Life In 19x19

Segoe Kensaku, possibly the best player in the world at one time, was known for his propensity in any position to look first for the tesuji. As a senior administrator for the Nihon Ki-in as well, he was clearly a well organised type and was apparently not above making lists. Here is a list he made of the types of tesujis required in life and death. It is not clear why he subdivided item 24.

Problems can also be grouped into "kill" and "live" types and sub-types with the items above put into each of the appropriate sets. That portion is omitted here but will be on the next GoGoD CD.

I don't suppose the list was meant to be definitive or complete, and I'm not sure if it was ever meant to underlie his famous tesuji dictionary. The classification there is the boring "tsuke" "hane" "kosumi" type, but I suspect that may be due to an editor. The dictionary, however, does give examples. You can decide for yourself whether examples are more important than lists, or whetever, but it is at least interesting to see other minds at work, and it may be worth collecting examples of Segoe's categories here.

Segoe's classification of life & death tesuji

1. Eye-stealing tesuji
2. Throw-in and snapback tesuji
3. 2-1 point tesuji
4. The enemy's best point is my own best point
5. Shortage of liberty tesuji
6. Centre of symmetry
7. Tesuji active on two sides
8. Eye-making tesuji
9. Tesuji to broaden eye-space
10. Tesuji to reduce eye space from the outside
11. Accurate order of moves
12. Under the stones tesuji
13. Kosumi on the first line
14. Jump on the first line
15. First-line placement tesuji
16. First-line sagari tesuji
17. First-line knight's move tesuji
18. First-line narabi tesuji
19. 1-1 point tesuji
20. Tesuji using the special properties of the corner
21. Tesuji of adding one stone to make two
22. Tesuji using sacrifice stones
23. Tesuji exploiting opponent's weak points (e.g. cut)
24A. Clamp tesuji
24B. Butting attachment (tsuppari)
24C. Cut across the knight's move
24D. Wedge-in tesuji
25. Using outside surrounding stones
26. Tesuji exploiting an existing hane
27. Tesuji using indirect attack
28. Tesuji that go against common sense

Let me make a bit of actual classification of the random selective list.

First line
3. 2-1 point tesuji
13. Kosumi on the first line
14. Jump on the first line
15. First-line placement tesuji
16. First-line sagari tesuji
17. First-line knight's move tesuji
18. First-line narabi tesuji
19. 1-1 point tesuji
20. Tesuji using the special properties of the corner

Eye shape
1. Eye-stealing tesuji
2. Throw-in and snapback tesuji
8. Eye-making tesuji
9. Tesuji to broaden eye-space
10. Tesuji to reduce eye space from the outside

Shape
6. Centre of symmetry
24A. Clamp tesuji
24B. Butting attachment (tsuppari)
24C. Cut across the knight's move
24D. Wedge-in tesuji
26. Tesuji exploiting an existing hane

Sacrifice
21. Tesuji of adding one stone to make two
22. Tesuji using sacrifice stones
12. Under the stones tesuji

Misc
4. The enemy's best point is my own best point
5. Shortage of liberty tesuji
7. Tesuji active on two sides
11. Accurate order of moves
23. Tesuji exploiting opponent's weak points (e.g. cut)
25. Using outside surrounding stones
27. Tesuji using indirect attack
28. Tesuji that go against common sense

This shows that it is not a systematic classification but some topics are much more emphasised than others.

John, I gather that he numbered the list. Very modern of him.

I couldn't help but be reminded of this classification system, which no doubt would work well for tesuji:

I wonder why throw-in and snapback are mentioned in one group. To me these two seem to be two different techniques.

If both are meant to kill, then both throw-in and snapback are capturable-1 plays currently played to change unsettled opposing stones to dead. So it is possible to perceive them as one class of tesuji.