the other hand, things shouldn't be so wishy-washy that nothing has any
meaning at all, either. The trick is to know when and how to slip one
concept into another.
An extremely interesting set of examples where slipping from one
description to another is the crux of the matter is given in Bongard
problems 85-87 (Fig. 125). BP 85 is rather trivial. Let us assume that our
program identifies "line segment" in its preprocessing stage. It is relatively
simple for it then to count line segments and arrive at the difference
FIGURE 125. Bongard problems 85-87. [From M. Bongard, Pattern Recognition.]