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The positions with commentaries

                                         

   

   

   

                                         

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Bestiary


(work in progress)

 

 

Introduction
I. Extraordinary life and death problems.

    

1. Symmetrical problems
2. Snapbacks (uttegaeshi)
3. Under the stones (ishinoshita)
4. Eye reduction (nakade)
5. Blind spots
6. Reference positions
7. Most difficult classical problems
II. Paradoxical tesujis and strange manoeuvres.

    

1. First line moves
2. Shortage of liberties (damezumari)
3. Off-limits moves and phantom go
4. Impossible cuts (atekomi, warikomi, etc.)
5. Traps and variations of joseki
6. Extraordinary moves played in real games
III. Ladders and other incredible sequences.
IV. Semeais, sekis and pseudo-sekis.
V. Problems about rules.

Introduction

Here, you will only find my bestiary of interesting positions and problems (162 of them) ; go there for motivations, solutions and detailed commentaries.

While most of those problems are "artistic" ones, many of them are quite hard, so I thought useful to give a (very rough) indication of their difficulty : some easy reference positions are not ranked, but for the others :
one means the problem can be solved (in a reasonable time, without moving stones) by a player around 1k (52 problems),
two means a 5d level (57 problems),
three means a professional level (40 problems).
And, of course, Dosetsu's problem, and 12 others, are ranked ...

phase 3

Appetizer : Black to play ; status ?
Solution and commentaries

I. Extraordinary life and death problems.

1. Symmetrical problems

problème 4

Problem 1 : Black escapes        
Solution and commentaries

         problème 5

Problem 2 : the mask, most difficult symmetrical problem
(Black to play and save his five surrounded stones)  
Solution and commentaries


problème 6

Problem 3 : Black to play and kill
Solution and commentaries

problème 6

Problem 4 : Black to play and kill
Solution and commentaries

problème 7

Problem 5 : Black to play and escape  
Solution and commentaries

 

problème 8

Problem 6 : What is best yose play for Black ?
Solution and commentaries



2. Snapbacks (utegaeshi)

problème9

Problem 1 : Black to play and kill
Solution and commentaries

problème9

Problem 2 : Black to play and kill
Solution and commentaries

problème9

Problem 3 : Black to play and kill
Solution and commentaries

                    problème9

Problem 4 : Black to play and live  
Solution and commentaries

problème9

Problem 5 : White to play and live
Solution and commentaries

problème 10

Problem 6 : Black to play and live
Solution and commentaries

               problème 11

Problem 7 : Black to play and live   
Solution et commentaires

   problème 11

Problem 8 : Black to play ; status ?  
Solution and commentaries



  problème 12

Problem 9 : Black to play and save the marked stones
Solution and commentaries

3. Under the stones (ishinoshita)

exemple a

Example 1 : Black to play and live 
Solution and commentaries

exemple b

Example 2 : Black to play and live   
Solution and commentaries

exemple c

Example 3 : Black to play and kill
Solution and commentaries


exemple a

Problème 4 : Black to play and live 
Solution and commentaries

exemple b

Problème 5 : Black
to play and kill  
Solution and commentaries

             exemple a

Position 6 (a natural one) : what is White's best yose (and how much is it worth)?
Solution and commentaries

exemple a

Problem 7 : Black to play and kill by ko 
Solution and commentaries

       exemple b

Problem 8 : Black to play and live unconditionally   
Solution and commentaries

       exemple c

Problème 9 : White to play and live
Solution and commentaries

exemple thématique

Problem 10 (highly artificial) : Black to play ; status ?
Solution and commentaries  

   exemple thématique
Problem 11 (from a real game ?) : how could White afford to ignore the ko threat ?
Solution and commentaries


exemple thématique

Example 12 : Black to play and live 
Solution and commentaries

un piège pour pros
Problem 13 : Black to play ; status ?
Solution and commentaries



