L+1 with two hane

[Kirby]

Very common shapes are practical to know since they enforce knowledge of the shape, and it'll be easy to deal with in your game.

Practicing the art of searching for a solution to a less common shape has value, too, because you will see many non-common shapes in your games. It may not be this particular "less-common" shape, but getting good at iterating through the unknown is undoubtably valuable.

To give an analogy, it's very practical to learn multiplication tables to get good at multiplying. You'll often have to multiply single digit numbers, such as 7x6 or 9x3. But it's also important to practice multiplying larger numbers, too. You probably won't often have to multiply 358x147, but you need to practice the process of multiplying uncommon numbers. That particular uncommon set of numbers may not be something you have to multiply on a regular basis, but you'll surely have to multiply other uncommon numbers, and you need to practice doing it.

[oren]

Can I see this example? Do I assume the Japanese player kept passing when the Chinese player filled the dame and won the game he should have lost?

I could only really imagine seki or komi issues. Japanese players fill dame at the end to score. They're just not kept in the game records.

[Bill Spight]

So? How many tsumego problems come up in real games? Moi, I think that it is good to understand corner play.

I was asking a question (how important is this?), not making a statement. There were two things behind this. One is that certain corner positions do come up an awful lot in actual play, and the commonest may well be the carpenter's square. That may in turn be why pros keep telling us that mastery of the CS indicates you are 5-dan, which I take to be a PR way of saying the CS is common and therefore important - or at least more important than the L+1 + 2 hanes.

Gee, what I heard was that mastery of the capenter's square indicated shodan strength. Evidence of rank inflation?

The second thing is that I've experienced many times cases where even dan players come up against things like yose-kos, double kos, mannen-kos and don't know how to handle them. I presume they've made a previous conscious decision not to study these things because they are relatively rare.

I remember a yose ko occurring in a game once, and I was a dan player, too. I did not know how to handle it. Mannen kos have been more frequent, but I did not handle them right, either. In my case it was not because of a conscious decision not to study them, but because of negligence and lack of study material. Oh, I saw them being played in pro games, but without commentary, or without sufficient commentary.

In a more extreme way, pros are "guilty" of similar pragmatic decisions. For example, in the early days of Sino-Japanese games, there were cases of embarrassment because a player (e.g. Kobayashi) had not bothered to spend time on learning the other player's ruleset.

In another recent thread Bantari suggested that he preferred to play games and study them to studying problems. I am pretty much of the same school. Such an approach is pragmatic. However, in my case it has led to uneven development. If I had understood approach kos better, I expect that I would have played more of them, for instance.

[gowan]

Though these shapes are not common in pro games, it's my impression that the L+ type shapes occur often in kyu-rank players' games. In that case studying this family of shapes could be of use to these players.

[John Fairbairn]

Gee, what I heard was that mastery of the capenter's square indicated shodan strength. Evidence of rank inflation?

Deflation if anything. You didn't actually mishear, but that form of the saying came from the early 20th century when there was no distinction between pro and amateur ranks, or kyus. Top amateurs were routinely called 1-dan, i.e. nominally same as pro 1-dans.

Nowadays the saying is usually expressed as evidence of 5-dan or 6-dan strength, which is maybe deflation, as 7- or 8-dan amateur seems a better fit with beginning pro.

Before the war especially, bit even after, Kido and other magazines would run long series on the carpenter's square every two or three years, but next to nothing on other positions. They really did think it was important. How many western amateurs can truthfully say they know how to play the CS? If you can't, then is it not reasonable to suggest that spending time on mannen-ko instead is a little self-indulgent?

But I think gowan's point about kyu players is a good one.

To give an analogy, it's very practical to learn multiplication tables to get good at multiplying. You'll often have to multiply single digit numbers, such as 7x6 or 9x3. But it's also important to practice multiplying larger numbers, too. You probably won't often have to multiply 358x147, but you need to practice the process of multiplying uncommon numbers.

Not common in my world, though I can do it without a calculator if I have to. But I don't think the analogy quite fits anyway. At school I learnt how to do things like find the square root of a number using paper and pencil. That might be a better fit with learning some of the weirder positions. The point then is that I don't think I have ever had to use that now lost skill in over 50 years, even though as a technical translator I've been heavily involved in scientific work, and for quite a time I was also a reporter on the UK's most well known science magazine and wrote for engineering magazines. I didn't even cheat and use a calculator. The issue, like hanezeki, just never came up.

[Kirby]

Not common in my world, though I can do it without a calculator if I have to. But I don't think the analogy quite fits anyway. At school I learnt how to do things like find the square root of a number using paper and pencil. That might be a better fit with learning some of the weirder positions.

My perspective is that, while the position may be "weird", the process of systematically reading through a weird position is not weird - it's a valuable skill. What I was trying to get at in the analogy is that you have this set of fundamental and practical knowledge, and then you have this system for solving arbitrarily complicated problems. And getting used to this system needs practice.

So, in my opinion, that's where the value in solving "weird" position lies: you practice your ability to systematically work through something weird to come up with the correct solution.

[Cassandra]

So, in my opinion, that's where the value in solving "weird" position lies: you practice your ability to systematically work through something weird to come up with the correct solution.

To get the correct solution, you will have to do so thoroughly. In my opinion, this is the most important aspect.

Evaluating the "difficulty" of a Tsume-Go problem is not so easy; and different authors give different estimations in their books for the same problem.

In my experience, there is a large, and decisive, difference between

-- finding the (often quite obvious) vital point of a problem, and also the (sometimes quite obivous) primary solution sequence that is usually given in the books, and
-- finding the correct answer to some (might be "weird") alternative moves of either the defender, or the attacker, which usually are not included in most of the books.

There are a lot of problems that are given as (quite) "difficult", not because the primary solution sequence is so very difficult to find, but because the variation tree of the solution is so large and confusing.

[Richard Hunter]

First, thanks to emeraldemon for asking this interesting question.

This rather artificial position is one that has appeared in many go books over a long span of time. It certainly used to be considered alive. But books contain mistakes and knowledge evolves.

The position is discussed with 9 diagrams in 'roku dan gokaku no shikatsu 150 dai' 6 dan life and death 150 problems published by Nihon Kiin in 2002. After discussing the usual lines, the final diagram states that mannen ko is correct.

This book is listed in the SL page:
http://senseis.xmp.net/?NihonKiInDanLevel
Probably included in the Kisedo series 'Graded Go Problems for Dan Players', which doubled up to 300 per book, but I don't have the English books.
http://senseis.xmp.net/?GradedGoProblemsForDanPlayers