The Semantic Web

Fabian Suchanek (fabian@{LASTNAME}.name)

Winter 2011

 

The purpose of this lab session is to get some hands-on experience with the Semantic Web.

Hand in the results asked for by email until Friday 9th of December 2011, 16:00.

1. Exploring the YAGO Ontology

YAGO is a large ontology that is being developed by the Max-Planck Institute for Informatics in Germany. Go to the YAGO Web site, http://yago-knowledge.org, click on the “Demo” tab and start the textual browser. This browser allows navigating through the YAGO ontology.
  1. Choose a person of public interest. Type the name in the box (with the correct captialization) and hit ENTER. If the person is in YAGO, there will be a blue link with that person's name on the right side of the screen (if it is not, try another person). Click on that link on the right hand side to show that person. As always in RDF, the person is linked to multiple other entities — to the left and to the right. Each link has a label.
  2. Find the type link (on the right hand side). This link lists the classes that the person is an instance of. Choose one class at random, click on it. Find the super-classes of that class (these are listed as subclassOf links on the right hand side). Choose one super-class. Repeat choosing one super-class until you hit the root class. Note down all classes you encounter on single one path from the person to the root, hand them in. (Note: The root class is called entity in YAGO, not resource.)
  3. Optional: Find at least one incorrect statement in the ontology. More bugs give bonus points ☺

2. Querying DBpedia with SPARQL

Try out the following:
  1. Go to the DBpedia SPARQL endpoint at http://dbpedia.org/sparql
  2. Paste the following into the query box 
    PREFIX : <http://dbpedia.org/resource/>
SELECT ?x WHERE { :Elvis_Presley rdf:type ?x . }
LIMIT 100
    This query lists all classes that Elvis Presley is an instance of. (The namespace rdf is automatically known.) Hand in a sample of the results.
  3. Can you modify the query so that it lists all facts with Elvis Presley in the position of the subject, not just the ones with the rdf:type relation? You should find facts about his names, and associated bands. Hand in the query and a sample of the results.
  4. Write a query that lists all the entities that were born on the same day as Elvis. The SPARQL query itself should not contain the birthdate of Elvis ("1935-01-08")! Use the relation <http://dbpedia.org/property/birthDate>. Hand in the query and the results.
If the interface does not work, try reloading, also with a different limit. If the query does not work, check whether you used the right syntax.

3. Microdata

Here, we are going to try out some HTML with Microdata.
  1. Make an HTML page with Microdata about yourself with at least 5 facts. Use standard identifiers from Schema.org.
  2. Use the Linter Parser to verify you page.
  3. Optional: Go beyond the simple example, add some more facts, make your address complete, etc.