2.3.7 Territory in Seki and the Problem of One-Sided Liberties
Dias. 2-17-1 and 2-17-2 are often cited in relation to counting
territory in a seki. The points at A and B in Dia. 2-17-1 are White's
territory, and he can play on either one without loss. That much is
clear, but the Japanese rules do not count territory in a seki. Defining
seki rigorously is surprisingly difficult, and the problem of seki
presents an important, basic choice to be made in formulating the rules.
A similar problem concerns one-sided neutral points such as the numbered
points in Dias. 2-18-1, 2-18-2, and 2-18-3. Only White can occupy the
two points in Dia. 2-18-1 without loss. In Dias. 2-18-2 and 2-18-3 the
question is whether the false eyes should be considered territory or
one-sided neutral points that only one player can occupy. In area rules
these points all count toward the score of the player who occupies them.
The issue of whether to count territory in a seki or to count one-sided
neutral points should be noted as a key issue in the rules. It separates
those who want to define life, death, and seki from those who want to
write the rules without these definitions. In writing rules that count
territory and prisoners, this is the most important issue.