title: Extraction of temporal networks from term co-occurrences in online textual sources.
abstract: A stream of unstructured news can be a valuable source of hidden relations between different entities, such as financial institutions, countries, or persons. We present an approach to continuously collect online news, recognize relevant entities in them, and extract time-varying networks. The nodes of the network are the entities, and the links are their co-occurrences. We present a method to estimate the significance of co-occurrences, and a benchmark model against which their robustness is evaluated. The approach is applied to a large set of financial news, collected over a period of two years. The entities we consider are 50 countries which issue sovereign bonds, and which are insured by Credit Default Swaps (CDS) in turn. We compare the country co-occurrence networks to the CDS networks constructed from the correlations between the CDS. The results show relatively small, but significant overlap between the networks extracted from the news and those from the CDS correlations.
authors.affiliation: Theoretical Physics Division, Rudjer Bošković Institute, P.O.Box 180, HR-10002, Zagreb, Croatia.
authors.forename: Marko
authors.initials: M
authors.lastname: Popović
authors.affiliation: Theoretical Physics Division, Rudjer Bošković Institute, P.O.Box 180, HR-10002, Zagreb, Croatia; Catholic University of Croatia, Zagreb, Croatia.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Štefančić
authors.affiliation: Jožef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Borut
authors.initials: B
authors.lastname: Sluban
authors.affiliation: Jožef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Petra
authors.initials: P
authors.lastname: Kralj Novak
authors.affiliation: Jožef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Miha
authors.initials: M
authors.lastname: Grčar
authors.affiliation: Jožef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Igor
authors.initials: I
authors.lastname: Mozetič
authors.affiliation: IMT Alti Studi Lucca, Lucca, Italia.
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Puliga
authors.affiliation: Theoretical Physics Division, Rudjer Bošković Institute, P.O.Box 180, HR-10002, Zagreb, Croatia.
authors.forename: Vinko
authors.initials: V
authors.lastname: Zlatić
mesh_terms: D000465:Algorithms; D003195:Computer Communication Networks; D006801:Humans; D008962:Models, Theoretical; D009862:Online Systems