Annotation-based Document Retrieval with Four-Valued Probabilistic Datalog

The COLLATE system (collaboratory for annotation, indexing and retrieval of digitized historical archive material) provides film researchers with a collaborative environment in which historic documents about European films can be analysed, interpreted and discussed, using nested annotations and discourse structure relations among them. Annotations are metadata, and annotation threads form a hypertext containing positive and negative links, constituting a certain kind of context exploitable for document retrieval. In this paper, we discuss a solution for using annotations for information retrieval. To exploit annotation threads which consist of nested annotations and typed links between them, an annotation-based retrieval approach should have to cope with negative and contradictory statements. The nested annotation retrieval approach (NARA) is an approach addressing these issues. Based on this, we present NARAlog, an implementation using four-valued probabilistic datalog (FVPD), able to perform an in-depth analysis of annotation threads and to deal with contradictory statements.