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

program, all constraints are equally useful for finding viable solutions for the
problem. However, there exist situations, when no solution is found that
satisfies all the constraints. For handling these type of problems, the strengths
S i of the constraints Ci are attached with them in the program clauses as
presented below:
P (t) ← Q1 (t), Q2(t),…..,Qm(t), S1C1(t),S2C2 (t),……,SnCn(t).
Logic programs built with such type of clauses are called Hierarchical
Constraint Logic Programs (HCLP) [11].
We now illustrate the formulation of an HCLP and the approach to its
solution for the problem of editing a table on a computer screen in order to
keep it visually appealing.
Here, the spacing between two successive lines is a variable, whose
minimum value, for obvious reason, is greater than zero. However, we want it
to be less than 10. We also prefer that the table fit on a single page of 30
lines. Further, there could be a default space of 5 lines, i.e., if other
constraints are satisfiable, then one may attempt to satisfy the default
constraint.
Let us define the strength of the constraints into following 4 levels,
essential,
strongly preferred,
preferred,
default.
The logic program for the above problem is presented below.
Table (page-length, type-size, no-of-lines, space) ←
essential (space + type-size) * no-of-lines = page-length,
essential space >0,
strongly preferred space < 10,
preferred page-length