It is currently Fri Apr 19, 2024 3:03 pm

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 10 posts ] 
Author Message
Offline
 Post subject: The most difficult problem ever / Igo Hatsuyoron 120
Post #1 Posted: Sat Dec 03, 2011 10:09 am 
Judan

Posts: 6145
Liked others: 0
Was liked: 788
Review: The most difficult problem ever / Igo Hatsuyoron 120

Title: The most difficult problem ever / Igo Hatsuyoron 120
Author: Thomas Redecker
Publisher: Brett und Stein Verlag
Edition: 2011
Language: German + English
Price: EUR 15
Contents: tsumego
ISBN: 978-3-940563-18-7
Printing: good (very good in relation to layout + paper)
Binding: rather weak
Layout: good (but small diagrams + bilingual)
Editing: good
Translation: good
Publisher's Choice: doubtful (too few pages to reduce price)
Pages: 140
Size: 168mm x 220mm
Diagrams per Page on Average: 3
Method of Teaching: (mostly) examples
Read when EGF: 7k-7d
Subjective Rank Improvement: -
Subjective Topic Coverage: -- (tsumego in general) or + (the specific problem)
Subjective Aims' Achievement: ++

Probably Igo Hatsuyoron is the most difficult classical problem collection, was compiled by Dosetsu, started as secret study material for a few first class players and is said to have been written in 1713. The whole board problem 120, which is the book's only topic, was rediscovered by Araki Naomi to be published in 1982 by Fujisawa Hideyuki (Shuko) 9p. This problem is the by far most difficult classical tsumego problem but the book title overlooks more difficult non-tsumego problems. The problem is so difficult though that some thousands of manhours of research have not proven a solution yet. The book presents a new solution but problem solving consists of another, here still missing step: the verification beyond doubt (when the book says "professionally confirmed", then that is also insufficient). Thousands of already studied variations are necessary but insufficient; there needs to be complete logical linking between all of them on a level above trivially immaterial variations. This, however, is not easy because #120 requires interesting subtrees starting from counter-intuitive, partly bad shape plays. On the other hand, the book's solution seems to be the currently by far best understanding of the problem.

Maybe the problem remained hidden for centuries because editors suspected a mistake in the problem position and could not discover its central topic. Modern study of the problem started with 1,000 manhours by Fujisawa and his study group to reveal that topic: a hane-seki with a 20 stones tail in the board's center. To 1988, Cheng Xiaoliu 6p worked on the endgame and later continued partial studies. In 2005 Joachim Meinhardt 5k, in 2007 Yamada Shinji 5p, in 2007 Thomas Redecker 1k, in 2009 Harry Fearnley 2d and during the years to 2011 mainly the study group of the three mentioned amateurs found new plays, researched their consequences and developed the book's solution with occasional professional hints. Professionals started but amateurs, who have now invested some thousands of manhours, have taken the lead in the race towards a final solution.

While Redecker's manuscript Igo Hatsuyoron Problem 120 / The most difficult problem ever of 2009 had no binding, weak layout, worse language and hard to follow contents, the reviewed book makes great efforts in teaching the problem's structure, timing of moves, global relation of local status and decisions, history of the problem's research and a few fundamentals of approach liberties, regular and circular hane-sekis. While the first half of the book has sufficiently many variations, the second half's study of recent discoveries shows too few representative variations and points to webpages. Despite this unfortunate restriction by the publisher, the reader can follow what this problem is all about and where current research resides. Nevertheless, I expect having to read the book thrice to really understand all the contents, each play and its correct timing in each variation and the long term impact of some plays with peculiar timing. Whoever would want to join the study group must also read over 1,000 variants on webpages and ask for any most recent variants. The ordinary reader will be happy to get at least a good overview on the problem from the book.

