In ontology-based data access (OBDA), database querying is enriched with an ontology that provides domain knowledge and additional vocabulary for query formulation. We identify query emptiness and predicate emptiness as two central reasoning services in this context. Query emptiness asks whether a given query has an empty answer over all databases formulated in a given vocabulary. Predicate emp...

AGGREGO SEARCH offers a novel keyword-based query solution for end users in order to retrieve precise answers from semantic data sources. Contrary to existing approaches, AGGREGO SEARCH suggests grammatical connectors from natural languages during the query formulation step in order to specify the meaning of each keyword, thus leading to a complete and explicit definition of the intent of the s...

Query patterns enable effective information tools and provide guidance to users interested in posing complex questions about objects. Semantically, query patterns represent important questions, while syntactically they impose the correct formulation of queries. In this paper we address the development of query patterns at successive representation layers so as to expose dominant information req...

In this paper we investigate the effectiveness of topic-independent query templates as a tool for assisting users in articulating their information needs. We hypothesize that topic-independent query templates can help users with complex information needs to express their requirements more accurately and in greater detail. We developed a set of query templates representing general semantic relat...

Query formulation is a key aspect of information retrieval, contributing to both the efficiency and usability of many semantic applications. A number of query languages, such as SPARQL, have been developed for the Semantic Web; however, there are, as yet, few tools to support end users with respect to the creation and editing of semantic queries. In this paper we introduce NITELIGHT, a Web-base...

The adoption of a visual interface can simplify the query formulation process in DBMSs by enabling naive users to interact with a friendly environment. In this work we propose a visual query language based on a diagrammatic paradigm, used for both data and query representation. The external data model is called vision and is made up of the visual primitives of concept and association. The exter...

The so called Visual Query Systems try to support unskilled users in formulating complex queries to highly structured databases, by providing graphic paradigms for visualizing the database conceptual models, and by allowing to build queries through visual interactions. In the present paper we propose a paradigm, for supporting the user in building sophisticated queries, based on a uniform graph...

Visual query interfaces enable users to construct queries without special training in the syntax and semantics of a query language. Traditionally, efforts toward such interface design and devising efficient query processing techniques are independent to each other. This is primarily due to the chasm between HCI and data management fields as since their inception, rarely any systematic effort is...

In image retrieval systems, user information needs is expressed using multiple types of query. Unfortunately, due to user subjectivity perception to visual features and semantic depths of images, the conventional query submitted to the system encounter difficulties to identify user information need. The blooming of interest in semantic image retrieval requires current research direction to be m...