Anyone who’s ever done nonfiction writing or scientific/mathematics research will likely have experienced what writers call the “O, sh*t!” moment. Out of respect for the English language and in the interest of protecting the innocence of lifein19x19.com forum goers, I will instead refer to this as the “Holy Excrement!” event. Such an event occurs whenever people find out their argument or research was completely wrong or when the writing or research was already completed by someone else. In writing, that’s not the end of the world. The writer just goes on to add a sentence like “even though so-and-so already argued this exact point, it was important to reiterate this because …” and everything is fine. In scientific or mathematics research, this means the person just lost a few years of his or her life.
Anyway, after making

, I experienced just this kind of a “Holy Excrement!” event. I came to realize that I had completely missed a strong possibility for Black. Specifically, while I saw that Black can play at

, I failed to realize that the simple connection of

is sente.
- Click Here To Show Diagram Code
[go]$$Bc Prisoners: 
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . 1 O O O . . |
$$ | . . . . . . . . . . a O O 2 X O . X . |
$$ | . . . X . . . O . O b X X X 3 X O . . |
$$ | . . . X . O . . . . . . . O . X O . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Next, Black threatens to play at “a,” which instantly puts White to the test. Should White play at "a" (strengthening the three White stones and making it easier to capture the cutting stone

) or does White have to play at “b” to keep Black stones on the bottom from coming to life? Unfortunately, White “a” seems impossible:
- Click Here To Show Diagram Code
[go]$$Wcm4 Prisoners: 
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . X O O O . . |
$$ | . . . . . . . . . . 1 O O O X O . X . |
$$ | . . . X . . . O . O . X X X X X O . . |
$$ | . . . X . O . . . 5 4 . . O . X O . . |
$$ | . . . . . . . . 7 6 . 8 . . 2 O 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Black group gets at least a ko for life, which is unacceptable for White. Thus, White has to play at “b.” However, Black then has a cornucopia of cutting points to try to exploit:
- Click Here To Show Diagram Code
[go]$$Wcm4 Prisoners: 
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . X O O O . . |
$$ | . . . . . . . . . . M O O O X O M X . |
$$ | . . . X . . . O . O 1 X X X X X O . . |
$$ | . . . X . O . . . . . . . O . X O . . |
$$ | . . . . . . . . . . . . . . M O M . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
In fact, Black can take immediate profit by playing

:
- Click Here To Show Diagram Code
[go]$$Wcm4 Prisoners: 
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . . . X . O . X O O . O . X . . O . . |
$$ | . . . X . X X X O . O X . . . X . O . |
$$ | . . . . . . . O X O X . . . . . . . . |
$$ | . . . X . . X X X O . . X . X X O . . |
$$ | . . . . . . . O O . . . . . . O . . . |
$$ | . . . . . . . . . X . . . X . . O . . |
$$ | . . . . . . . . . . . . . X O . . c . |
$$ | . . . X . . . . . O . . . O O X . . . |
$$ | . . . . . . . . . . . . X . X . . d . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . X O O O 2 . |
$$ | . . . . . . . . . . . O O O X O 3 X . |
$$ | . . . X . . . O . O O X X X X X O . . |
$$ | . . . X . O . . . . . . . O . X O . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White is forced to connect at

