Text Annotation Graphs: Annotating Complex Natural Language Phenomena

This paper introduces a new web-based software tool for annotating text, Text Annotation Graphs, or TAG. It provides functionality for representing complex relationships between words and word phrases that are not available in other software tools, including the ability to define and visualize relationships between the relationships themselves (semantic hypergraphs). Additionally, we include a visualization mode in which annotation subgraphs, or semantic summaries, are used to show relationships outside of the sequential context of the text itself. These subgraphs can be used to quickly find similar structures within the current document or external annotated documents. TAG was initially developed to support information extraction tasks on a large database of biomedical articles. However, our software is flexible enough to support a wide range of annotation tasks for many domains. Examples are provided that showcase TAG's capabilities