Experiments for HARD and Enterprise Tracks

1. HARD track The main theme in our participation in this year's HARD track was experimentation with the effect of lexical cohesion on document retrieval. Lexical cohesion is a major characteristic of natural language texts, which is achieved through semantic connectedness between words in text, and expresses continuity between the parts of text [7]. Segments of text which are about the same or similar subjects (topics) have higher lexical cohesion, i.e. share a larger number of words than unrelated segments. We have experimented with two approaches to the selection of query expansion terms based on lexical cohesion: (1) by selecting query expansion terms that form lexical links between the distinct original query terms in the document (section 1.1); and (2) by identifying lexical chains in the document and selecting query expansion terms from the strongest lexical chains (section 1.2).