So what happens in the problem? Imagine four difficult problems, one in each quarter of the board. Each is about tsumego, life and death and endgame and each has its spectacular aspects. For example, the hane-seki is not ordinary but has two additional groups and many global side effects for cutting problems, life and death and endgame in the other parts of the board. The exact position of each stone on the board matters and the interdependence of shapes and variants creates an extraordinarily complex whole board Black to play and possibly win problem. The various parts and aspects are so well integrated to each other that it is hard to believe in coincidence. Dosetsu's knowledge must at least have anticipated today's partial solution knowledge. Presumably he spent years on creating the problem. This makes it an artful masterpiece and celebration of the human mind. We play Go because we admire such great depth and skill.

Of course, nobody needs a book on just one problem and being not particularly suitable for rank improvement. One can also criticise one or another detail like a missing note in the legend whether captured stones count at the beginning or end of a diagram's variation. Such misses the point. The book, and especially for its price, is one of the first choices among the appreciation type of Go literature and furthermore evidence of the growing power of Western amateur research.


This post by RobertJasiek was liked by 4 people: cyclops, daal, ez4u, Joaz Banbeck
Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #2 Posted: Sun Dec 04, 2011 12:52 am 
Beginner

Posts: 9
Location: Kenya
Liked others: 2
Was liked: 0
Rank: KGS 11 kyu
KGS: mafidufa
I think the most difficult problem ever is this

Click Here To Show Diagram Code
[go]$$c White to win.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:)

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #3 Posted: Sun Dec 04, 2011 3:54 am 
Judan

Posts: 6145
Liked others: 0
Was liked: 788
The empty board, White to win, no komi was solved several times incl. a much more general CGT solution by John Conway: White can at best tie.

Apart from such old jokes
https://groups.google.com/group/rec.gam ... ode=source
https://groups.google.com/group/rec.gam ... ode=source
https://groups.google.com/group/rec.gam ... ode=source
the most difficult go research problems, each with over 10,000 manhours for me, include a) explanation of the Japanese 1989 Rules and b) definition of ko in general. That's why my review speaks of the most difficult "classical tsumego" problem.


This post by RobertJasiek was liked by: ez4u
Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #4 Posted: Sun Dec 04, 2011 3:34 pm 
Gosei
User avatar

Posts: 2011
Location: Groningen, NL
Liked others: 202
Was liked: 1087
Rank: Dutch 4D
GD Posts: 645
Universal go server handle: herminator
RobertJasiek wrote:
the most difficult go research problems, each with over 10,000 manhours for me, include a) explanation of the Japanese 1989 Rules and b) definition of ko in general. That's why my review speaks of the most difficult "classical tsumego" problem.


If Igo Hatsuyoron 120 had thousands of hours invested in it, including many by professionals, and is there is still no definitive solution, how can you conclude that it is less difficult than the two rules related problems you mention?

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #5 Posted: Sun Dec 04, 2011 4:32 pm 
Judan

Posts: 6145
Liked others: 0
Was liked: 788
1) I do not see the "many" professionals. Some, ok.

2) Most of the time has been invested by 5k - 2d players. They need much longer for finding moves than I would (in rules studies, I see necessary counter-intuitive moves even if they are passes or fill the third eye; I guess I would have found the double guzumi within weeks instead of years because it is an easier move type, serves clear purposes of threatening eyeshape and creating approach defects and fighting in the semeai, I had developed the concept of threatened eye as an alternative to immediate eye in 1998, i.e. before knowing the problem) and they need much longer for finding and checking variations that I would. So the some thousands of their invested manhours translate to maybe 2,500 I would have invested.

3) From seeing the current book, I get a rough idea of how much remaining work needs to be done. My guess is: another 5d mathematically skilled rules expert's 2,500 manhours but not more.

4) That different people with communication problems have worked at different places means that time must have been wasted for doubled work or void attempts. A single person working alone would have the advantage of efficient work, once the initial 1,000 manhours were invested.

So altogether #120 I estimate as a problem requiring (me, if I were the person to have attacked the problem after the first 1,000 hours) altogether less than rather than more than 10,000 manhours.

