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

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Many optimization problems need to satisfy a set of constraints. For<br />

instance let the constraint C be given by C= (x+ y ≤ 4) ∧ (x >0) ∧(y>0) for<br />

all integer x, y. Suppose we want to maximize z = x 2 + y 2 . The possible<br />

assignments of (x ,y) are<br />

{x=1,y=1}, {x=1,y =3},<br />

{x=3,y=1}, {x=2,y=2}<br />

{x=2,y=1}, {x=1,y=2}.<br />

Out of these 6 (x, y) points {x=1,y=3} <strong>and</strong> {x=3,y=1} yield the highest<br />

value of z = x 2 + y 2 = 10. Such problems, where one has to optimize an<br />

objective function z = f(x, y), satisfying a set of constraints C, are called<br />

constraint optimization problems.<br />

Optimization problems need not be restricted to arithmetic constraints<br />

only. They may equally be useful for logical reasoning. For instance, consider<br />

the blocks world problem we considered in the chapter of intelligent planning.<br />

Suppose there are 4 objects on a table: 2 boxes, one cone, <strong>and</strong> one sphere.<br />

C<br />

D<br />

A B<br />

Fig. 19.5: The initial state of a blocks world problem.<br />

Suppose, we want to keep the cone at the highest position from the<br />

surface of the table. What should be the plan for object positioning that would<br />

lead us to this requirement?<br />

The initial state for the problem is given in fig. 19.5. We can represent<br />

this state by

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