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ladder-reading shortcut
http://www.lifein19x19.com/viewtopic.php?f=15&t=4926		 Page 1 of 1
Author:  frogola [ Tue Nov 01, 2011 8:21 am ]
Post subject:  ladder-reading shortcut
The trick I'm about to describe can save you much time spent reading long ladders.

Everyone knows that the star points on the goban are an aid for placing the handicap stones. However, these marked points can also be utilized as coordinates. Conveniently, they are placed in symmetrical positions on each side of the board.

Consider a stone which can be laddered. If that stone is on a star point, playing the ladder will force the stones to end up on the equivalent star point on the 90 degree side of the board. Corner star point stones end up on corner star points; side star point stones end up on side star points.

Try it -- it's true for any star point.

As a bonus, a stone on a corner star point is guaranteed to ladder directly onto the center star point.

As a corollary, whatever relation a laddered stone has with a star point will be replicated on the other side of the board. For example, a stone which is one space above the star point will, when laddered, end up one space above the star point on the target side of the board. This is true for all positions.

Intuitively this makes sense, since it's clear that ladders move diagonally and the board is a perfect square.

Once you understand this it becomes trivial to see where the ladder will end up. You don't have to sweat reading every move, and you save lots of time which can be spent on other strategic and/or tactical thinking.

It should be obvious that this tip applies to ladders which extend out toward the middle of the board, not ladders which extend to the edge. But inside ladders tend to be short and easy to read, so there is no need for further assistance.
Author:  hyperpape [ Tue Nov 01, 2011 8:23 am ]
Post subject:  Re: ladder-reading shortcut
Have you ever been hit with a book? Because someone on the forums (not me, mind you) is about to hit you with this one: http://www.amazon.com/Lessons-Fundament ... 906574289/.

Good thing for you that it's a paperback.
Author:  Chew Terr [ Tue Nov 01, 2011 8:28 am ]
Post subject:  Re: ladder-reading shortcut
hyperpape wrote:
Have you ever been hit with a book? Because someone on the forums (not me, mind you) is about to hit you with this one: http://www.amazon.com/Lessons-Fundament ... 906574289/.

Good thing for you that it's a paperback.


Haha, it took an almost physical effort for me to resist the urge. =D

To explain the joke, there is a chapter in that book essentially telling you never to use shortcuts in reading ladders. =)
Author:  Bill Spight [ Tue Nov 01, 2011 9:04 am ]
Post subject:  Re: ladder-reading shortcut
Not that frogola's tip is a bad one. To paraphrase contract bridge writer Victor Mollo, It's about seeing more than reading.

Have you ever heard a go player read out loud? "Here, here, here, here, . . ." ;)

That was not my experience when I was playing over daal's game that he lost in the endgame. Here is one thing that I saw: viewtopic.php?p=82119#p82119 I did not go through the motions of vicarious play, thinking White plays here, then Black plays here, etc. I saw the 7 moves at a glance, including one variation. I could also see that Black is dead in the final position, without going through the motions.

Not to denigrate careful reading, but the brain is a massively parallel processor with mostly unconscious operations -- thank goodness! To rely upon conscious, serial processing is second best. Exactly how did I see what I saw? I don't know. It happened unconsciously. Should I reject seeing because I did not have to work at it? Should I tie a hand behind my back?

frogola's tip is a shortcut. So is counting liberties. So what? Is reading out long but obvious ladders a valuable exercise? I don't know, I have never tried it. For shame, for shame! ;) Go is hard. I am for anything that makes it easier. :)
Author:  Chew Terr [ Tue Nov 01, 2011 9:20 am ]
Post subject:  Re: ladder-reading shortcut
That's certainly true, and I can definitely use the help, especially in times like byo-yomi.
Author:  jts [ Tue Nov 01, 2011 9:34 am ]
Post subject:  Re: ladder-reading shortcut
frogola - There's a thread on the forum called "post your ladders", where I've posted a bunch of ladder problems in an sgf. Can you go through it and tell me how many of the ladders in there your trick works on?

Bill - How many years of consciously reading out life and death went into that glance? :D
Author:  Bill Spight [ Tue Nov 01, 2011 9:59 am ]
Post subject:  Re: ladder-reading shortcut
jts wrote:
frogola - There's a thread on the forum called "post your ladders", where I've posted a bunch of ladder problems in an sgf. Can you go through it and tell me how many of the ladders in there your trick works on?

