Joachim Selke

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By incorporating human workers into the query execution process crowd-enabled databases facilitate intelligent, social capabilities like completing missing data at query time or performing cogni-tive operators. But despite all their flexibility, crowd-enabled databases still maintain rigid schemas. In this paper, we extend crowd-enabled databases by(More)
Recent years brought tremendous advancements in the area of automated information extraction. But still, problem scenarios remain where even state-of-the-art algorithms do not provide a satisfying solution. In these cases, another aspiring recent trend can be exploited to achieve the required extraction quality: explicit crowdsourcing of human intelligence(More)
The storage, management, and retrieval of entity-related data has always been among the core applications of database systems. However, since nowadays many people access entity collections over the Web (e.g., when searching for products, people, or events), there is a growing need for integrating unconventional types of data into these systems, most notably(More)
Until recently algorithms continuously gained free performance improvements due to ever increasing processor speeds. Unfortunately, this development has reached its limit. Nowadays, new generations of CPUs focus on increasing the number of processing cores instead of simply increasing the performance of a single core. Thus, sequential algorithms will be(More)
Performing effective preference-based data retrieval requires detailed and preferentially meaningful structurized information about the current user as well as the items under consideration. A common problem is that representations of items often only consist of mere technical attributes, which do not resemble human perception. This is particularly true for(More)
When issuing user-specific queries, users often have a vaguely defined information need. Skyline queries identify the most " interesting " objects for users' incomplete preferences, which provides users with intuitive query formulation mechanism. However, the applicability of this intuitive query paradigm suffers from a severe drawback. Incomplete(More)
—Online shopping sites are faced with a significant problem: When offering experience products, i.e., products that lack a helpful description in terms of easily accessible factual properties (e.g., wine, cigars, and movies), a lot of work and time needs to be invested to provide such information. Two very popular approaches are the introduction of(More)
When issuing user-specific queries, users often present vague and imprecise information needs. Skyline queries with an intuitive query formulation mechanism identify the most interesting objects for incomplete user preferences. However, the applicability of skyline queries suffers from a severe drawback because incomplete user preferences often lead to an(More)
Skyline queries have become commonplace in many applications. The main problem is to efficiently find the set of Pareto-optimal choices from a large amount of database items. Several algorithms and indexing techniques have been proposed recently, but until now no indexing technique was able to address all problems for skyline queries in realistic(More)