It is 9:00 PM, you are very tired, and you are settling down in a comfortable armchair with a book of conference proceedings. You are supposed to call your mother at 9:30. Infer that you would do well to set the alarm on your watch for 9:25.
Contributed by Ernie Davis ( davise@cs.nyu.edu), New York University, U.S.A. (19th September 1997)