QARTS

Rob van Zeijst in one of his Magic of Go columns outlines his "QARTS" system, in which he quantifies thickness and aji.

QARTS is an acronym for Quantitative Analysis of Relative Territory and Strength.

The idea is to

• assign -20 points to a weak group without eyes, and
• 0 to -10 points for a weakish group with room for one eye

(depending on whether or not the group is capable of making some territory in addition to the required second eye).
Together with counting established territory in the usual fashion,
this is a tool for judging reinforcements or the relative merits of an invasion versus a reducing move.

Yomiuri 'Magic of Go' article 420

Notes:

Some relevant pages from the column are numbers 117, 129, 183, 184. These are no longer available at the Yomiuri site.