Davide Martinenghi

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Data sources on the web are often accessible through web interfaces that present them as relational tables, but require certain attributes to be mandatorily selected, e.g., via a web form. In a scenario where we integrate a set of such sources, and we pose queries over them, the values needed to access a source may have to be retrieved from other sources(More)
Where can I attend an interesting database workshop close to a sunny beach? Who are the strongest experts on service computing based upon their recent publication record and accepted European projects? Can I spend an April weekend in a city served by a low-cost direct flight from Milano offering a Mahler’s symphony? We regard the above queries as(More)
This paper investigates diversity queries over objects embedded in a low-dimensional vector space. An interesting case is provided by spatial Web objects, which are produced in great quantity by location-based services that let users attach content to places, and arise also in trip planning, news analysis, and real estate scenarios. The targeted queries aim(More)
Ranking queries report the top-<i>K</i> results according to a user-defined scoring function. A widely used scoring function is the weighted summation of multiple scores. Often times, users cannot precisely specify the weights in such functions in order to produce the preferred order of results. Adopting uncertain/incomplete scoring functions (e.g., using(More)
Unlike relational tables in a database, data sources on the Web typically can only be accessed in limited ways. In particular, some of the source fields may be required as input and thus need to be mandatorily filled in order to access the source. Answering queries over sources with access limitations is a complex task that requires a possibly recursive(More)
Mashup languages offer new graphic interfaces for service composition. Normally, composition is limited to simple services, such as RSS or Atom feeds, but users can potentially use visual mashup languages for complex service compositions, with typed parameters and well-defined I/O interfaces. Composing search services introduces new issues, however, such as(More)