Bill - How many years of consciously reading out life and death went into that glance? :D


Oh, conscious reading can help seeing. :) As for my study of life and death, I think you know the story of how, as a 4 kyu, in a position like this one I found this brilliant endgame move:

Click Here To Show Diagram Code
[go]$$B Atari! (Dies in gote.)
$$ ---------------------------------------
$$ | . . . . . O X X 1 O O O . X X O . . . |
$$ | . . . . O . O X X X X X X X O . O . . |
$$ | . . . . . . O O O O O X X a O . . . . |
$$ | . . . , . . . . . O X X O . . , . . . |
$$ | . . . . . . . . . O O O O . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


;)

Edit: Something jogged my memory and I have edited the diagram. My thinking was that if White played at "a" the result would be seki, so I had to seize the opportunity to capture the White stones. :oops:

Out of curiosity, a couple of years ago I tried to figure out how many tsumego I have worked on. It's around 300. :)
Author:  daal [ Tue Nov 01, 2011 10:15 am ]
Post subject:  Re: ladder-reading shortcut
Bill Spight wrote:
Out of curiosity, a couple of years ago I tried to figure out how many tsumego I have worked on. It's around 300. :)


300? :o What exactly did you do when you "worked on" a tsumego?
Author:  Marcus [ Tue Nov 01, 2011 10:50 am ]
Post subject:  Re: ladder-reading shortcut
Bill's variation in the corner in daal's game is one that jumps out at me as well, for what it's worth.

I'm also curious about what Bill means concerning working on tsumego. I mean, if he means trying to solve them I've only really worked on maybe 50-100 myself ... but I simply don't study enough (and my weakness shows it)!
Author:  Bill Spight [ Tue Nov 01, 2011 11:31 am ]
Post subject:  Re: ladder-reading shortcut
daal wrote:
Bill Spight wrote:
Out of curiosity, a couple of years ago I tried to figure out how many tsumego I have worked on. It's around 300. :)


300? :o What exactly did you do when you "worked on" a tsumego?


Spent at least two minutes trying to solve. :)

Sometimes I used to carry one of the Maeda trilogy with me on the subway and work on a couple of problems during the ride.

As a 4 dan I used to take an hour to work on 4 problems, at 15 min. per. Most of those were not tsumego problems, though.
Author:  snorri [ Tue Nov 01, 2011 2:10 pm ]
Post subject:  Re: ladder-reading shortcut
Bill Spight wrote:
Out of curiosity, a couple of years ago I tried to figure out how many tsumego I have worked on. It's around 300. :)


And if you count the ones that are implied in games...? :)
Author:  Solomon [ Tue Nov 01, 2011 3:18 pm ]
Post subject:  Re: ladder-reading shortcut
This video pretty much sums up how I feel when I use the trick instead of reading it out. Takes a while to get used to.
Author:  Bill Spight [ Tue Nov 01, 2011 3:23 pm ]
Post subject:  Re: ladder-reading shortcut
snorri wrote:
Bill Spight wrote:
Out of curiosity, a couple of years ago I tried to figure out how many tsumego I have worked on. It's around 300. :)


And if you count the ones that are implied in games...? :)


That's why I go for big territories. ;)
Author:  cyclops [ Tue Nov 01, 2011 4:52 pm ]
Post subject:  Re: ladder-reading shortcut
Araban wrote:
This video pretty much sums up how I feel when I use the trick instead of reading it out. Takes a while to get used to.

I hope you use a different strategy in your current game against MW.
I admit I also use shortcuts when reading ladders. Another one for me is that a ladder just won't pass through between two adjacent hoshi stones like shown here:
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . X . . . . . X . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |[/go]
Author:  Bill Spight [ Tue Nov 01, 2011 5:40 pm ]
Post subject:  Re: ladder-reading shortcut
jts wrote:
There's a thread on the forum called "post your ladders", where I've posted a bunch of ladder problems in an sgf. Can you go through it and tell me how many of the ladders in there your trick works on?


I skimmed through the file, and found that a shortcut could be helpful in most of the cases. E. g.,

Click Here To Show Diagram Code
[go]$$B Can Black to play escape the ladder?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X . . O . |
$$ | . . X O . O O O O . . . X . X O O . . |
$$ | . X . O . . X X . , . . . O O X X O . |
$$ | . X X . . . . . . . . . X . X X . . . |
$$ | . O X . . . . . . . . . . . . . O . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . O X O . . |
$$ | . . O O . . . . . . . . . . . O X X . |
$$ | . . X O . . . . . . . . . . . . O X . |
$$ | . . X , . . . . . , . . . . . O . X . |
$$ | . . . X . X . . . . . . . O . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


My shortcut. Note the relation of the ladder to the star point. Then visualize the ladder shifted to the same relation to the diagonal star point.

