John Mackey Teaching Professor Office 4005 Gates and Hillman Centers Email jmackey@andrew.cmu.edu Phone (412) 268-6881 Department Computer Science Department Administrative Support Person Rosemary Battenfelder Biography I like to hunt for elusive mathematical objects having special properties. For example, assuming that every pair of people are either acquaintances or strangers, it is not known whether it is possible to have a party of 43 people at which no five people are mutual acquaintances and no five people are mutual strangers. It may be fun for you to construct the largest conceivable party at which no three people are mutual acquaintances and no three people are mutual strangers.