Embedding semantic annotations within texts: the FRETTA approach

n order to make semantic assertions about the text content of a document we need a mechanism to identify and organize the text structures of the document itself. Such mechanism would closely resemble a document-oriented markup language and would be free of the classical constraints of an embedded markup language, having no limitations given by sequentiality, containment, or contiguity of text fragments. In the past years we developed EARMARK, our OWL proposal for expressing arbitrary semantic annota- tions about the structure and the text content of a document. In this paper we describe FRETTA, our mechanism for rendering arbitrary EARMARK annotations (including non-sequential, non-hierarchical and non-contiguous ones) in XML, bringing into a unifying framework a half dozen of syntactic tricks used in literature to handle overlapping structures in a strictly hierarchical language.