Seki unambiguous definition/discussion

Proposal for seki

Definition:

  1. A mutual liberty is an empty point that reaches two chains of different color.
  2. Two chains of different color live in simple seki if they reach no empty points but the same two mutual liberties.

Addition:

  1. A group of stones is alive in simple seki, if for any sequence of moves by the opponent, there is a sequence of answers that turns the group into a chain which is part of a pair of chains, complying with definition 2.
[Diagram]

Seki

(TapaniRaiko: The proposal is not enough, as these two examples show. I have seen an example where a 35x35 board was filled with small groups all living in a single seki.)

[Diagram]

Not a seki


How about something along the lines of:

"A local position with at least one mutual liberty or single point ko which cannot be filled by either side without incurring a loss." We still have to read out the consequences of moves, but I think this captures what we mean by Seki and applies to all the examples there.

jvt: This is still ambiguous: how to define which chains belong to the 'local position'? Some chains may be in seki even if they are not adjacent to any dame.


RobertJasiek: Needless to say, the Japanese 2003 Rules will provide an unequivocal definition of "seki" under those rules. For other rules, minor modifications would be necessary then.


KjeldPetersen: If a group (with max 1 eye) is moving out (not filling the eye) and thereby get into a position of atari, then this group is posible part of a seki? Look at the example at the top. All three groups will go into atari if they move out.


This is a copy of the living page "Seki unambiguous definition/discussion" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.
[Welcome to Sensei's Library!]
StartingPoints
ReferenceSection
About