In combinatorial optimization, a mathematical discipline, the traveling tourist problem is similar to the traveling salesman problem: a tourist wishes to see all monuments (nodes) in a city, and so must visit each monument or a neighbour thereof (it is assumed that a monument is visible from any of its neighbours – the edges therefore represent lines of sight). The resulting walk will therefore visit a subset of all nodes in the graph.
Guha, Sudipto; Khuller, Samir (April 28–30, 1997). "Connected Facility Location Problems". DIMACS Workshop on Network Design: Connectivity and Facilities Location. American Mathematical Society. pp. 180. http://books.google.ca/books?id=IMmuF0RZk1MC&pg=PA180.