Fill in each blank with the word most or least.

a. A function F is one-to-one if, and only if, each element in the co-domain of F is the image of at one element in the domain of F.
b. A function F is onto if, and only if, each element in the co-domain of F is the image of at one element in the domain of F.

(a)

To fill:

A function F is one-to-one if, and only if, each element in the co-domain of F is the

image of at_________one element in the domain of F.

By the definition of one-to-one:

If two elements in the domain have the same image, then the two elements are the same. This then implies that each element in the codomain is the image of at most one element in the domain...

(b)

To Fill:

A function F is onto if, and only if, each element in the co-domain of F is the image of

at_________one element in the domain of F.