4. Eye reduction (nakade)

problème 17

Problem 1 : Black to play, status ?
Solution and commentaries

     problème 17

Problem 2 : Black to play, status ?
Solution and commentaries

problème 17

Problem 3 : Black to play, status ?
Solution and commentaries

         problème 17

Problem 4 : Black to play and kill (without ko).
Solution and commentaries

problème 17

Problem 5 : White to play, status?   
Solution and commentaries

problème 17

Problem 6 : Black to play and live.
Solution and commentaries

problème 17

Problem 7 (variation) : White to play and kill.
Solution and commentaries


problème 17

Problem 8 : Black to play and kill (without ko).
Solution and commentaries

problème 17

Problem 9 : Black to play and kill.
Solution and commentaries

   problème 18

Problem 10 : Black to play and kill.
Solution and commentaries

  
problème 18

Problem 11 : Black to play and kill.
Solution and commentaries



problème 18

Problem 12 : Black to play and kill.
Solution and commentaries

avant la capture   

Problem 12a : Black to play and kill every white stone.
Solution and commentaries

avant la capture

Problem 12b : Black to play and kill every white stone.
Solution and commentaries

l'appât avale le poisson

Problem 13 : White to play and kill every black stone.
Solution and commentaries

l'appât avale le poisson

Problem 14 : White to play and kill every black stone.
Solution and commentaries

       


5. Blind spots

un autre piège pour pros

(?) Problem 1 : White to play ; status ?
Solution and commentaries  

un autre piège pour pros

(?) Problem 2 (variant) : Black to play ; status ?
Solution and commentaries  

un autre piège pour pros

(?) Problem 3 : Black to play ; status ?  
Solution and commentaries



6. Reference positions

problème de Saijo

Problem 1 : Black to play and kill without ko         
Solution and commentaries


solution 3

Problème 2 : Black to play ; status ?      
Solution and commentaries


solution  1

Problem 3 : Black to play and kill         
Solution and commentaries

solution 2

Problem 4 : Black to play and kill         
Solution and commentaries

solution 3

Problem 5 : Black to play ; status ?
Solution and commentaries

solution 3

Problem 6 : Black to play and kill the white stone
Solution and commentaries


7. Most difficult classical problems



problème 1

Problem 1 (empress of tsumego) :        
White to play and kill by ko
Solution and commentaries

problème 1 bis

Variant : the Japanese setting
Solution and commentaries


problème 2

Problem 2 (emperor of tsumego) :
no other stones on the board ; White to play and kill.
Solution and commentaries

        problème 1 bis

An improved variant ?
Solution and commentaries

         problème 1 bis

The ultimate variant (?) : no other stones on the board ; Black to play and live
Solution and commentaries


problème 2 bis

Problem 3 (a serious contender) : White to play; status?         
Solution and commentaries

le plus difficile

Problem 4 (Dosetsu's problem, the most difficult ever) :
Black to play and win the game   
Solution and commentaries

 

II. Paradoxical tesujis and strange manoeuvres.

1. First line moves

problème 1

Figure 1 : Black played the monkey jump ; how to block, and how many points does Black score ?
Solution and commentaries

  problème 1

Problem 2 : Black to play ; what is the best yose ?
Solution and commentaries

  problème 1

Problem 3 : Black to play and kill
Solution and commentaries

  problème 1

Problem 4 : Black to play ; status ?
Solution and commentaries

problème 1

Problem 5 : Black to play and save the marked stones
Solution and commentaries


problème 1

Problem 6 : Black to play and save his surrounded stones
Solution and commentaries


problème 2

Problem 7 : Black to play and capture the 4 white stones
Solution and commentaries


Problem 8 : Black to play and live
Solution and commentaries

Problem 9 : White to play and kill the NE group
Solution and commentaries


2. Shortage of liberties (damezumari)

figure 1

Figure 1 : Black to play and kill    
Solution and commentaries

figure 1

Figure 2 : Black to play and kill     
Solution and commentaries

         un problème rafraîchissant

         Problem 3 :
         Black to play and capture the three corner stones
Solution and commentaries

figure 1

Figure 4 : Black to play and save the corner stones     
Solution and commentaries