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #6 Posted: Mon Dec 05, 2011 3:56 am 
Gosei
User avatar

Posts: 2011
Location: Groningen, NL
Liked others: 202
Was liked: 1087
Rank: Dutch 4D
GD Posts: 645
Universal go server handle: herminator
RobertJasiek wrote:
1) I do not see the "many" professionals. Some, ok.


I did not claim many professionals, just many hours by professionals.

Quote:
I guess...

...I get a rough idea... My guess...

...I estimate...


Unless you "know" these things, it is premature to make claims on the relative difficulty of these problems. Prove instead of guess.

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #7 Posted: Mon Dec 05, 2011 5:02 am 
Judan

Posts: 6145
Liked others: 0
Was liked: 788
HermanHiddema wrote:
just many hours by professionals.


We have
- the 1,000 h by Fujisawa's study group;
- two editions of Hatsuyoron by Cheng but with apparently much less effort than the amateur study group, so maybe we can assume 1,000 h by him on only the particular problem;
- some thousands (according to Redecker a 4-digit number) of manhours by the amateur study group, which means at least 1,000 and less than 10,000, which means in view of the kind of variations they have found about 2,500 h I would have needed for their work;
- several dozens or maybe a few hundred of hours of professional assistance for a few of the amateur study groups' particular endgame questions;
- yes, the last two items are only a guess, but it is a very reasonable guess because a) Local Move Selection is something I use regularly in my games, so all the new moves I would have discovered quickly instead of needing years, b) I have always used a "consider all possible plays" approach in tsumego problems (this is a disadvantage for improvement because it slows down reading but it is an advantage for problems with "spectacular" moves; e.g., B and C on p. 91 I would of course consider because these are 1-connections), c) I have always loved bad shape tesujis.

Quote:
Unless you "know" these things, it is premature to make claims on the relative difficulty of these problems. Prove instead of guess.


I would prefer to prove instead of guessing, too. There are many problems I find more interesting though, so probably I can't prove before others do. Making an educated guess is better though than leaving the book title's claim uncommented!

As far "proving" of the manhours I needed for the rules problems is concerned, here are two hints: 1) For developing the New Ko Rules, I needed 1,100 h. 2) After 10 years of preliminary studies, the final and full-time work of J2003 creation was 11 months at ca. an average of 15h / day (not counting insights gained during dreams), which are already ca. 5019 h.

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #8 Posted: Mon Dec 05, 2011 7:37 am 
Lives in sente
User avatar

Posts: 1310
Liked others: 14
Was liked: 153
Rank: German 1 Kyu
RobertJasiek wrote:
2) Most of the time has been invested by 5k - 2d players. They need much longer for finding moves

Especially with this problem, the usage of TIME makes up for a difference in playing strength.

One example: We needed -- it's long ago, so let's say -- about two months to find a refutation of one of White's strongest alternatives in the top left corner after Black's Guzumi in the top right. Then I had the opportunity to ask Yoon Young-Sun 8p in person about this situation. After a -- may be -- 30 seconds look on the board, she showed me "Black here - White here - Black here", the same sequence in three quick shots that we found after some months' work.

However, there is the danger that stronger players -- especially professionals -- badly underestimate the quality of the results of some amateur Kyu players. Just because they do see only their minor playing strength, but not the large amount of time invested. And do not realize that even amateurs -- on a very small field -- can work with a professional attitude.

In addition, there may be the effect that some of our amateurish Kyu sequences do look very "faulty" or at least "ugly" in higher Dan players' of professionals' eyes, especially when the endgame is concerned. And this may result in an estimation of a low quality overall.

But one has to be aware that -- in my opinion -- this problem is very friendly to amateurs, because it forgives amateurs (but not professionals !) for their mistakes. For example, an endgame sequence of ours may not be correct in absolute terms. We made some one-point-error for Black here, some one-point-error for White there, so our mistakes compensated for each other and our final result was (hopefully) the same as with the correct professional endgame order of moves.

