Semantic Search - bounswe/bounswe2024group11 GitHub Wiki

Semantic search searches the information based on the meaning and the context of the query, unlike lexical search, which searches for the literal matches of the query.
Semantic search retrieves information from richly structured data sources like ontologies and XML as found on the Semantic Web.

Ontology describes concepts, relationships between entities, and categories of things.

XML allows for storing, communicating, and reconstructing arbitrary data. XML standardizes information exchange between two different systems.

Semantic Web

The Semantic Web, which aims to make Internet data machine-readable, is an extension of the World Wide Web. To achieve this goal the data on the Internet must be encoded semantically.
Technologies like Resource Description Framework (RDF) and Web Ontology Language (OWL) are used to formally represent information about the data, namely metadata.

Semantic queries work on named graphs, linked data, or triples. This enables the query to process the actual relationships between information and infer the answers from the network of data.

In the named graphs, a set of Resource Description Framework statements that constitute a graph are labeled using a URI. This allows us to attach a description, context, and information (or other such metadata) to each node of the graph.

A semantic triple, or RDF triple or simply triple, is the atomic data entity in the Resource Description Framework (RDF) data model. As its name indicates, a triple is a sequence of three entities that codifies a statement about semantic data in the form of subject–predicate–object expressions (e.g., "Bob is 35", or "Bob knows John").
The components of a triple, such as the statement "The sky has the color blue", consist of a subject ("the sky"), a predicate ("has the color"), and an object ("blue").

Semantic triplet represents the information in a way that machines can understand it easily. If every part of an RDF triple is individually addressable by URIs, the previous example "Bob knows John" can be represented in RDF as:

SPARQL (a recursive acronym for SPARQL Protocol and RDF Query Language) is an RDF query language. SPARQL can retrieve and manipulate data stored in RDF format.
Semantic queries are remarkably similar to database queries because they are precise relational-type operations. They work on structured data and can utilize comprehensive features like operators (like >, < and =), namespaces, pattern matching, subclassing, transitive relations, semantic rules, and contextual full-text search.