A model and a visual query language for structured text

We present a new model to query document databases by content and structure. The main merits of the model are: it allows rich structure in the documents; the query algebra is intuitive (moreover, complemented by a visual query language) and powerful; it is efficiently implementable; it can be built on top of a traditional indexing system or even with no index at all; it is strongly oriented to user-definable relevance ranking instead of boolean logic; and it allows flexible visualization of results in terms of structure, contents and highlighting of user-defined important parts in the query