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

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The recognition problem is the present content needs to check the<br />

geometric feature of the object under test <strong>and</strong> determine the object by<br />

satisfying the premises of one of the above three constraints.<br />

While dealing with CSP we should consider the following three issues:<br />

i) whether the constraints are satisfiable, i.e., does the<br />

problem has solutions that satisfy all the constraints?<br />

ii) simplification of the constraints by equivalent simpler<br />

ones,<br />

iii) optimization of the solution based on some other criteria, if<br />

more than one solution exists.<br />

19.2 Formal Definitions<br />

We now present a few definitions, which will be referred to throughout the<br />

chapter.<br />

Definition 19.1: Constraints are mathematical/ logical relationships among<br />

the attributes of one or more objects.<br />

To underst<strong>and</strong> the above definition, let us consider the ‘make-changes of 10$’<br />

problem, where the 1$, 2$, 5$ notes are objects <strong>and</strong> their counts are the<br />

attributes in the problems. Thus the mathematical relationship among them is<br />

the expression ∑ ci xi = 10$ , which is the constraint.<br />

∃xi<br />

Definition 19.2: The legitimate set of operators like ‘+’ , ‘* ’, ‘∧’ or ’∨’<br />

<strong>and</strong> the type of the variables <strong>and</strong> their domains, the type of functions used<br />

<strong>and</strong> their range <strong>and</strong> the arguments of the operators are specified by a<br />

domain, called constraint domain.<br />

Formally, the constraint domain D is a 5 tuple, given by<br />

D={v, f, op, d, r}<br />

where v denotes the set of variables,<br />

f denotes the set of functions,<br />

op st<strong>and</strong>s for the set of legal operators to be used on variables or<br />

functions,<br />

d is the domain of variable, <strong>and</strong><br />

r is the range of the functions employed in the constraints.

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