Vocabularies, Schemas, Ontologies -- Requirements for and Evaluation of User Support for Large-Scale Ontology Alignment -- RODI: A Benchmark for Automatic Mapping Generation in Relational-to-Ontology Data Integration -- VocBench: a Web Application for Collaborative Development of Multilingual Thesauri -- Leveraging and Balancing Heterogeneous Sources of Evidence in Ontology Learning -- Reasoning -- A Context-Based Semantics for SPARQL Property Paths over the Web -- Distributed and Scalable OWL EL Reasoning -- Large scale rule-based Reasoning using a Laptop -- RDF Digest: Efficient Summarization of RDF/S KBs -- Linked Data -- A Comparison of Data Structures to Manage URIs on the Web of Data -- Heuristics for Fixing Common Errors in Deployed schema.org Microdata -- Semantic Web and Web Science -- LOD-based Disambiguation of Named Entities in @tweets through Context enrichment -- Knowledge Enabled Approach to Predict the Location of Twitter Users -- Semantic Data Management, Big data, Scalability -- A Compact In-Memory Dictionary for RDF data -- Quality Assessment of Linked Datasets using Probabilistic Approximations -- Cooperative Techniques for SPARQL Query Relaxation in RDF Databases -- HDT-MR: A Scalable Solution for RDF Compression with HDT and MapReduce -- Processing Aggregate Queries in a Federation of SPARQL Endpoints -- A survey of HTTP caching implementations on the open Semantic Web -- Query Execution Optimization for Clients of Triple Pattern Fragments -- Natural Language Processing and Information Retrieval LIME: the Metadata Module for OntoLex -- Learning a Cross-Lingual Semantic Representation of Relations Expressed in Text -- HAWK Hybrid Question Answering using Linked Data -- Machine Learning -- Automating RDF Dataset Transformation and Enrichment -- Semi-supervised Instance Matching Using Boosted Classifiers -- Assigning Semantic Labels to Data Sources -- Inductive Classification through Evidence-based Models and their Ensembles -- Mobile Web, Internet of Things and Semantic Streams -- Standardized and Efficient RDF Encoding for Constrained Embedded Networks -- Services, Web APIs, and the Web of Things SPSC: Efficient Composition of Semantic Services in Unstructured P2P Networks -- Data as a Service: The Semantic Web Redeployed -- Cognition and Semantic Web -- On Coherent Indented Tree Visualization of RDF Graphs -- Gagg: A Graph Aggregation Operator -- FrameBase: Representing N-ary Relations using Semantic Frames -- Human Computation and Crowdsourcing -- Towards hybrid NER: a study of content and crowdsourcing-related performance factors -- Ranking Entities in the Age of Two Webs, An Application to Semantic Snippets -- In-Use Industrial Track -- Troubleshooting and Optimizing Named Entity Resolution Systems in the Industry -- Using Ontologies For Modeling Virtual Reality Scenarios -- Supporting Open Collaboration in Science through Explicit and Linked Semantic Description of Processes -- Crowdmapping Digital Social Innovation with Linked data -- Desperately searching for travel offers? Formulate better queries with some help from Linked Data -- Towards the Linked Russian Heritage Cloud: Data enrichment and Publishing -- From Symptoms to Diseases - Creating the Missing Link -- Using semantic web technologies for enterprise architecture analysis -- PADTUN - Using Semantic Technologies in Tunnel Diagnosis and Maintenance Domain.

This book constitutes the refereed proceedings of the 12th Extended Semantic Web Conference, ESWC 2014, held in Anissaras, Portoroz, Slovenia, in May/June 2015. The 43 revised full papers presented together with three invited talks were carefully reviewed and selected from 164 submissions. This program was completed by a demonstration and poster session, in which researchers had the chance to present their latest results and advances in the form of live demos. In addition, the PhD Symposium program included 12 contributions, selected out of 16 submissions. The core tracks of the research conference were complemented with new tracks focusing on linking machine and human computation at web scale (cognition and Semantic Web, Human Computation and Crowdsourcing) beside the following subjects Vocabularies, Schemas, Ontologies, Reasoning, Linked Data, Semantic Web and Web Science, Semantic Data Management, Big data, Scalability, Natural Language Processing and Information Retrieval, Machine Learning, Mobile Web, Internet of Things and Semantic Streams, Services, Web APIs, and the Web of Things, Cognition and Semantic Web, Human Computation and Crowdsourcing,  and In-Use Industrial Track as well.