Ladder / Reading Techniques

Sub-page of Ladder

This page discusses various ideas to simplify reading ladders but also presents the view that you should always read the full ladder.

Table of contents Table of diagrams
[Lessons in the Fundamentals of Go] Diagram 1
Ladder-breakers and failures
Ladder-breakers near the corner
Ladder-breakers in the corner
Not a ladder-breaker 1
Not a ladder-breaker 2
Ladder width
Ladder-breaker points
Reading the zig-zag
Diagonal + direction
Shift along hoshi points
Counting from the hoshi
Assume "o" as blue circle
Ladder Exercise 6
Can white escape ?

The Professional view: read fully

Kageyama Toshiro states emphatically in Lessons in the Fundamentals of Go

The outcome of the game hangs on whether or not Black can capture the white stone in the ladder that starts with B1. Many amateurs, sometimes even dan-ranked players, are apt to become impatient when confronted with long ladders like this and resort to stooping down and sighting diagonally or running their fingers zig-zag across the board, or in extreme cases to arguing their opponents into submission verbally. All this I find a bit silly.

When a ladder becomes slightly difficult to read like this, there is a widespread tendency to give up, and wonder if there is not something like a triangle theorem, some mechanism one can apply to get the answer instantly. If you want to create such a thing it is not too much trouble to do so, but having it will only prove destructive to your game. Ladders are the school that teaches you to read patiently, move by move, — black, white, black, white, black, white — which is the only way.

... Confine your practice to this one exercise every day until you can read the long-distance ladder in Diagram 1 with the greatest ease, right out to its end. When you can do that, rearrange the stones in the lower left corner — use your ingenuity — and try reading again. That's the way.

This exercise will earn you a valuable reward: the confidence that you can read any ladder anywhere, anytime. This confidence heralds your next big stride.

See Practising Reading Out Ladders.


Ladder-breakers on the first 3 lines

When a possible ladder breaker is close to the edge, remember that the attacker can give atari in two ways. This means that some apparent ladder-breakers do not work.

Ladder-breakers and failures  

In this diagram, a black stone at any point marked b is a ladder breaker, but those marked f fail.

It is a good exercise to work out why these points do or do not break the ladder — one case is worked out below.

Note these rules:

  • There are 6 diagonals of ladder breakers.
  • The 1-2-4 rule: on the 3rd, 2nd and 1st lines respectively, 1, 2 or 4 outside diagonals fail.

Ladder-breakers in the corner

Ladder-breakers near the corner  

When the defending stones miss the corner by 1 line, the previous diagram is still valid, with one spot removed.

Ladder-breakers in the corner  

Even when the defending stones run right into the corner, the pattern holds, with 3 spots removed.

Moving the pattern up one more line effectively reflects it in the diagonal of the board, yielding the same position with the ‘outside’ now in the West instead of the North.

A failed ladder breaker on the second line

Not a ladder-breaker 1  

Why is black+circle not a ladder-breaker?

Not a ladder-breaker 2  

This diagram shows why: on the second line, White can play at W15 instead of a in the diagram, rendering the black+circle stone useless.

Is the attacker forced to play a ladder?

A ladder in the broader sense is an attacking sequence where the defender can never get more than two liberties and the attacker repeatedly plays atari until they capture.

When some of the attacker’s surrounding stones have only two liberties, and they cannot be sacrificed, the attacker is forced to play a ladder to capture. In the typical staircase shape running through open space, even if the attacker’s original stones had more liberties, they rapidly reach a position where several of their stones offer possibilities for double atari. Normally that makes the ladder collapse; in this case the attacker is also forced into a ladder.

When the attacker is forced into a ladder, this somewhat simplifies the reading, because one only need consider ataris which only allow the defender to gain one more liberty by running away.

Check both ataris

Extending the lesson of the section about ladder breakers and the second line, when reading a ladder, always consider both ways to give atari. In open space, with the typical staircase type of ladder, one atari lets the defender get three liberties; if the attacker is forced to play the ladder, they have to play the other atari, maintaining the characteristic zig-zag.

At the edge of the board, however, we saw above that the attacker has two ways to finish the ladder, invalidating some ladder breakers.

Similarly, when a ladder reaches pre-existing stones, both ataris may only allow the defender to gain one more liberty. In such cases, one has to read both variations.