I'd like to suppose that Dosetsu's genius not only was well aware of professionals' strengths and weaknesses, but in addition was also able to put himself in the position of "poor" weak players, and to be "fair" in relationship to their minor skills.


Quote:
than I would (in rules studies, I see necessary counter-intuitive moves even if they are passes or fill the third eye; I guess I would have found the double guzumi within weeks instead of years because it is an easier move type, serves clear purposes of threatening eyeshape and creating approach defects and fighting in the semeai, I had developed the concept of threatened eye as an alternative to immediate eye in 1998, i.e. before knowing the problem) and they need much longer for finding and checking variations that I would. So the some thousands of their invested manhours translate to maybe 2,500 I would have invested.

Revealing the Guzumi itself was the work of "only" one month's search, not of "years", but finally getting to know about the correct moment, when to play it, took several more months. During this period, Joachim had a lot of work to do to get rid of all the mistakes in my previous ideas and to refute them. But the task itself was relative "simple": "Find a place on the board, where Black can destroy some points of White's territory successfully." This is not at all comparable to the initial professionals' burden of "Try to solve the problem." Probably I was badly handicapped over a long period of time, because I looked for a possibility to further reduce White's territory in Sente only. But the Guzumi is only Gote locally.

Surely, a much stronger player -- given the task mentioned above -- would have found the Guzumi faster. But there was none available ;-)

Kang Kyoung-Nang 7d told us recently that the Guzumi would be "naturally" considered by professionals, because it was a "typical" endgame move. Well, why Fujisawa didn't use it in 1982 ? The answer may be quite simple: There was no need to do so. Fujisawa's solution sequence ended in a victory for Black, so it was not necessary to widen the score by using some doubtful bad-shape-move.

Similarly, you will find no hint in the known sources that the main task of the problem cannot be providing Black's big top right group with two eyes. Black would be able to do so within the first 20 moves -- there is no way for White to prevent this -- but thereafter, White won the game by at least five points. Please pay attention that you will not find anything about this fact in the book, we discovered it after printing.

Harry once guessed that -- in principle -- the Guzumi could not be correct, because of the very wild bunch of possible variations in the top left corner thereafter. He mentioned that it is absolutely unusual for a classical problem to establish a lot of pressure to refute this very large amount of possible sequences for confirming the Guzumi as being correct. Possibly Dosetsu considered this a suitable way to "hide" the solution, who knows ?


Quote:
4) That different people with communication problems have worked at different places means that time must have been wasted for doubled work or void attempts. A single person working alone would have the advantage of efficient work, once the initial 1,000 manhours were invested.

I don’t think that you are correct with these statements.

We three amateurs have our special strengths and weaknesses -- in general or concerning the work on this problem only -- resulting in the effect that our team is much stronger -- in relation to #120 -- than the average of our ranks.

So nearly no time has been wasted for doubled work. But you are right that there have been many void attempts, done by one team-member, refuted by another one. However, the latter is due to our low ranks, and cannot be avoided. And, on the other hand, there have been many ideas, only mentioned by one team-member, worked out in detail by another one. These are the highlights of teamwork.

The "single person" you mentioned above must have a much higher rank than ours to provide the "efficient work" really efficiently. It might be preferable to have at least "two persons", due to the imminent danger of individual blind spots.

But by now, there is no longer the must to invest 1,000 hours in the very beginning. Our book gives a thorough analysis of the problem, and understanding of its pre-conditioned contents -- to get the ability to work on -- must be possible in much less time for a high-class player.

However -- you are right in your review -- the book does not help much in getting stronger, if ever. In principle, it is "only" a thorough analysis of one middle-game position. In addition, no professional can make a living from really solving #120. This is why it is so very difficult to create interest in this topic.


Quote:
3) From seeing the current book, I get a rough idea of how much remaining work needs to be done. My guess is: another 5d mathematically skilled rules expert's 2,500 manhours but not more.

...

So altogether #120 I estimate as a problem requiring (me, if I were the person to have attacked the problem after the first 1,000 hours) altogether less than rather than more than 10,000 manhours.

