[go]$$B
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . O O O O O O
$$ | . X X X X X X
$$ | . . . . . . .
$$ | . . . . . . .[/go]
Re: Does this have a name?
Posted: Sun Feb 24, 2013 5:33 am
by PeterPeter
I think I am OK with the 1 point gap.
The first time I came across the 2 point gap, I dived straight in with, "If one hane is good, double hane must be better". It did not end well.
Re: Does this have a name?
Posted: Sun Feb 24, 2013 5:45 am
by Amelia
PeterPeter wrote:The first time I came across the 2 point gap, I dived straight in with, "If one hane is good, double hane must be better". It did not end well.
Yeah
There are other nasty things to consider, like for example this one (if one of the players descends and the other does not): http://senseis.xmp.net/?MonkeyJump
Beware of it. Our fellow DDKs love this tesuji, as it is simple to remember and can eat quite a bit of enemy territory in the endgame.
Re: Does this have a name?
Posted: Sun Feb 24, 2013 6:09 am
by PeterPeter
Monkey jumps are great fun if your opponent allows you to do one, but assuming they reply properly and close it off, it feels like there should be something better available than allowing it to become Ed's position:
$$B
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . O O O O O O
$$ | . X X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
[go]$$Bc
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | c 2 d . . . .
$$ | a 1 O O O O O
$$ | . b X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .[/go]
That's why extending downwards to 'a' is not good in most cases because the cutting point at 'b' remains. So any play from White at 'c' is forcing you to defend at 'b' if you don't want to lose your stones. In other words you turn 'c' into Sente for White, which is generally unwanted in the endgame. If this border on the other hand is the last play on the board then descending to 'a' is the correct play because it will give you one more point compared to just connecting at b.
$$Bc
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | 4 2 a . . . .
$$ | 3 1 O O O O O
$$ | . b X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
[go]$$Bc
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | 4 2 a . . . .
$$ | 3 1 O O O O O
$$ | . b X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .[/go]
Note that 'a' never works after you extended downwards. White just plays 'b' and captures your stones. It's two liberties for White against one liberty for you.
Since we mentioned Sente in the endgame: In my experience in most cases Black will want to play like this because he can keep Sente while finishing off this border (depends of course on the whole board, e.g. the remaining endgame). If White does not answer , Black can play at or monkey-jump at 'a', which is big.
$$Bc
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | a . . . . . .
$$ | 4 6 . . . . .
$$ | 3 2 O O O O O
$$ | 5 1 X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
[go]$$W
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | W W . . . . .
$$ | B B O O O O O
$$ | 5 1 X X X X X
$$ | 3 2 . . . . .
$$ | 4 6 . . . . .
$$ | . . . . . . .[/go]
Because White threatens this capture. If captures at 5, takes back at 1. That is called a snapback. The position after the exchange of the and stones is better for White than the original position, because in the original position White cannot continue with . That is why Black needs to connect with in the previous diagram. If he doesn't he has just lost points for nothing.
Compare these positions.
$$B
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
$$ | W O . . . . . _ . . . . . X . |
$$ | B X O O O O O _ X X X X X O . |
$$ | . B X X X X X _ O O O O O W . |
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
$$ | . . . . . . . _ . . . . . . . |
[go]$$B
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . 2 . . . . .
$$ | a 1 O O O O O
$$ | c b X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .[/go]
Now. What about "c"?
Re: Does this have a name?
Posted: Sun Feb 24, 2013 10:44 am
by Uberdude
SoDesuNe wrote:For me the natural follow-up to a Hane on the second line is connecting,
That's because you are not a beginner. It is a very common beginners mistake, indeed perhaps what the majority do. I know that when I was a beginner I did it too*. Probably because to the beginner eye it looks like you are getting a bigger area than with the solid connect. But that's overlooking the sente gain/loss that can happen later so actually it is smaller.
* Actually looking back at my DDK games on KGS it seems I was a big fan of the 1st line hanging connection, which in general terms** is not as bad as the descent, but worse than the solid connection.
** There are of course certain situations in which the 1st line descent, 1st line hanging connection, 2nd line solid connection, and 2nd line hanging connection are the best move.
Re: Does this have a name?
Posted: Sun Feb 24, 2013 10:59 am
by Bill Spight
Uberdude wrote:
SoDesuNe wrote:For me the natural follow-up to a Hane on the second line is connecting,
That's because you are not a beginner. It is a very common beginners mistake, indeed perhaps what the majority do. I know that when I was a beginner I did it too*. Probably because to the beginner eye it looks like you are getting a bigger area than with the solid connect. But that's overlooking the sente gain/loss that can happen later so actually it is smaller.
* Actually looking back at my DDK games on KGS it seems I was a big fan of the 1st line hanging connection, which in general terms** is not as bad as the descent, but worse than the solid connection.
** There are of course certain situations in which the 1st line descent, 1st line hanging connection, 2nd line solid connection, and 2nd line hanging connection are the best move.
When I was a beginner I recoiled from the descent. But I was confused about whether to play the solid connection or the hanging connection. It turns out that, when it is not a matter of tactics, the hanging connection is dominant, unless the difference in ko threats matters. It will rarely matter, but I think that the gain regarding ko is both more frequent and larger than the gain from preventing the hane-and-connect.
Re: Does this have a name?
Posted: Sun Feb 24, 2013 8:12 pm
by Phelan
PeterPeter wrote:From this position:
$$B
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . 2 . . . . .
$$ | a 1 O O O O O
$$ | . b X X X X X
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
[go]$$B
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . 2 . . . . .
$$ | 3 1 O O O O O
$$ | . . X X X X X
$$ | . 4 . . . . .
$$ | . . . . . . .
$$ | . . . . . . .[/go]
This doesn't work here, but if there's weakness on the lower part, this peep might be a lot of trouble. It's rarer than what has been shown so far, but it's another reason why I usually prefer to play the solid connection.
and 
.
and 
.
or monkey-jump at 'a', which is big.
captures at 5, 
takes back at 1. That is called a snapback. The position after the exchange of the 
and 
stones is better for White than the original position, because in the original position White cannot continue with 
. That is why Black needs to connect with 
in the previous diagram. If he doesn't he has just lost points for nothing.