Provenance refers to any information describing the production process of an end product,
which can be anything from a piece of digital data to a physical object. While this survey …

Large volumes of geo-tagged text objects are available on the web. Spatial keyword top-k
queries retrieve k such objects with the best score according to a ranking function that takes …

This work considers why-not questions in the context of top-k queries and score-based
ranking functions. Following the popular linear scalarization approach for multi-objective …

Web objects, often associated with descriptive text documents, are increasingly being geo-
tagged. A spatial keyword top-k query retrieves the best k such objects according to a …

Answering a Why-Not question consists in explaining why a query result does not contain
some expected data, called missing answers. This paper focuses on processing Why-Not …

Why-not and why questions can be posed by database users to seek clarifications on
unexpected query results. Specifically, why-not questions aim to explain why certain …

A top-k geo-social keyword (TkGSK) query retrieves the objects by considering spatial,
social, and textual constraints. After a user issues an initial TkGSK query and gets back its …

Abstract SPARQL, the W3C standard for RDF query languages, has gained significant
popularity in recent years. An increasing amount of effort is currently being exerted to …

With the continued proliferation of location-based services, a growing number of web-
accessible data objects are geo-tagged and have text descriptions. An important query over …

In data streaming, why-provenance can explain why a given outcome is observed but offers
no help in understanding why an expected outcome is missing. Explaining missing answers …