Of course, you would be a great assistance, but don't mess around with this problem. You have other -- by far more important -- tasks to accomplish ;-)

In my understanding, the only "big" topic remaining is the validation of the large variation tree of the "Tenuki-plays" after the Guzumi. This is answering the question, whether there is absolutely NO variation for White to refute the Guzumi. A concentration on the "critical" paths (maybe 40) seems to be appropriate and sufficient; there is no need to go over all of the (partially outdated) 1,000 variations. This task is the more time-consuming the lower the rank of the worker is, because the position of the top left corner (and the left side) is so very "open". And there are so many possibilities to go wrong.

As usual -- this is true with #120, too -- it is by far simpler to find an error in an existing sequence (for example Joachim's very decisive (re-) discovery of the "late" Oki in the lower right) than to develop a correct one on your own. This fact was one of our motives to publish the book -- make it possible for others to reveal our mistakes and to improve our solution.

_________________
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #9 Posted: Mon Dec 05, 2011 8:08 am 
Judan

Posts: 6145
Liked others: 0
Was liked: 788
Cassandra wrote:
this problem is very friendly to amateurs, because it forgives amateurs (but not professionals !) for their mistakes.


I do not care about this perception - what matters is whether something can logically be proven.

Quote:
I'd like to suppose that Dosetsu's genius not only was well aware of professionals' strengths and weaknesses, but in addition was also able to put himself in the position of "poor" weak players, and to be "fair" in relationship to their minor skills.


I am not convinced of this theory. There can be other reasons for 2 points score shifts.

Quote:
Revealing the Guzumi itself was the work of "only" one month's search, not of "years", but finally getting to know about the correct moment, when to play it, took several more months.


Thanks for the clarification.

Quote:
Harry once guessed that -- in principle -- the Guzumi could not be correct, because of the very wild bunch of possible variations in the top left corner thereafter. He mentioned that it is absolutely unusual for a classical problem to establish a lot of pressure to refute this very large amount of possible sequences for confirming the Guzumi as being correct. Possibly Dosetsu considered this a suitable way to "hide" the solution, who knows ?


The top left is the seemingly easiest local part of the board - at first glance it looks like only local endgame. So my guess is that Dosetsu created extra variation burden exactly there on purpose.

Quote:
our team is much stronger -- in relation to #120 -- than the average of our ranks.


Of course.

Quote:
So nearly no time has been wasted for doubled work.


Not within your amateur study group. What I have meant is between the different parts of the world.

Quote:
The "single person" you mentioned above must have a much higher rank than ours


Do you still underestimate the slope of strength improvement in the 3d - 7d range? :)

Quote:
the only "big" topic remaining is the validation of the large variation tree of the "Tenuki-plays" after the Guzumi.


Afterwards comes the real fun of logical verification of completeness and correctness of made assumptions, timings and move choices.

Quote:
make it possible for others to reveal our mistakes and to improve our solution.


Let me state it once more: You will have to make formal proofs instead of "professional verifications". This is not your usual problem where the solution once seen is then "obvious". All claims need to be proven.

Top
 Profile  
 
Offline
 Post subject: Re: The most difficult problem ever / Igo Hatsuyoron 120
Post #10 Posted: Mon Dec 05, 2011 9:40 am 
Lives in sente
User avatar

Posts: 1310
Liked others: 14
Was liked: 153
Rank: German 1 Kyu
RobertJasiek wrote:
Quote:
The "single person" you mentioned above must have a much higher rank than ours

Do you still underestimate the slope of strength improvement in the 3d - 7d range? :)

3d - 7d is "much higher than" 2k, the average of our teams' ranks.
Additionally, this "single person" should be very fond of Tsume-Go, preferably having it as a kind of hobby.

But remember: Even high level professionals (Fujisawa Hideyuki 9p, Cheng Xiaoliu 6p) made (sometimes easy to recognize) mistakes. So four eyes will be better than only two ;-)

_________________
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group