When Adrian, Buford, and Carter eat out, each orders either ham or pork. If Adrian orders ham, Buford orders pork. Either Adrian or Carter orders ham, but not both. Buford and Carter do not both order pork. Who could have ordered ham yesterday, pork today?
It is a rare event when a book of truly new logical puzzles is primed, but George Summers has now twice produced such an event. In New Puzzles in Logical Deduction he created 50 truly new puzzles. With new turns of thought, new subtleties of inference, he has here created 50 more! Even if you have not seen the basic situations before, you have never before had a chance to test your logic against the precision of scope of these.
The puzzles range in difficulty from the relatively simple examples at the beginning of the book to others, tricky, complex, and subtle enough to test the expert. Most are set in story form. Some are concerned with establishing identities from minimal clues. Others are based on cryptarithmetic, or the identification of numbers. While an occasional problem involves algebra, no special knowledge is required for most, no mathematics beyond high school, no training in traditional or symbolic logic. All that one need to them is the ability to think clearly and consecutively, and to pursue the puzzles in the most downright logical way.
Among the strongest features of Summers' book is the solutions section, which takes the reader through every step and every implication of the solutions. After seeing one solution, you cannot help but test your logic against the next puzzle in the book. There are even hints printed at the bottom of the page to stall somewhat the irresistible urge to turn to the answers. To our knowledge this material is unique.