12 Generating Expert Rules from Examples in PROLOG B. Arbab* D. Michie

It is assumed that Si are sorted in increasing order of s(Si). Non-linearities of four trees are shown in Figure 6. Ti is absolutely linear; thus its non-linearity measure is zero. T2 is very close to being a balanced tree: non-linearity one. T3 is preferred to T4, i.e. this function is sensitive to the location of non-linearity within a tree (the lower a non-linearity occurs in a tree the lower (better) its measure).