Artificial Intelligence and Soft Computing: Behavioral ... - Arteimi.info

of C3. If the constraints are listed in the program in a hierarchical manner
according to their priority, then a solution that satisfies the minimal constraint
from the priority list may be accepted. This is the basis of hierarchical
constraint logic programming.
19.6 Geometric Constraint Satisfaction
The CSP is not only useful for algebraic or logical problems but it may also
be employed to recognize objects from their geometric features [9-10]. The
features in the present context are junction labeling. In this book, we will
restrict our discussion to trihedral objects, i.e., objects having three
intersecting planes at each junction (vertex). However the concept may easily
be extended for polyhedral objects as well. For labeling a junction of a
trihedral object (vide fig.19.10), we require two types of formalism to mark
the edges meeting at the junctions.
.
i) Mark the boundary edges of the objects by arrowheads
ii) For each non boundary edge of the object, check whether it is convex or
concave. If convex, mark that edge by ‘+’ else by ‘-’.
A B
J C
I
H E D
G F
Fig 19.10: A typical trihedral object.
One question then naturally arises: how to test the convexity or concavity of
an edge. The following principle, in this regard, is worthwhile mentioning.
A
F
B
E
Fig. 19.11: Testing convexity of edge BE.
C
D