A distributed system is one in which the failure of a computer you didn't even know existed can render your own computer unusable. -Leslie Lamport. Leslie Lamport is a computer scientist and mathematician best known for his work with distributed systems. In fact, Dr. Lamport?s research contributions laid the foundations for the theory of distributed systems. He currently works in Microsoft Research where most of his time is spent developing formal semantics (with mathematical logic) for specifying and reasoning about algorithms. Here, Dr. Erik Meijer, computer scientist and programming language/library designer, sits down with Dr. Lamport to discuss several aspects of Dr. Lamport's body of work in computer science. Dr. Lamport's TLA, the Temporal Logic of Actions, is a logic for specifying and reasoning about concurrent and reactive systems. TLA+ is the latest incarnation of this formal specification toolset....