Part Two 315
Answer 13-1
The maximal domain is set A. The co-domain is set D. The essential domain is set B. The
range is set C.
Question 13-2
In Fig 20-1, the five points within set C represent the entire set. On that basis, what can we
say about the mapping?
Answer 13-2
The mapping is onto set C. That is, it is a surjection.
Question 13-3
In Fig 20-1, note that each of the points in set B maps to a single point in set C. What can we
say about the mapping on this basis?
Answer 13-3
The mapping is one-to-one. That is, it is an injection.
Question 13-4
In Fig 20-1, suppose that each point in set B maps to a single point in set C, and vice-versa.
On this basis, and according to what we know so far about the points and the sets, what type
of mapping is this?
A
B
C
D
Figure 20-1 Illustration for Questions and Answers 13-1
through 13-8.