1.1 d

Exercise 1.1. Assume that A is a book with 500 pages and B a book with 1000 pages. Give an informal proof of each of the following, using the techniques discussed in this section. Mathematical Logic 10 ASON TURNER (a) If a book is shorter than A, it is also shorter than B. (This is equivalent to: every book that is shorter than A is also shorter than B.) (b) Every book longer than A but shorter than B has more than 500 pages but less than 1000 pages. (c) No book is longer than B but shorter than A (d) If a book is not between A and B in length, then it either has 500 pages or less, or it has 1000 pages or more