         un problème rafraîchissant

    Figure 5 : Black to play and live
Solution and commentaries

figure 1

Problem 6 : Black to play and live    
Solution and commentaries

         un problème rafraîchissant

    Problem 7 : Black to play and live
Solution and commentaries

         un problème rafraîchissant

   Problem 8 : Black to play and live
Solution and commentaries


figure 1

Position 9 (a classical one) : Black to play and live (without ko)     
Solution and commentaries

         un problème rafraîchissant

         Problem 10 : Black to play and live
Solution and commentaries

         un problème rafraîchissant

   Problem 11 : Black to play and live
Solution and commentaries

         un problème rafraîchissant

Example 12 : Black to play and live
Solution and commentaries

         un problème rafraîchissant

Problem 13 : Black to play and live (or escape)
Solution and commentaries

         un problème rafraîchissant

Problem 14 : Black to play and live (what is the use of the marked stone ?)
Solution and commentaries

3. Off-limits moves and phantom go

figure 1

Figure 1 : Black to play and cut     
Solution and commentaries

        

Problem 2 : Black to play and escape efficiently
Solution and commentaries

         figure 1

Figure 3 : How to punish the cut ?     
Solution and commentaries

figure 1

Figure 4 : Black to play and connect the marked stones
Solution and commentaries

     figure 1

Figure 5 : White to play and capture the side
Solution and commentaries

              figure 1

Problem 6 : after the figure 5 attack, how can Black escape ?
Solution and commentaries     


figure 1

Problem 7 : Black to play, status ?
Solution and commentaries

     figure 1

Problem 8 : Black to play and capture the marked stones
Solution and commentaries

figure 1

Problem 9 : Black to play and save the 6 stones on the side
Solution and commentaries

figure 1

Problem 10 : Black to play and live
Solution and commentaries

     figure 1

Problem 11 : Black to play ; status ?
Solution and commentaries



4. Impossible cuts (atekomi, warikomi, etc.)


        Problem 1 :
        Black to play and save his surrounded stones.
Solution and commentaries

         Problem 2 :
        Black to play and cut part of the white group.
Solution and commentaries
figure 1

Problem 3 : Black to play and save the marked stones.     
Solution and commentaries




         Problem 4 : Black to play and live or escape.
Solution and commentaries

figure 1

Problem 5 : Black to play and capture the largest white string     
Solution and commentaries

figure 1

Problem 6 : Black to play and live.  
Solution and commentaries

figure 1

Figure 7 : Black to play and exploit white weaknesses.     
Solution and commentaries

figure 1

Problem 8 : Black to play and live (and what happens then to the white group ?).
Solution and commentaries

figure 1

Problem 9 : Black to play and save the marked stones.    
Solution and commentaries

5. Traps and variations of joseki

solution 1

Position 1 : White to play. If he blocks (left of 15), he will capture the cutting stones. So what is Black's plan ?   
Solution and commentaries

figure 1

Position 2 : Black 5 looks suspicious ; what must White do, and where is the trap ?     
Solution and commentaries

6. Extraordinary moves played in real games

figure 1

Position 1 : how would White put an immediate end to this game ?    
Solution and commentaries


piège

Position 2 : what is the threat behind this move ? And how should Black answer ?     
Solution and commentaries


figure 1
Position 3 : Black to play and wake up the corner aji
Solution and commentaries


figure 1
Position 4 : Black to play ; status?
Solution and commentaries


figure 1

Position 5 (first moves of the most famous game in history) :
what happens if Black plays the "natural" ko threat above 31?     
Solution and commentaries


figure 2

Position 6 (later in the game) : now, what was Black answer to White attack at 126 ?    
Solution and commentaries

III. Ladders and other incredible sequences.



piège

Problem 1 : Black to play and put the marked stones to best use
Solution and commentaries   

        piège

Problem 2 : Black to play and awaken the aji of the marked stone
Solution and commentaries   

        piège

Problem 3 : Black to play and force White (O Meien) to resign    
Solution and commentaries

piège

Problem 4 : White to play and live with the SE group    
Solution and commentaries

piège

Problem 5 : Black to play and capture the marked stones    
Solution and commentaries

piège

Problem 6 : Black to play and make
both groups on the south edge live
Solution and commentaries

         piège

Problem 7 : Black to play and make both groups in NE and SW corners live    
Solution and commentaries


