Скачать или смотреть 02. Resource Description Framework (RDF): Graphs, Triples, and the Semantic Web's Data Model

This video introduces the Resource Description Framework (RDF), a formal language essential for describing structured information on the Web. RDF's primary goal is to enable software applications to exchange data while preserving its original meaning. Consequently, RDF is widely considered the basic representation format for developing the Semantic Web.

Key Structural and Technical Aspects Covered:
• Graph Structure: RDF models data as a directed graph, a collection of nodes linked by directed, labeled edges. This graph structure is preferred over hierarchical tree structures (like XML) because graphs are inherently more suitable for describing general relationships between resources and integrating decentralized data from multiple sources across the World Wide Web.
• RDF Triples: The entire RDF graph is typically represented as a collection of its edges. Each edge corresponds to a single RDF triple: Subject–Predicate–Object. Each part of the triple can be a URI, and the object can also be a literal.
• Identification (URIs): To uniquely identify resources (both nodes and edges) and resolve data ambiguity (e.g., the same resource having different identifiers), RDF uses URIs (Uniform Resource Identifiers). These identifiers serve purely for identification, even for objects that are not web-accessible (URNs).
• Data Values (Literals): Concrete data values, such as numbers, dates, or strings, are represented using literals. The interpretation of a literal depends on its associated datatype, which are often identified using URIs from XML Schema datatypes for compatibility. Literals cannot be used as the origin or label of edges in the graph.
• Serialization and Syntax: While diagrams are intuitive for small examples, large RDF datasets require a textual representation, known as serialization, for computer processing and storage. Key serialization formats discussed include Turtle (Terse RDF Triple Language), a formal W3C standard known for being relatively human-readable, and RDF/XML, the main syntax in practice due to widespread support for XML processing libraries.
• Complex Modeling: The video also addresses how RDF handles many-valued (ternary or n-ary) relationships by introducing auxiliary nodes. These structural helper nodes often do not require a globally referable URI and are represented using Blank Nodes.

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This video content was generated and structured using notebooklm, drawing exclusively upon lecture excerpts detailing Semantic Technologies and Enterprise Modelling Ontologies.

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