  Keyphrase is an efficient representation of the main idea of documents. While
background knowledge can provide valuable information about documents, they are
rarely incorporated in keyphrase extraction methods. In this paper, we propose
WikiRank, an unsupervised method for keyphrase extraction based on the
background knowledge from Wikipedia. Firstly, we construct a semantic graph for
the document. Then we transform the keyphrase extraction problem into an
optimization problem on the graph. Finally, we get the optimal keyphrase set to
be the output. Our method obtains improvements over other state-of-art models
by more than 2% in F1-score.
