Conceptual Graphs Are Also Graphs -- Argumentation-Based Paraconsistent Logics -- Towards a Framework for Learning from Networked Data -- Games on Graphs -- A Partial-Closure Canonicity Test to Increase the Efficiency of CbO-Type Algorithms -- On Conceptual Graphs and Explanation of Query Answering under Inconsistency -- Defining Key Semantics for the RDF Datasets: Experiments and Evaluations -- A Framework for Qualitative Representation and Reasoning about Spatiotemporal Patterns -- Combining Restricted Boltzmann Machine and One Side Perceptron for Malware Detection -- Knowledge Management and Human Trafficking: Using Conceptual Knowledge Representation, Text Analytics and Open-Source Data to Combat Organized Crime -- Default Reasoning Implementation in CoGui -- Extracting Threshold Conceptual Structures from Web Documents -- A Formal Topology of Web Classification -- Specifying Well-Formed Part-Whole Relations in Coq -- Automatic Extraction of Semantic Relations by Using Web Statistical Information -- Efficient Representation of Extensional Constraints -- On the Usability of Random Indexing in Patent Retrieval -- Teaching Syllogistics Using Conceptual Graphs -- Principles of Regulated Activation Networks -- Computing Concept Lattices from Very Sparse Large-Scale Formal Contexts -- Swip: A Natural Language to SPARQL Interface Implemented with SPARQL -- Environmental Scanning and Knowledge Representation for the Detection of Organised Crime Threats -- Combining Business Intelligence with Semantic Technologies: The CUBIST Project -- FCA-Based Recommender Models and Data Analysis for Crowdsourcing Platform Witology -- Conceptual Structures in Leading and Best Enterprise Practices -- Eco-Efficient Packaging Material Selection for Fresh Produce: Industrial Session.

This book constitutes the proceedings of the 21st International Conference on Conceptual Structures, ICCS 2014, held in Iaşi, Romania, in July 2014. The 17 regular papers and 6 short papers presented in this volume were carefully reviewed and selected from 40 and 10 submissions, respectively. The topics covered are: conceptual structures, knowledge representation, reasoning, conceptual graphs, formal concept analysis, semantic Web, information integration, machine learning, data mining and information retrieval.