Identifying the weakest framework stone - principles

The formal definition of "the weakest framework stone" is that framework stone that is easiest for the opponent to isolate. This begs the question as to what the factors are that lead to potential isolation. And having identified the factors, a more difficult question arises as to how to combine the factors in order to make comparisons. Luckily the practice is simpler than the theory, because at any one stage of the game, normally the difference between candidate stones is uncomplicated.

At the beginning of the game most framework links tend to be notional which means that the distinguishing factor is most often the number of ways a framework stone might connect - obviously the more options, the stronger the stone.

As the game proceeds some notional links will be broken and others will be firmed up to become actual links. At this point a combination of both the number of connection options, and the strength of the links involved, needs to be considered. An actual link is deemed strongest. Then comes a notional link. Last is a potential link i.e. a link that is not notional but can be made into an actual link by the proponent or, if this is not done, prevented from becoming an actual link by a framework barrier created by the opponent. The combination of two adjacent potential links is nearly but not quite as strong as one notional link, and the combination of two adjacent notional links is nearly but not quite as strong as one actual link. If necessary, the evaluation of links can be further refined by adding a small measure of strength contributed from the framework links that may be adjacent to the links under consideration, and again by using the pecking order of actual above notional above potential.

Rarely in the middle-game but slightly more often towards the end, the framework link evaluation will be insufficient. The deciding factor is then the local strength of the framework stone. This is basically an estimation of how easy it is to make sufficient eye space for life but may also take into account any price paid such as sacrifice of stones needed to ensure safety. During the earlier stages the indicators of liberties and the quantity of nearby empty space can be helpful.

Good judgement comes with experience. This can be speeded up by reviewing one's games and as an aid to this rather than for use in actual play, the following formulaic system for comparing the strength of framework stones is proffered:

+10

per potential link adjacent to framework stone

+30

per notional link adjacent to framework stone

+70

per actual link adjacent to framework stone

+1

per potential link adjacent to link adjacent to framework stone

+3

per notional link adjacent to link adjacent to framework stone

+7

per actual link adjacent to link adjacent to framework stone

+50

if framework stone dominates sufficient eye space for two definite eyes

+5

if framework stone dominates sufficient eye space for one definite eye

+1

per spacious liberty i.e. adjacent to the framework group and which the opponent cannot immediately force to be filled and also is at least three intersections from being solidly connected to an opponent stone