Loons wrote:Quick question for Joaz:
Just in passing, what exactly is your arcane knowledge of the 5-4 ? You're up with the modern variations so your local choice will be better? In my experience 5-4s don't normally go that complexly.
...
'Exactly' is not possible to answer without pages of diagrams and a more organized cranium. Suffice to say that the 5-4 with the subsequent 3-4 response is full of traps, primarily because the invader can be locked in, but still there is enough room for the invader himself to be undercut.
The average beginner learns the 4-4 early, because he is given it as a handicap. He learns that the 3-3 is safe as long as he gets enough eye space. When he plays even games, and invades a 4-4 with a 3-3, he never worries about his low stone being undercut, because it is almost impossible to do so.
Then, these unstated beliefs can easily be transferred to the 5-4, where they turn out not to be quite true. It looks superficially the same: a low stone living under a high stone. He may even know some 3-4 joseki, so he feels comfortable. But with the 5-4 he is a stone behind, and the 3-4 is not as safe as the 3-3.
As an example:
$$Wc Seems normal enough
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . 1 , 2 . . |
$$ | . . . . . . . . . . . . . . 4 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Wc Seems normal enough
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . 1 , 2 . . |
$$ | . . . . . . . . . . . . . . 4 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
$$Wc Two extensions off of a crosscut \n can't be bad for black...right?
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . 1 6 2 . . |
$$ | . . . . . . . . . . . . . 7 4 5 . . . |
$$ | . . . . . . . . . . . . . . 8 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Wc Two extensions off of a crosscut \n can't be bad for black...right?
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . 1 6 2 . . |
$$ | . . . . . . . . . . . . . 7 4 5 . . . |
$$ | . . . . . . . . . . . . . . 8 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Now it is so tempting to play separating plays like 'a' or 'b'. Both are atari, so they are clearly sente.
$$Wc
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . X . . . . . , . . . b O X X . . |
$$ | . . . . . . . . . . . . . O X O . . . |
$$ | . . . . . . . . . . . . . c X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Wc
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . X . . . . . , . . . b O X X . . |
$$ | . . . . . . . . . . . . . O X O . . . |
$$ | . . . . . . . . . . . . . c X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
But, 'a' turns out like this:
$$Wc Something will die
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . X . . . . . , . . . 3 O X X . . |
$$ | . . . . . . . . . . . . . O X O . 5 . |
$$ | . . . . . . . . . . . . . 4 X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Wc Something will die
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . X . . . . . , . . . 3 O X X . . |
$$ | . . . . . . . . . . . . . O X O . 5 . |
$$ | . . . . . . . . . . . . . 4 X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
...and 'b' like this:
$$Wc White steals a big corner.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . 3 . . . . |
$$ | . . . X . . . . . , . . . 2 O X X . . |
$$ | . . . . . . . . . . . . . O X O . 5 . |
$$ | . . . . . . . . . . . . . 4 X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Wc White steals a big corner.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . 3 . . . . |
$$ | . . . X . . . . . , . . . 2 O X X . . |
$$ | . . . . . . . . . . . . . O X O . 5 . |
$$ | . . . . . . . . . . . . . 4 X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
So contrary to most player's intuitions, the seemingly submissive 'c' is best. It continues like this:
$$Wc Black has to look after two eyeless groups.\n Both tempting ataris still fail.
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . 6 . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . X . . . . . , . . . b O X X 4 . |
$$ | . . . . . . . . . . . . . O X O 5 3 . |
$$ | . . . . . . . . . . . . . 2 X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Wc Black has to look after two eyeless groups.\n Both tempting ataris still fail.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . 6 . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . X . . . . . , . . . b O X X 4 . |
$$ | . . . . . . . . . . . . . O X O 5 3 . |
$$ | . . . . . . . . . . . . . 2 X 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Now the hane seems natural:
$$Bc Alas, black is tricked again
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . 3 . |
$$ | . . . . . . . . . . . . . . . . 1 O 5 |
$$ | . . . . . . . . . . . . . . . O 2 X . |
$$ | . . . . . . . . . . . . . . . . . 4 . |
$$ | . . . X . . . . . , . . . . O X X X 6 |
$$ | . . . . . . . . . . . . . O X O O O . |
$$ | . . . . . . . . . . . . . X X O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
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[go]$$Bc Alas, black is tricked again
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . 3 . |
$$ | . . . . . . . . . . . . . . . . 1 O 5 |
$$ | . . . . . . . . . . . . . . . O 2 X . |
$$ | . . . . . . . . . . . . . . . . . 4 . |
$$ | . . . X . . . . . , . . . . O X X X 6 |
$$ | . . . . . . . . . . . . . O X O O O . |
$$ | . . . . . . . . . . . . . X X O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Anyway, that is just a sample of some of the non-intuitive problems that can arise. FWIW, I won't try this, primarily because it is the best know trap, and he has probably seen it. Also, there are variations that require the ladder heading northwest to be favorable for white, and black just played there.