Visualise non-verbally but rhythmically

Tapir: While I don't use any shortcut I would like to share an experience I made. I used to read "If Black plays here, White plays here, Black plays here etc." that is I verbalized while reading. I read slowly and inaccurately then. Now I try to visualize. Since visualizing isn't so easy over the whole board I now try to visualize with rhythm — that is "Atari, extend", "Atari, extend" — without thinking the words or verbalizing of course. I admit the ladder here is still somewhat difficult to read — I lost track several times :) — but even that is readable.


Note: This section contains suggestions that are somewhat controversial. Some people[1] believe that these are injurious to your playing ability.

The ladder-breaking region

Ladder width  

It is useful to note that the width of a ladder is four stones (horizontally or vertically). Because any opponent stone at the adjacent circle points will also break the ladder, the region of the board that affects the ladder is actually six points wide. If there aren't any opposing stones in that area, a ladder works.

PJT: I think that as long as stones are clearly outside this region there is no need to read the ladder, and that this shortcut is harmless — but of course you have to check carefully.

Ladder-breaker points  

A simple technique for reading a ladder is to visualise six diagonal lines from the start of the ladder. Except for a, b and c, any black stone (on its own) on the marked points will make a ladder-breaker.

However, if there are both black and white stones in the marked region, please read the ladder 'manually': visualise it on the board. That's not so hard, either.

Only read the zigzag

uxs: I agree. Being able to read them out is more useful than this "simple" technique, which apparently doesn't even work when there are just a few stones in the way. On the other hand, reading them out can be hard, especially if you try to read them as "black, white, black, white, ..." You just tend to lose track after a while.

I have found that the following works rather well: instead of reading out all stones, just read the inside stones, until you come across possible ladder breakers. In other words, if it's black chasing white stones, read the white ones. This is very easy, since it's just a simple zig-zagging across the board. Then as you come across the possible breaker stones, add (in this example) the black stones. This is also easy, as you just have to add one in the direction where you read the last white stone.

Reading the zig-zag  

In the example, the initial situation is all the unmarked stones. When you start reading, you only read out the (marked) white stones. When you then come across the possible ladder breaker, you also read the black ones. You can stop reading when you see that W5 puts B2 in atari.

(Actually, you could've already stopped reading at B2, since it touches the white stone below it and will therefore surely be put into atari. But it's safer to actually read it completely, and not that much more difficult.)

Read only one diagonal

Instead of reading only the zig-zag (as in the previous shortcut), you can visualise just one diagonal until you reach a possible ladder-breaker, and then reconstruct the rest of the ladder. You can choose one of four possible diagonals, two of each colour.

Diagonal + direction

QWerner: I think using the correct reading technique for ladders is important, because these are reading examples which can go thought the whole board. If you are under time pressure and you start to read the whole ladder out its easy to miss a line. Even by reading only the zig-zag.

I do it the following way:

Diagonal + direction  

B1 will be right of the last red circle and the next W stone is then under the red circle, because the first two W stones are vertical.

Shift the ladder diagonally (Hoshi points help)

The professional Guo Juan, in her Internet Go School, also suggests the shifting methods in this and the next section.[3]

ColdNightHere is a trick I figured out myself. You might find this useful when choosing Joseki: Instead of reading all the way to the corner, simply move the stone in your head to its place next to the Tengen to cut the reading in half.

Shift along hoshi points  

Tapir: Imo, this is the only shortcut which is not self-defeating / self-cheating. However, how long do you need to read a ladder out to tengen and to the other side of the board. I may need a similar time to move the stones in my head. Though a shortcut for blitz games may well be helpful.

Counting from the hoshi  

Timm: I feel like reading the zigzag throughout the board is fastidious and error-prone. Instead, in such a case, I'd just note that “White starts moving to the left on the second point from the hoshi” and jump to the end of the ladder.

This works well in the most simple cases. Then if at first glance it seems it won't be trivial to use the hoshis, I'd just expand the zigzag and read the last moves.

Shift the obstacle diagonally

Instead of the previous method (visualise the ladder shifted towards the obstacle), one can visualise the obstacle shifted towards the ladder. When the obstacle is a single stone, it is much easier to imagine that placed close to the ladder, and the hoshi points are especially helpful.

Bear these points in mind:

  • In general, you need to mentally shift the edge of the board as well as the obstacle, otherwise you could misread some cases, such as a single stone on one of the first 3 lines. (See the section on ladder breakers on those lines)
  • For a single (defender’s) stone, you need only consider the stone itself if you follow these rules, based on the section mentioned.
    • Shift the stone diagonally until it reaches the ladder. It is a ladder breaker in these cases only:
      • It must eventually make contact with a stone in the ladder, AND
        • It (in its original position) is on the fourth line or higher. OR
        • It (in its original position) is on the 3rd, 2nd or 1st line and not excluded by the 1-2-4 rule, i.e. not on the one of the outside 1, 2 or 4 diagonals respectively.

