  Controlled topical vocabularies (CVs) are built into information systems to
aid browsing and retrieval of items that may be unfamiliar, but it is unclear
how this feature should be integrated with standard keyword searching. Few
systems or scholarly prototypes have attempted this, and none have used the
most widely used CV, the Library of Congress Subject Headings (LCSH), which
organizes monograph collections in academic libraries throughout the world.
This paper describes a working prototype of a Web application that concurrently
allows topic exploration using an outline tree view of the LCSH hierarchy and
natural language keyword searching of a real-world Science and Engineering
bibliographic collection. Pilot testing shows the system is functional, and
work to fit the complex LCSH structure into a usable hierarchy is ongoing. This
study contributes to knowledge of the practical design decisions required when
developing linked interactions between topical hierarchy browsing and natural
language searching, which promise to facilitate information discovery and
exploration.
