Στο πλαίσιο της διοργάνωσης των σεμιναρίων του τμήματος θα πραγματοποιηθεί τη Δευτέρα 18/02/2019 και ώρα 12:00 στην αίθουσα Σεμιναρίων του Τμήματος Μηχανικών Η/Υ και Πληροφορικής, ομιλία με τίτλο “Object Summaries For Keyword Search”. Ομιλητής θα είναι ο Αν. Καθηγητής κ. Γεώργιος Φάκας, Department of Information Technology, Uppsala University, Sweden.

ΠΕΡΙΛΗΨΗ
The abundance and ubiquity of graphs (e.g., online social networks such as Google+ and Facebook; bibliographic graphs such as DBLP) necessitates the effective and efficient search over them. Given a set of keywords that can identify a data subject (DS), a recently proposed keyword search paradigm produces a set of object summaries (OSs) as results. An OS is a tree structure rooted at the DS node (i.e., a node containing the keywords) with surrounding nodes that summarize all data held on the graph about the DS.
OS snippets, denoted as size-l OSs, have also been investigated. A size-l OS is a partial OS containing l nodes such that the summation of their importance scores results in the maximum possible total score. However, the set of nodes that maximize the total importance score may result in an uninformative size-l OSs, as very important nodes may be repeated in it, dominating other representative information. In view of this limitation, we investigate the effective and efficient generation of two novel types of OS snippets, i.e., diverse and proportional size-l OSs. Namely, besides the importance of each node, we also consider its pairwise relevance to the other nodes in the OS and the snippet. We conduct an extensive evaluation on two real graphs (DBLP and Google+).