Transhierarchy

Abstract

Transhierarchy is a method of navigating hypertext within a stable, hierarchical user interface. In a transhierarchy, a standard tree view is generated by traversing outbound links from a given node. Inbound links and their descendants are transcluded into the hierarchy, allowing continuous navigation to cross-referenced nodes. Transhierarchy is a practical solution to the problem of how to represent a directed graph in a strict hierarchy. It preserves connectivity, provides context during navigation, and is visually compact, making it a viable method for navigating hypertext on mobile devices. It does not require additional semantics, such as typed links. We explore the history of navigating hypertext via hierarchical views, present an implementation of transhierarchy in the first author's hypertext system, em, and survey its use in several pieces of commercial outliner software today.