crux wrote:
jts wrote:
Ed makes a rule of pointing out broken shapes in joseki.
Yes.. I find this obsession about a single shape issue a bit strange.
Glad it's not just me then

. Whilst it is true that making broken shapes is a very common beginner mistake, and if they were to magically stop making such shapes instead of always making them they would play better, as with all proverbs/principles etc. there are exceptions (particularly if you apply such a superficial broken shape pattern detector) so they would play even better if they sometimes make them, aware that they are doing so but having a good reason to. I seem to recall Ed has labelled (and thus criticised?) that joseki example as a broken shape. But that misses a very important point about that joseki, namely that white's initial approach stone causes black to
connect in bad shape. Were that stone not there, black would defend the cut with a hanging connection. This is a good shape with good eye potential, the wall is strong:
- Click Here To Show Diagram Code
[go]$$B Strong wall with eyes
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . O O O . O . . . .
$$ | . O X X X . . . . .
$$ | . X . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .[/go]
In the joseki, the white stone has a lot of aji and at a later point, particularly with a supporting stone at
a, white can put the stone in motion at 1 (oh no! another broken shape!) and not only stop black making territory here, white can often have an attacking element against the eyeless black wall (as well as being under attack himself, that's what fighting is all about).
- Click Here To Show Diagram Code
[go]$$W Weak eyeless wall
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . O O O . O . . . .
$$ | . O X X X . . . . .
$$ | . X X . . . . . . .
$$ | . 1 O . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . . . . . . . .
$$ | . . a , . . . . . .
$$ | . . . . . . . . . .[/go]
On the topic of the broken shape at move 36, I agree with tapir/crux that the whole corner joseki sequence was not a good choice given the whole board situation (in fact I think maybe L4 was too far and something closer to the corner like q5 shimari or n4 would be better), but talking locally about the broken shape Ed asked, presumably rhetorically as an implicit criticism, "What is the (a) stone doing?" Well, seeing as (a) was a good move in that sequence there is an answer, and that answer is "It forces white to connect where he is already connected and prevents q7 from being an eye. It also makes it harder for white to attach at q9 which would get out into the centre in nice shape and could build an eye at q8". s8 is a good move for black to reduce the eyespace of the white group and make profit whilst attacking, but if you don't play the push and peep first then white can play q9 to come out nicely. Here's a somewhat silly sequence for black that shows if you try to push/peep too late then white just cuts off the stone and makes an eye, instead of connecting at q7. Obviously this sucks for black, but even sensible moves like 3 at q10 aren't great.
- Click Here To Show Diagram Code
[go]$$c If you peep too late white won't connect
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 7 . . |
$$ | . . . . . . . . . . . . . . 8 2 X . . |
$$ | . . . . . . . . . . . . . . . 5 6 1 . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . . X 3 4 . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . , . . . . . , X . . X . , O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
In fact if black gets to play s8 that is rather nice for him, so white usually does not connect against the peep immediately but attaches at s9 to enlarge his eyespace in sente (the group is now locally alive, even if it gets sealed in), but at the cost of strengthening black in the upper right.
- Click Here To Show Diagram Code
[go]$$c More eyespace before connecting
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 7 5 . |
$$ | . . . . . . . . . . . . . . . . X 4 . |
$$ | . . . . . . . . . . . . . . . 3 . 6 . |
$$ | . . . . . . . . . . . . . . O 8 O . . |
$$ | . . . . . . . . . . . . . X 1 2 . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . , . . . . . , X . . X . , O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
This attachment is also a sort of probe (but with only one sensible answer for black), because if black cuts off the stone with the inside hane, then white gobbles the peep stone instead of connecting. If white connected first (and then black tenukid) and then white played s9 black could consider hane inside as then q7 becomes a wasted move.
- Click Here To Show Diagram Code
[go]$$c Don't need to connect
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 9 7 . |
$$ | . . . . . . . . . . . . . . 0 8 X 4 . |
$$ | . . . . . . . . . . . . . . . 3 6 5 . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . . X 1 2 . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . , . . . . . , X . . X . , O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
I suppose the key thing about the ripped keima broken shape which makes it bad is when the two separated black stones are not yet separated, but you force white to separate and damage them both (such as move 44). In the move 36 example the two black stones are already separated (by p7) so white's move at q7 does not hurt them any more than they were already (which was not much) and in fact is itself inefficient in connecting where white was already connected (and loses eye potential and makes q9 harder as described above).
