After 20 minutes of waiting outside the baggage claim area for your friend to pick you up, you decide to go inside the airport terminal and phone her. standing a short distance from you is a kind-looking older woman. would you mind watching my luggage so i can go make a quick phone call? " you ask politely. i'd be happy to watch it for you," she replies, "my ride is not coming for another half-hour." when you return less than five minutes later, the old lady and your luggage (including your laptop) are gone. this example illustrates one of the problems associated with: