These
transactions publish research in computer-based methods of computational
collective intelligence (CCI) and their applications in a wide range of fields
such as the semantic Web, social networks, and multi-agent systems. TCCI
strives to cover new methodological, theoretical and practical aspects of CCI
understood as the form of intelligence that emerges from the collaboration and
competition of many individuals (artificial and/or natural). The application of
multiple computational intelligence technologies, such as fuzzy systems,
evolutionary computation, neural systems, consensus theory, etc., aims to
support human and other collective intelligence and to create new forms of CCI
in natural and/or artificial systems. This twenty-first issue contains 7 carefully
selected and revised contributions.

Keyword-based
Search over Databases: A Roadmap for a Reference Architecture Paired with an
Evaluation Framework.- Entity-based
Keyword Search in Web Documents.- Evaluation
of Keyword Search in Affective Multimedia Databases.- Subject-related
Message Filtering in Social Media Through Context-enriched Language Models.- Improving
Open Information Extraction for Semantic Web Tasks.- Searching Web 2.0 Data
through Entity-Based Aggregation.