, so Black gains around 10 points (compared to if White played at

) and secures additional eye-space for his right group. Next, Black can play near the edge (at “c,” for instance) to secure eye-space for another eye or run into the center as in the game. Thankfully for White, it does not seem that Black can tenuki. If White plays at “d,” Black group does not have enough space for two eyes--at least based on the variations I looked at, so far. Therefore, White would be able to either deny Black’s group access to the center (helping White to create territory there) or else continue pressuring the two weak Black groups.
Here are some variations which show that White does not die immediately, despite the multitude of cutting points. First, if Black tries to save the bottom group, White proceeds in the following manner:
- Click Here To Show Diagram Code
[go]$$Bcm5
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . X O O O . . |
$$ | . . . . . . . . . . . O O O X O . X . |
$$ | . . . X . . . O . O O X X X X X O . . |
$$ | . . . X . O . . . . 3 4 5 O . X O . . |
$$ | . . . . . . . . . . . 6 . . 1 O 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
- Click Here To Show Diagram Code
[go]$$Bcm5
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . X O O O . . |
$$ | . . . . . . . . . . . O O O X O . X . |
$$ | . . . X . . . O . O O X X X X X O . . |
$$ | . . . X . O . . . . 5 3 . O . X O . . |
$$ | . . . . . . . . . 6 4 . . . X O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
- Click Here To Show Diagram Code
[go]$$Bcm7
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . X . . . . . . . . . . X O O O . . |
$$ | . . . . . . . . . . . O O O X O . X . |
$$ | . . . X . . . O . O O X X X X X O . . |
$$ | . . . X . O . . . . 4 2 3 O . X O . . |
$$ | . . . . . . . . . . 6 1 5 . X O O . . |
$$ | . . . . . . . . . . . 7 . 8 . . . . . |
$$ ---------------------------------------[/go]
Second, White does not need to fear an immediate cut at L5:
- Click Here To Show Diagram Code
[go]$$Bcm5
$$ | . . . . . . . . . X . . . X . . O . . |
$$ | . . . . . . . . . . . . . X O . . . . |
$$ | . . . X . . . . . O . . . O O X . . . |
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . 7 . . . X . . |
$$ | . . . . . . . . . . . 6 5 2 . X . . . |
$$ | . . X . . . . . . 8 . 4 3 X O O O X . |
$$ | . . . . . . . . . 9 1 O O O X O O X . |
$$ | . . . X . . . O . O O X X X X X O . . |
$$ | . . . X . O . . . . . . . O . X O . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
- Click Here To Show Diagram Code
[go]$$Wcm14
$$ | . . . . . . . . . X . . . X . . O . . |
$$ | . . . . . . . . . . . . . X O . . . . |
$$ | . . . X . . . . . O . . . O O X . . . |
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . X . . . X . . |
$$ | . . . . . . . . 5 8 7 O X O . X . . . |
$$ | . . X . . . . 3 4 O 6 O X X O O O X . |
$$ | . . . . . . . 9 2 X X O O O X O O X . |
$$ | . . . X . . . O 1 O O X X X X X O . . |
$$ | . . . X . O . . . . . . . O . X O . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Incidentally, White cannot play

at J5 as then the bottom group lives:
- Click Here To Show Diagram Code
[go]$$Wcm14
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . X . . . X . . |
$$ | . . . . . . . . . . . O X O . X . . . |
$$ | . . X . . . . . . O . O X X O O O X . |
$$ | . . . . . . . . 1 X X O O O X O O X . |
$$ | . . . X . . . O 7 O O X X X X X O . . |
$$ | . . . X . O . . . 6 4 5 . O . X O . . |
$$ | . . . . . . . . . . . . . . 2 O 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
- Click Here To Show Diagram Code
[go]$$Bcm21
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . X . . . X . . |
$$ | . . . . . . . . . . . O X O . X . . . |
$$ | . . X . . . . . . O . O X X O O O X . |
$$ | . . . . . . . . O X X O O O X O O X . |
$$ | . . . X . . . O O O O X X X X X O . . |
$$ | . . . X . O . . . X X O 1 O . X O . . |
$$ | . . . . . . . . . 5 4 2 3 . X O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
In the worst case scenario, if Black cuts at L5, White can always save himself by killing the bottom group:
- Click Here To Show Diagram Code
[go]$$Bcm5
$$ | . . . . . . . . . X . . . X . . O . . |
$$ | . . . . . . . . . . . . . X O . . . . |
$$ | . . . X . . . . . O . . . O O X . . . |
$$ | . . . . . . . . . . . . X . X . . . . |
$$ | . . . . . . . . . . . . 7 . . . X . . |
$$ | . . . . . . . . . . . 6 5 2 . X . . . |
$$ | . . X . . . . . . . . 4 3 X O O O X . |
$$ | . . . . . . . . . . 1 O O O X O O X . |
$$ | . . . X . . . O . O O X X X X X O . . |
$$ | . . . X . O . . . . . 8 . O . X O . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Naturally, this semedori is a solution of last resort. White would lose points (by having to place stones in his own territory) while Black would get to strengthen himself on the outside.
With all of the above remarks in mind, one may wonder whether

was a good move, an overplay, or a mistake. I’m not sure. It seems to me that, despite giving Black a chance to complicate the game and gain around 10 points in sente, White can hope to gain just as much or more from continuing to attack Black’s groups. That said, with the current game situation in mind--i.e. with White enjoying a solid lead--the safest way to play would have been to play

at S6. Black would need to respond to this so, after taking a profit of around 10 points in sente, White could proceed to invading Black’s left moyo. Nevertheless, taking the aspect of risk aside,

as played in the game might very well be a better move, objectively speaking.
This is why I chose to continue the attack with

. WS6 would be an admission of having made a mistake on the previous move and would result in a small loss for White coming from the exchange of

for

. May the conflagration of White’s attack be never extinguished!