“…Pseudo-relevance feedback methods assume the top-ranked documents to be relevant, but explicit or implicit relevance judgements from users may also be used (Anick, 2003;Keskustalo, Järvelin, & Pirkola, 2008;Vakkari, Jones, Macfarlane, & Sormunen, 2004;Xu & Croft, 1996). The recent interest of the semantic web community regarding models and methods related to ontologies have also sparked a renewed interest in using ontological information for relevance feedback (Bhogal, Macfarlane, & Smith, 2007;Rocha, Schwabe, & Aragao, 2004). In a language modeling setting, local query expansion has been applied to estimate query language models (Lafferty & Zhai, 2003;Tao & Zhai, 2006) or relevance models (Lavrenko & Croft, 2001); we elaborate on the latter in Section 3.…”