Question

b. which of the following describes the set of important books? a. it is well defined. it is possible to list all of the important books in the world b. it is not well defined. there is no clear meaning of \books.\ c. it is well defined. for a given book, it is possible to tell whether it is important d. it is not well defined. there is no clear meaning of \important.\ e. it is not well defined. although there is a clear meaning of \books,\ it is not possible to tell whether a thing is a book f. it is well defined. for a given thing, it is possible to tell whether it is a book

Explanation:

To determine the set of important books, we analyze the options:

• Option A: Listing all important books is impossible (infinite or subjective), so wrong.
• Option B: "Books" is well - defined, so wrong.
• Option C: "Books" is clear, but "important" is subjective. For a book, we can't objectively tell if it's important, so the set is not well - defined. This matches.
• Option D: "Books" is clear, so wrong.
• Option E: "Books" is clear, so wrong.
• Option F: "Books" is clear, so wrong.

Answer:

C. It is well defined. For a given book, it is possible to tell whether it is important