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Conventions in Life and Death
    Keywords: Life & Death

The assumptions in life-and-death (tsumego) problems are rarely spelled out.

They include:

  • board otherwise empty;
  • escape from the local position is good enough for life;
  • no effects from corners of the board not represented in the diagram;
  • seki is obviously a solution to a life problem.

On the other hand it is assumed that

  • ko is a solution;
  • there are worthwhile non-local ko threats.

There is usually no call to read ladders, but logically speaking we should assume all ladders are good. Note that being chased in a ladder doesn't count as escape.

To be quite precise is a little tricky. Something like this: we assume an otherwise empty board that is semi-infinite in any direction with an unmarked corner, but is a large band (to make ladders work); and we add in a second board as direct summand for ko threats to inhabit.

As far as the solution goes: in Japanese books it is considered enough to establish the status. That means life, death or ko. Matters to do with endgame plays and leaving ko threats, for example, aren't covered. I think that a solution would be preferred if it gave first capture in a ko to the attacker for a 'to kill' problem (resp. to the defender in a 'to live' problem) (see try to get first capture in a ko). Probably matters such as number of ko threats go beyond the normal specification of tsumego, however important they might be in a real game.

Here on this site you can find discussion of those extra matters in some particular cases.

On the J-groups page you can find some more talk about conventions: for example the explicit placement of stones as barriers to escape.

Charles Matthews


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This is a copy of the living page "Conventions in Life and Death" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.