Click Here To Show Diagram Code
[go]$$B Can Black to play escape this ladder?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X . . O . |
$$ | . . X O . O O O O . . . X . X O O . . |
$$ | . X . O 7 5 X X 2 , . . . O O X X O . |
$$ | . X X . 8 6 4 3 1 W . . X . X X . . . |
$$ | . O X . . . . W B W . . . . . . O . . |
$$ | . . O X . . . . W . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . O X O . . |
$$ | . . O O . . . . . . . . . . . O X X . |
$$ | . . X O . . . . . . . . . . . . O X . |
$$ | . . X , . . . . . , . . . . . O . X . |
$$ | . . . X . X . . . . . . . O . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I actually read up to :w4: and saw the rest. Visualizing the ladder saved reading 28 moves. :)
Author:  frogola [ Tue Nov 01, 2011 5:58 pm ]
Post subject:  Re: ladder-reading shortcut
I take no responsibility for your results [YMMV] and initially it may be a bit scary to use, but when I figured out this technique I thought it was too cool not to share. The biggest problem as I see it is when intervening stones are near the path and you don't realize.

Of course there's no substitute for reading, but there are a large number of cases where this technique saves time.
Author:  Bill Spight [ Tue Nov 01, 2011 6:55 pm ]
Post subject:  Re: ladder-reading shortcut
Another example:

Click Here To Show Diagram Code
[go]$$W Can White to play capture the marked Black stones in a ladder?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X X X . . . . . . . . . . . . |
$$ | . . X X O O X O X . . . . . . . . . . |
$$ | . . X O X O O X . , . . . . . , X . . |
$$ | . . O O . . O X . . . . . . . . . . . |
$$ | . . . . . . O O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . O . . . . . . . . . . |
$$ | . . . . O X . . . . . . . . . . . . . |
$$ | . . . , . . . . O , . . . . . , . . . |
$$ | . . . . . X O . . . . . . . . . . . . |
$$ | . . O . . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . X O B B . . . , . . . . . O . . . |
$$ | . X X X O O . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Well, it certainly looks like Black has a ladder breaker in the top right corner. Here my shortcut involves shifting it, as well.

Click Here To Show Diagram Code
[go]$$W Can White to play capture the marked Black stones in a ladder?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X X X . . . . . . . . . . . . |
$$ | . . X X O O X O X . . . . . . . . . . |
$$ | . . X O X O O X . , . . . . . , X . . |
$$ | . . O O . . O X . . . . . . . . . . . |
$$ | . . . . . . O O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . O . . . . . . . . . . |
$$ | . . . . O X . . . . . . . . . . . . . |
$$ | . . . , . . . . O , B . . . . , . . . |
$$ | . . . . . X O . W . . . . . . . . . . |
$$ | . . O . . X . W B B . . . . . . . . . |
$$ | . . . . . . . . W W . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . X O X X . . . , . . . . . O . . . |
$$ | . X X X O O . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


A quick look reveals that we can even shift the ladder one space towards the top of the board, and Black still has a ladder breaker.

Hmmm. Perhaps we can make use of the White stones near the main path of the ladder. Let's back the ladder up one step and see.

Click Here To Show Diagram Code
[go]$$W Can White to play capture the marked Black stones in a ladder?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X X X . . . . . . . . . . . . |
$$ | . . X X O O X O X . . . . . . . . . . |
$$ | . . X O X O O X . , . . . . . , X . . |
$$ | . . O O . . O X . . . . . . . . . . . |
$$ | . . . . . . O O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . O . . . . . . . . . . |
$$ | . . . . O X . . . . . . . . . . . . . |
$$ | . . . , . . . . O , B . . . . , . . . |
$$ | . . . . . X O . 4 5 . . . . . . . . . |
$$ | . . O . . X . W 2 3 . . . . . . . . . |
$$ | . . . . . . W B B 1 . . . . . . . . . |
$$ | . . . . . . . W W . . . . . . . . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . X O X X . . . , . . . . . O . . . |
$$ | . X X X O O . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I just saw that one. :)
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