 

piège

Problem 8 : White to play and capture the marked stones   
Solution and commentaries

 

piège

Problem 9 : White to play and save the marked stones    
Solution and commentaries

 

piège

(?) Problem 10 : White to play ; what happens if he tries to save the south edge group ?    
Solution and commentaries

piège

Problem 11 : White to play ; what is the result ?    
Solution and commentaries



IV. Semeais, sekis and pseudo-sekis

Figure 1
Figure 1 : who wins the semai? 
Solution and commentaries

Figure 2 
Figure 2 : White to play ; who wins the semai?
Solution and commentaries

Figure 2
Figure 3 : what is the result of the fight ?
Solution and commentaries

Figure 2
Figure 3bis : what is the result of the fight ?
Solution and commentaries

Figure 3

Figure 4 : what is the result of the fight ?
Solution and commentaries

Figure 2 
Semeai 5 : Black to play and win the race
Solution and commentaries

Figure 4
Semeai 6 : Black to play and
win the game
Solutions and commentaries

Figure 5
Semeai 7 : what is the winning strategy
in this case?

Figure 4
Figure 8 : a well-known seki, but how is it scored ?
Solution and commentaries

Figure 5

Figure 9 : what say the rules ?
Solution and commentaries

Figure 6

Figure 10 : what is the result ?
Solution and commentaries

Figure 6 bis

Figure 11 : what is the difference with the previous position ?
Solution and commentaries

Figure 6

Figure 12 : and what is the result in this case ?
Solution and commentaries

Figure 7

Figure 13 : an asymmetrical seki
Solution and commentaries

Figure 8-1 Figure 8-2
Figure 8-3


Figure 14 : what is the strange relation between those three positions?
Solution and commentaries

Figure 9-1 Figure 9-2 Figure 9-3


Figure 15 : sekis or false sekis ?
Solution and commentaries

figure 10

Figure 16 : what is the result ?
Solution and commentaries

Figure 1 (W 0 -- W 0)

Figure 17 : what say the rules?
Solution and commentaries

Figure 11

Figure 18 : what say the rules?   
Solution and commentaries

Figure 11 bis

Figure 19 : how must the fight be played ?
Solution and commentaries

Figure 12
Figure 20 : what is the result of the fight ?
Solution and commentaries
Figure 12a
Figure 21 : what is the difference with the previous one ?
Solution and commentaries
Figure 12a
Figure 22 : is this really a complete seki ?
Solution and commentaries
         Figure 13
(?) Figure 23 : Circular hanezeki ; what happens ?
Solution and commentaries

 

V. Problems about rules.

 

 
Reference figure 1: "bent four in the corner" ;
why is Black dead ?
Solution and commentaries

  


Figure 2 :  bent four, with an
unremovable ko threat ; what say the rules ?
Solution and commentaries

  

 
Figure 3 : "generalized" bent four ;
what say the rules ?
Solution and commentaries

 
Figure 4 : How many points for Black ?
Solution and commentaries

Figure 5 : are the 4 white stones in the corner really dead ?
Solution and commentaries



The following positions illustrate relatively common superko situations (see here for solutions and commentaries)

Exemple 6 : semeai with triple ko

       

Exemple 7 : simple ko with active seki

       

Exemple 8 : "round robin ko"

       

Exemple 9 : phoenix (chosei)   



Figure 10 : is the NW group really alive in seki ?
Solution and commentaries

Figure 11 : Black to play ; how will the game continue ?
Solution and commentaries


Position 12 : self-captures allowed ; what does this change ?
Solution and commentaries

Curiosity 13 : It's White turn. Black retracts her last move, then lives
Solution and commentaries

       

Curiosity 14 : Black to play and die
Solution and commentaries

       

Variant 15 : self-capture allowed ; Black to play and live
Solution and commentaries

(?) Curiosity 16 : White to play and save the black stones in the SW corner (and who wins the game then ?)
Solution and commentaries

Curiosity 17 ("unfair go") : White is allowed to play twice after every black move. Who wins the game ?
Solution and commentaries