Staying on the theme of broken shapes I am reminded of a rather brilliant move that Guo Juan 5p found during a reivew of a game of mine (full record at
http://homepage.ntlworld.com/andrew.j.s ... fadyen.sgf). The question in the position below was is the top-side white's territory? I wasn't confident I could live in there (and was ahead even if I didn't) so just planned to play m18 sente yose (actually I forgot to do even that!), but Guo said that was too kind and I should be able to find something better. 3-3 in the top left doesn't live, but there should be a way to combine that corner with the wideness of the top side to find an invasion. After some thought, Guo found the following beautiful sequence (if 2 doesn't block the corner but pincers on the side then 3-3 lives without too much trouble). Black 3 creates the classic broken shape and is a move I would never dream of, but here it builds eyespace in sente and it doesn't matter that the corner is damaged a bit as white's top-side territory is trashed.
- Click Here To Show Diagram Code
[go]$$Bc Simplified position
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 2 . 1 . . . . 7 5 6 . . . . . . |
$$ | . . . . . . . 9 . . 3 4 8 . O X . . . |
$$ | . . . O . . . . . , . O X X X , X . . |
$$ | . . . . . . . . . . . O O O O X . . . |
$$ | . O O . O . . . . . . . . . X O . . . |
$$ | . . X X O . . . . . . . . . . O . . . |
$$ | . O O O X O . . . O . . . O . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |[/go]
In fact as I write this I have just realised that a very similar broken shape tesuji was suggested by Mateusz Surma 6d for a game I played recently.
- Click Here To Show Diagram Code
[go]$$Wc What I (white) played
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . X . . . . 9 X . . . . . . O . . . |
$$ | . . . , 7 X . . . X . O . . . , . . . |
$$ | . . . 8 2 1 5 O . . X O . . . O . . . |
$$ | . . . 6 3 4 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
I wanted to save my h3 stone so played the f3 attachment and counter hane which is a fairly standard sabaki idea, but black just took profit and although I just managed to live my play was rather heavy. Instead Mateusz suggested the same inside "armpit hit" as Guo's 3 to sacrifice h3, make a broken shape and take the corner instead (and aim at d5 weakness later):
- Click Here To Show Diagram Code
[go]$$Wc Sacrifice better.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . X . . . . . X . . . . . . O . . . |
$$ | . . . , . X . . . X . O . . . , . . . |
$$ | . . 7 . 1 2 6 O . . X O . . . O . . . |
$$ | . . . . 5 3 4 . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
This shape still feels unnatural to me so I am not sure I will be able to find it in my future games. To do so I need to unlearn my 'don't play broken shapes' instinct (and be more willing to sacrifice).
And to finish, here is a problem from a game of mine where the winning move combines broken shape, squeezing the toothpaste and an empty triangle to create what must be one of ugliest tesujis I've ever played.
- Click Here To Show Diagram Code
[go]$$c White to play and make your eyes bleed
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X . X . X X O O . . . . . . . . . . |
$$ | . . X O X X O X X O . . O O . O O O . |
$$ | . O . O O O O . X O . . . X X X X O . |
$$ | . . O . . . . . X O . . . . . . X X . |
$$ | . O X X . . . . X X . . . . . . O . . |
$$ | . . O X . O O . . . . X . . . . . . . |
$$ | . . O X . X O X X X O . X . . . X . . |
$$ | . . . . . X O X O O . O B O . . . . . |
$$ | . . X X . . . O X , . . O X X , . . . |
$$ | . O O O X X O O X . X . O O X X . . . |
$$ | . . X O O X . . X . . . O X . X . . . |
$$ | . . O X . . . . . . . . O X . O X X . |
$$ | . . O . . . . . X . O . O O . O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . O . . X . O O . O O . . . |
$$ | . . . . . X . O . . X X . X X X X . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Answer:
Phew! Time for bed!