Logical spreadsheets are spreadsheets in which formulas are written as logical constraints rather than function definitions. Allowing logical constraints in spreadsheets substantially increases their utility. At the same time, it poses interesting technical challenges, notably the representation of logical constraints (both static and dynamic), query and update in the face of data incompleteness and inconsistency, and support for collaborative work on distributed spreadsheets. In this presentation, we describe logical spreadsheets in detail and offer some approaches to dealing with these underlying challenges.
While logical spreadsheet technology is useful in specialized applications, it is even more useful as a general technology for the World Wide Web, turning ordinary Web forms into logical forms (sometimes called websheets). Moreover, the concept and technology of collaborative websheets can be further generalized to collaborative management of arbitrary logical databases. We close with thoughts about how this generalized technology can be used to produce a key component of the Semantic Web, viz. a World Data Web in which concepts and relationships replace documents and links, in which rules replace code, and in which query and update replace keyword search and file management.