In Example 1.2-4, describe A c B c . EXAMPLE 4. Let A={(x,y) : x 0} and B = {(x,y)

In Example 1.2-4, describe A^cB^c.

EXAMPLE 4. 

Let A={(x,y) ∈ Ω : x ≥ 0} and B = {(x,y) ∈ Ω : y ≥ 0}. The situation is illustrated in Fig. 3. The set A corresponds to the right half of the disk (x’s are positive) and the set B to the top half of the disk (y’s are positive). The whole shaded region corresponds to A∪B, the strongly shaded to AB. ▢

-r y -r FIGURE 3. r X