Shift the simpler position

Given that it is possible to shift the obstacle towards the ladder or vice versa, it seems sensible to shift the simpler position.

If both positions are hard to shift, it is evidently time for full reading!

External aids

Here is a space for tools or techniques that go beyond one’s own internal thought processes.

For completeness, we can include the ideas disparaged in the introductory quote from Kageyama Toshiro: squinting along diagonals, using one’s finger, brow-beating the opponent(!).

Checkered goban

The user hnishy has a nice suggestion on his home page: a checkered pattern on the goban could make ladders easier to read:

Assume "o" as blue circle  


[1] Kageyama says: No shortcuts. Read the ladder. Always. See Practising Reading Out Ladders.

[2] Once again, if you can avoid the confusion — I used to get confused when the ladders got messy and would switch to per-move... It's the same thing only it's slightly more time consuming as you save some time by landing both the inner ladder stone and the pressing one when u'r only reading the zig-zag...

[3] For subscribers to her school, see the lecture [ext] Basic course – Topics – 17 – Ladder – Reading ladders (lesson id 1020)


Ladder ethics

Originally started as comment to “read the zig-zag”, but of general interest.

Klaus: In my humble opinion, all these tricks are going the wrong way. Just Read the ladder!!

"I heard from my teacher that whoever has contrivances with tricks to make them go is sure to have activities with tricks to make them go. Whoever has activities with tricks to make them go is sure to have a heart with tricks to make things go. If a heart with tricks to make things go is lodged inside your breast, the pure and simple will not be at your disposal. If the pure and simple is not at your disposal, the daemonic and vital will be unsettled. Anyone in whom the daemonic and vital is unsettled, the Way will not sustain. It isn't that I don't know, it's that I would be ashamed to make it."

(see: Graham, A.C.: Chuang-tzu: the seven inner chapters and other writings: page 186 from the book Chuang-tzu, Unwin Paperbacks, London,1986.)

uxs: If you're saying that the way I read them is a trick, I have to disagree. You ARE reading them out, but only the relevant parts.

Klaus: So the trick is leaving out the irrelevant parts? I guess it is a matter of patience to read out all moves, one by one. It might not seem to be necessary, but it is the right spirit. (Yes this is the part of eastern philosophy which western people have most problems with, and well, I might be off the mark, who knows?)

kevinwm: Hey man — don't make it a big black and white thing! That's really messing with the Tao. You can pay closer attention to some of the stones, but don't completely forget the other ones either. In case the ladder comes back and intersects with itself later... can you read this?

Ladder Exercise 6  

(see Ladder Exercise 6)

Bob McGuigan: uxs mentioned a tendency to lose one's place when reading out long ladders move by move. That prompted me to think that that is exactly why one should read them out that way. The larger goal is not to determine whether the ladder works but to strengthen the ability to concentrate and read, ladders being a relatively simple training ground.

Not really a trick, I think that uxs does well by saving time... Anybody who sees the zig zag can see it wrapped. Just as long as you're careful and don't get confused... And ladders aren't the easiest way to practise reading — They can be hard (/confusing) for stronger players as well... Reuven

Kageyama recommends reading ladders all the way across the board every day till it becomes easy. Then throw a few stones in the way and do it again, daily, till it becomes easy. I would add, repeat till the ladder problems in The Treasure Chest Enigma become easy. Any else is shortcutting your own ability to read and to visualize. See Lessons In the Fundamentals of Go Just last night at go club, a person(4k) that used to beat me reguarly played into a ladder that i had already read out. THEN started to read the ladder which extended three-quarters of the way across the board. One could see his head nodding move by shock I exclaimed "now you start reading the ladder!" This is not the first time this has happened this year. Beat a different 4k the same way several months ago. Note to self: Read ladders till they are so easy, you dont hesitate to do so. Ever. Velobici

Reuven: Hmmm I really don't understand the difference — It's not a shortcut! the zigzags aura (:) is as obvious as an elementary problem would be to you. You don't really read it, it's just there — You only pay attention to the zig zag itself until anything else is called for if you can...[2]

More realistic example

This position was given as an example where tricks do not help, and you are forced to read the entire sequence. See /Example for the ensuing discussion

Can white escape ?  

Ladder / Reading Techniques last edited by PJTraill on February 13, 2023 - 01:14
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