The Bulletin of Symbolic Logic primarily publishes two types of papers, articles and communications. Articles present topics of broad interest that should be accessible to a large audience. They can be purely expository, survey, or historical articles, or they may contain, in addition, new ideas or results or new approaches to old ones. Communications are announcements of important new results and ideas. They are expected to include a description of the new work, as well as enough history, background, and explanation to make the significance of the work apparent to a wide audience.