8/03/2005
Semantic Web Introduction
Here's a presentation I put together a while back on the Semantic Web. It is just an intro -- nothing indepth.
The Semantic Web The Problem There is a lot of information on the web. 532,897 Terabytes of data in 2002 Approximately 40 million files How can we find what we are looking for? Current Search Engines “Which pages contain the term ______?” Solution The Semantic Web
"The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.“ [1] The Semantic Web will provide semantics for web resources Semantic Web Search Engines “What’s the temperature in Boston?” “What’s the most effective headache medicine?” “Who has the cheapest hotel in the downtown Washington DC area?” [1] Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001
RDF Today’s web is implemented by URIs, HTTP, and HTML. The Semantic Web is built with URIs, HTTP, and RDF. RDF is Resource Description Framework. If HTML can create a relationship between two items
then RDF can create the following relationship
jessica,name,“Jessica Owensby-Sandifer”.
jessica,knows,john.
john,employer,BigCompany.
Wow! Is this making a database out the web or what? Yes.
”fieldValue”
One way to think of what researchers are trying to do with the Semantic web is the query. Rather than searching or browsing the web, we want now to be able to query, like one would a database, the web.
Deficiencies of XML But I could do that with XML. XML… provides no means of validating object semantics even if these are declared informally in an XML DTD is a poor language for data modeling if the goal is to represent information objects in the problem domain such that they correspond transparently ("one-to-one") to the user's conceptual model of objects in this domain. Source: http://www.oasis-open.org/cover/xmlAndSemantics.html
Why RDF? XML’s model is a tree, i.e., a strong hierarchy applications may rely on hierarchy position (e.g., li in HTML) relatively simple syntax and structure not easy to combine trees RDF’s model is a loose collections of relations applications may do “database”-like search not easy to recover hierarchy easy to combine relations in one big collection great for the integration of heterogeneous information
Ontologies RDF connects to ontologies, written in OWL, DAML+OIL or some other language, enabling machines to appear to understand what it means to say that “Jens Liegle is an employee of Georgia State University.” Ontologies An ontology is a formal, explicit specification of a shared conceptualization. Consensual Knowledge Snapshot of a Vocabulary An ontology provide a shared vocabulary, which can be used to model a domain, that is, the type of objects and/or concepts that exist, and their properties and relations Ontologies consist ofThe sky is the limit…
Academic Research
Biological Sciences: small findings from a larger number of experiments are currently being overlooked by many scientists because they have no idea what findings are out there
Alternative Opinions
There are many problems on the horizon for the Semantic Web:
Issues with personal privacy
Technology that is too complex
Specifying terms in an ontology that may be controversial
We may have simply handed off the problem: spelling corrections, abbreviations, two people with the same name
http://www.alwayson-network.com/comments.php?id=7480_0_3_0_C
http://news.com.com/Next+big+step+for+the+Web--or+a+detour/2100-1032_3-5605922.html?part=rss&tag=5606366&subj=news
The Semantic Web The Problem There is a lot of information on the web. 532,897 Terabytes of data in 2002 Approximately 40 million files How can we find what we are looking for? Current Search Engines “Which pages contain the term ______?” Solution The Semantic Web
"The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.“ [1] The Semantic Web will provide semantics for web resources Semantic Web Search Engines “What’s the temperature in Boston?” “What’s the most effective headache medicine?” “Who has the cheapest hotel in the downtown Washington DC area?” [1] Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001
RDF Today’s web is implemented by URIs, HTTP, and HTML. The Semantic Web is built with URIs, HTTP, and RDF. RDF is Resource Description Framework. If HTML can create a relationship between two items
Deficiencies of XML But I could do that with XML. XML… provides no means of validating object semantics even if these are declared informally in an XML DTD is a poor language for data modeling if the goal is to represent information objects in the problem domain such that they correspond transparently ("one-to-one") to the user's conceptual model of objects in this domain. Source: http://www.oasis-open.org/cover/xmlAndSemantics.html
Why RDF? XML’s model is a tree, i.e., a strong hierarchy applications may rely on hierarchy position (e.g., li in HTML) relatively simple syntax and structure not easy to combine trees RDF’s model is a loose collections of relations applications may do “database”-like search not easy to recover hierarchy easy to combine relations in one big collection great for the integration of heterogeneous information
Ontologies RDF connects to ontologies, written in OWL, DAML+OIL or some other language, enabling machines to appear to understand what it means to say that “Jens Liegle is an employee of Georgia State University.” Ontologies An ontology is a formal, explicit specification of a shared conceptualization. Consensual Knowledge Snapshot of a Vocabulary An ontology provide a shared vocabulary, which can be used to model a domain, that is, the type of objects and/or concepts that exist, and their properties and relations Ontologies consist of
- Classes (general things) in the many domains of interest
- The relationships that can exist among things
- The properties (or attributes) those things may have
a simple way to express and store metadata a way to “structure” and characterize the terms means to make some inference within a restricted framework
Personal Assistant Semantic Web Searches Inference Engines: take in rules and data and process them, writing out the resulting RDF triples
