By: Dan Johnson & Jena Block

RDF definition What is Semantic web? Search Engine Example What is RDF? Triples Vocabularies RDF/XML Why RDF?

A standard for encoding metadata and other information on the Semantic Web

A project that aims to enable machines to do the searching, aggregating and combining of the Web's information without a human operator An extension to the Web that adds new data and metadata to existing Web documents, extending those documents into data An abstract intention to apply machine-exclusive meaning to the information on the web Documents that are not “Semantic” are in a language specific to people To make these documents “Semantic” we must apply a framework to the data within the document so the computer can understand it

Blah blah blah blah tapioca blah blah blah pudding. Chocolate pudding, blah blah blah tapioca shake. Blah blah blah blah. Blah blah blah blah tapioca pudding. Search: “Tapioca Pudding” Search Restaurants Menus Desserts Sides Search for: “Restaurants that serve Tapioca Pudding” Search Recipe Sites Desserts Sides Search for: “Recipes for Tapioca Pudding” Semantic Search Engine

Semantic search is narrower, more specific, and more efficient

Resource Description Framework Enables the encoding, exchange and reuse of structured metadata A general method to break down data into smaller pieces with rules of the semantics of those pieces A way of putting web data into a context which the computer can understand

We already have ways of putting web data into a context which the computer can understand Databases use tables XML uses hierarchies However, these techniques can be too restrictive

The data below is too flexible to be represented by a table or hierarchy so we use a graph To describe the data in the graph in terms that the computer can understand, we describe each relationship individually e.g. “vincent_donofrio” “starred_in” “the_thirteenth_floor”

RDF is a method used to break down knowledge into smaller pieces called triples Gives rules about the semantics to these pieces Subject, predicate, object – the subject and the object are two things in the world and the predicate is the relation between the two

my_housecouch has_a Subject Predicate Object

Using triple format, we can describe any series of relationships in a way that the computer can understand e.g. “ The quick brown fox jumped over the lazy dog ” Although we’ve described the relationships in the sentence, the computer still doesn’t know what these words or phrases actually mean, to solve this problem we must make a vocabulary SubjectPredicateObject Foxis_the_speedQuick Foxis_the_colorBrown Dogis_justLazy Foxjumped_overDog

Vocabulary (n) – a list of words and phrases of a language When we create an RDF file we need to define the terms we use We do this using a vocabulary built for the computer TermDefinition Dogan object Foxan object Quicka speed Browna color lazyan attribute is_the_speedgives a speed to an object is_the_colorgives a color to an object is_justgives an attribute to an object jumped_over gives the action/position relationship between two objects as one jumping over the other

We can use vocabularies that we build or we can use existing vocabularies published by someone else Dublin Core

The W3C specifications define an XML format to encode RDF <rdf:RDF xmlns:rdf=" xmlns:fd=" "quick" "brown" lazy

The RDF/XML format has the following rules: Root element must be Vocabularies are referenced using XML namespace The RDF triples are organized using the tag The subject is named in the about attribute The child nodes within the tag are the predicates Their content is the object “Dog” “is_just” “Lazy” lazy

RDF/XML is only one of many types of notation for RDF and is the only one that utilizes XML and XML namespace The major difference between to two is in the data model XML is hierarchical RDF is relational

Allows multiple users the freedom of their own format while maintaining interoperability RDF can be as descriptive as the English language while maintaining an organization that the computer can understand However, the question of how an application will retrieve these files has not yet been answered