Three reordering schemes have been used to produce narrow-banded hypertext matrices for cluster identification. Whereas the spectral-based methods (Fiedler and Correspondence Analysis) tend to produce matrices with smaller envelopes, the symbolic Reverse Cuthill-Mckee (RCM) method produces smaller bandwidths at a substantially reduced computational cost.

The reordered hypertext matrices facilitate the development of browsing tools for isolating document clusters of related information. Such tools are greatly needed to navigate large and/or distributed databases with hypertext links. The ability to identify (without necessarily retrieving) remote documents through their links to available (local) documents on a network is possible. In addition to browsing, indexing schemes based on term-document (or hypertext) matrices such as Latent Semantic Indexing (LSI) can exploit the reorderings presented for a more equitable distribution of nonzeros across processors or nodes of a network.

Future work on the reordering of hypertext matrices involves
(**i**) the consideration of much larger hypertext collections,
(**ii**) the development of a visual browser tool for the
X11 Release 5 Windows environment for extracting hypertext
clusters of related information,
(**iii**) the use of separator-based reorderings schemes
(e.g., nested dissection), and
(**iv**) the exploration of direct methods (as opposed to
iterative schemes such as Lanczos) for computing the
singular value decomposition (SVD) of banded hypertext
matrices.

Michael W. Berry (berry@cs.utk.edu)

Mon Jan 29 14:30:24 EST 1996