In a network supporting mobile communication devices, a mechanism to find the location of a device, wherever it may be, is needed. In this paper, we present a distributed algorithm for this purpose along with its formal specification and proof sketch. Inspired by our experiences with Wang's algorithm [9], one goal of this paper is to demonstrate that the process of formalization together with careful attention to abstraction and presentation can yield significant benefits in algorithm design. In this case, we obtained a more regular, general, and robust algorithm with a clearer description. An incidental contribution is a useful theorem for proving progress properties in distributed algorithms that use tokens
