . . |
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$$ | . . . O . . . . . . . . . . . O . . . |
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$$ +---------------------------------------+[/go]

After attaches LZ reckons as losing 10-11%.

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[go]$$Wc Loss or gain?
$$ +---------------------------------------+
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$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . X . . . . . . . . . 1 . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
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$$ | . . . . . . . . . . . . . . . . 4 . . |
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$$ | . . . O . . . . . . . . . . . O . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

But what about after the slide, ? My guess is that loses less according to LZ, or may even make a gain.

In your second diagram, LZ wants to tenuki and invade the 3-3 at R3. But the approach is fine, with -0.5%, and is slightly better than solidifying the corner with R17

So yes, the situation is very different, and you should not tenuki the attach in the first diagram.

@Bill, if your point is to illustrate why bots have such a low opinion of the slide, well done.

ez4u wrote:@Bill, if your point is to illustrate why bots have such a low opinion of the slide, well done.

No, my point is really what I said. Judgement is required. And it is not easy. Humans tenukied after the slide long before the bot era. And, as an SDK, I recall being extremely puzzled why pros stopped playing in certain areas of the board when they did. When are we halfway through a sequence, and when are we not?

Bill Spight wrote: Second, "similar positions" is a vague phrase. Look again at Uberdude's analysis. He started by identifying connected groups of stones. Then he counted their dame. Then he highlighted cutting points. You could have a "similar position" where Black had no cutting points, and then White might indeed be dead. Even if the White group captured the two Black stones in the middle, that might give him only one eye .

Yes, similar is hard to define.

If anyone else reading this has similar judgement issues: by accident I saw a recent lecture by Nick Sibicky (#340) where he discusses situations where one player has a group completely surrounded by opponent's stones. In his example white had six liberties left - not unlike what my opponent had in my game. He says something blatantly obvious, but insightful about it: the group is not dead as long as any attaching group has fewer liberties. Then he shows how he uses this in one of his games, cutting the opponent's surrounding stones and chasing the fragments - all the time keeping at least one of them short on libs - and eventually surviving this way.

Anyway, I am going back to my Wilcox, and taking his rules a little more literally than I have before. Catch of playing on Tygem to learn to fight, is that one picks up bad habits.



@ez4u:

Thank you for the computer evaluations. While they can give some help to the situations in my horrible game, it can still be hard to find out when a single stone is worth saving (and worth the moves to capture).

Like Bill in his SDK days, I also wonder about pros tenuki-ing in the middle of sequences - and why not at some other times. While I can learn when it can be done, it is different fom understanding why and how to handle opponents trying to pounce on that.

As a general point, contact moves tend to make urgent local situations, so if you tenuki from contact moves (attachment and hane in game) you will suffer more than if you tenuki from non-contact moves (the slide).

This is better for white:

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[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . 1 . 3 . . . |
$$ | . . . . . . . . . . . . . . . X 5 . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

than this one:

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[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . X . . . . . . . . . 1 . . 5 . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

White has a bigger and stronger territory/eyespace and the black 4-4 stone is in more danger.